IN VIVO BIODOSIMETRY OF PORCINE T-LYMPHOCYTE SUBSETS AND NK CELLS

The aim of the present study was to evaluate the biodosimetric potential of peripheral blood lymphocytes, particularly of T-cell subsets (null and T helper) and natural killer cells (NK), upon exposure to gamma irradiation (60Co) in vivo. For this purpose, the change in relative numbers of NK cells and T-lymphocyte subsets, as well as in the H2AX phosphorylation rate, were evaluated as potential early markers of the lymphocytic response to irradiation in vivo. These experiments were performed on a Large White Pig model. As a result, significant but not dose-dependent changes in the proportion of lymphocyte subpopulations (NK cells, null and T helper cells) were found after exposure to ionising radiation in vivo. On the other hand, circulating NK cells showed relatively higher radioresistance capacity when compared to the T-lymphocyte subsets; however, gamma-H2AX expression showed no significant difference between the evaluated lymphocyte subsets.

Single-Cell RNA-Sequencing Identifies Activation of TP53 and STAT1 Pathways in Human T Lymphocyte Subpopulations in Response to Ex Vivo Radiation Exposure

Detrimental health consequences from exposure to space radiation are a major concern for long-duration human exploration missions to the Moon or Mars. Cellular responses to radiation are expected to be heterogeneous for space radiation exposure, where only high-energy protons and other particles traverse a fraction of the cells. Therefore, assessing DNA damage and DNA damage response in individual cells is crucial in understanding the mechanisms by which cells respond to different particle types and energies in space. In this project, we identified a cell-specific signature for radiation response by using single-cell transcriptomics of human lymphocyte subpopulations. We investigated gene expression in individual human T lymphocytes 3 h after ex vivo exposure to 2-Gy gamma rays while using the single-cell sequencing technique (10X Genomics). In the process, RNA was isolated from ~700 irradiated and ~700 non-irradiated control cells, and then sequenced with ~50 k reads/cell. RNA in each of the cells was distinctively barcoded prior to extraction to allow for quantification for individual cells. Principal component and clustering analysis of the unique molecular identifier (UMI) counts classified the cells into three groups or sub-types, which correspond to CD4+, naïve, and CD8+/NK cells. Gene expression changes after radiation exposure were evaluated using negative binomial regression. On average, BBC3, PCNA, and other TP53 related genes that are known to respond to radiation in human T cells showed increased activation. While most of the TP53 responsive genes were upregulated in all groups of cells, the expressions of IRF1, STAT1, and BATF were only upregulated in the CD4+ and naïve groups, but were unchanged in the CD8+/NK group, which suggests that the interferon-gamma pathway does not respond to radiation in CD8+/NK cells. Thus, single-cell RNA sequencing technique was useful for simultaneously identifying the expression of a set of genes in individual cells and T lymphocyte subpopulation after gamma radiation exposure. The degree of dependence of UMI counts between pairs of upregulated genes was also evaluated to construct a similarity matrix for cluster analysis. The cluster analysis identified a group of TP53-responsive genes and a group of genes that are involved in the interferon gamma pathway, which demonstrate the potential of this method for identifying previously unknown groups of genes with similar expression patterns.

Relationship between sleep disorders and lymphocyte subsets and cytokines in patients with lung cancer

This study aimed to investigate the relationship between sleep disorders and lymphocyte subsets and cytokines in patients with lung cancer undergoing radiotherapy, and to establish a theoretical foundation for predicting sleep disorders and preventing interventions in radiotherapy in lung cancer patients. Ninety-two patients with lung cancer requiring radiotherapy were selected as the study subjects. The patients' demographic data and disease-related conditions were investigated. Their quality of sleep was measured before radiotherapy, after two and four weeks of radiotherapy, and at the end of radiotherapy. According to the Pittsburgh Sleep Quality Index Number Table (PSQI), patients with PSQI score> 7 points were put into a sleep disorder group, and patients with PSQI score 0-7 were put into a normal sleep group. Lymphocyte subsets were enumerated and cytokine levels (IL-6, IL-1b) were measured during these four periods. The difference in sleep disorders at four weeks between patients with or without synchronous chemotherapy was statistically significant (P less than 0.05). The levels of lymphocyte subsets in the sleep disorder group and the control sleep group showed no difference in the index of lymphocyte subsets before radiotherapy. In the sleep disorder group, CD4+ cells were lower after two weeks of radiotherapy (P less than 0.05). After four weeks of radiotherapy, CD3+, CD4+, and CD16+56+ subsets were lower (P less than 0.05). At the end of radiotherapy, there was no difference in each index. There was no significant difference in IL-6 levels between the two groups before radiotherapy, after two weeks, or after four weeks (P greater than 0.05). At the end of radiotherapy, IL-6 levels in the sleep disorder group were higher than those in the control sleep group (P less than 0.05). There was no significant difference in IL-1b between the two groups (P greater than 0.05). In conclusion, monitoring of T-lymphocyte subsets and IL-6 levels in patients is enhanced during radiotherapy. Clinically effective programs of radiotherapy for lung cancer improve the body's immune status.

Fractionated Radiation Therapy Stimulates Antitumor Immunity Mediated by Both Resident and Infiltrating Polyclonal T-cell Populations when Combined with PD-1 Blockade

Purpose: Radiotherapy is a highly effective anticancer treatment forming part of the standard of care for the majority of patients, but local and distal disease recurrence remains a major cause of mortality. Radiotherapy is known to enhance tumor immunogenicity; however, the contribution and mechanisms of radiotherapy-induced immune responses are unknown.Experimental Design: The impact of low-dose fractionated radiotherapy (5 × 2 Gy) alone and in combination with αPD-1 mAb on the tumor microenvironment was evaluated by flow cytometry and next-generation sequencing of the T-cell receptor (TCR) repertoire. A dual-tumor model was used, with fractionated radiotherapy delivered to a single tumor site to enable evaluation of the local and systemic response to treatment and ability to induce abscopal responses outside the radiation field.Results: We show that fractionated radiotherapy leads to T-cell infiltration at the irradiated site; however, the TCR landscape remains dominated by polyclonal expansion of preexisting T-cell clones. Adaptive resistance via the PD-1/PD-L1 pathway restricts the generation of systemic anticancer immunity following radiotherapy, which can be overcome through combination with αPD-1 mAb leading to improved local and distal tumor control. Moreover, we show that effective clearance of tumor following combination therapy is dependent on both T cells resident in the tumor at the time of radiotherapy and infiltrating T cells.Conclusions: These data provide evidence that radiotherapy can enhance T-cell trafficking to locally treated tumor sites and augment preexisting anticancer T-cell responses with the capacity to mediate regression of out-of-field tumor lesions when delivered in combination with αPD-1 mAb therapy. Clin Cancer Res; 23(18); 5514-26. ©2017 AACR.

[The Influence of UV-Light on the Sub-Populational Composition and Expression of Membrane Markers of Lymphocytes of Donor Blood]

The influence of UV-light (240-390 nm) at dozes of 151 and 755 J/m2 on the content of membrane markers of lymphocytes using the method of flow cytometry was investigated. It was demonstrated that during incubation of UV-irradiated lymphocytes the change of their populational and sub-populational composition occurs. Expression of complexes of CD3, CD 19,.CD8, CD 16, CD25 and CD95 increased. This increase was caused mainly by de novo synthesis. UV-light had immunostimulating effect on CD8+ T-lymphocyte population. Together with the increase of cytotoxic cells and NK-cells, activation of lymphocytes (increased amount of CD25+ and CD95+ cells) took place. Amount of cells undergone apoptosis or necrosis increased proportionally to the dosage. These changes were more expressed during incubation of lymphocytes in nutrition medium without autological blood serum, e.g. under deficiency of growth factors and antioxidants.

Effect of neoadjuvant chemoradiation on tumor-infiltrating/associated lymphocytes in locally advanced rectal cancers

BACKGROUND

Lymphocytes and natural killer cells (NK) appear to be important in colorectal cancer. Their role in chemoradiotherapy for rectal cancers is unclear. We evaluated T-lymphocytes (CD3), sub-groups CD4 and CD8, and NK cells (CD56+CD57) in normal and rectal tumor tissues pre- and post-chemoradiotherapy, and investigated their relationship to tumor regression grade, disease-free survival and pathological stage.

MATERIALS AND METHODS

Tissue microarrays from colonoscopic biopsies, resection specimens and normal tissues, from 52 patients, were immunostained.

RESULTS

NK cell counts were significantly lower in tumor samples compared to normal tissues (p=0.007). T-lymphocyte counts were higher in post-treatment compared to pre-treatment samples (p=0.025), specifically in the CD8 subgroup after long-course treatment. The results suggested an association between post-treatment CD8 and NK cell counts with higher tumor regression. No associations were found with regard to stage or disease-free survival.

CONCLUSION

NK cell counts were significantly reduced in rectal cancers compared to normal tissues, while total T-lymphocyte counts increased post-chemoradiotherapy. Both appeared important in tumor regression.

Immune Activation and Radioprotection by Propolis

In this study, we focused on immune stimulation by Propolis, and examined changes in the effect of irradiation after Propolis administration. We also examined the radioprotective effect of Propolis by observing its effect on the immune system. The effect of immune activation by Propolis was investigated by measuring the total immunoglobulin (Ig) G and IgM. The radioprotective effect of immune activation by Propolis was investigated by measuring the T-lymphocyte subsets in the peripheral blood of mice following whole body irradiation.

Compared with the control group, the IgG was significantly reduced in the Propolis group, indicating that Propolis suppressed IgG production. ELISA revealed that the amount of IgM in mouse serum was significantly higher in the Propolis group as compared with the control group, indicating that Propolis increased IgM production.

The number of CD4-positive cells was increased only in the Propolis group. Likewise, the number of CD4-positive cells increased by 81% in the Propolis with irradiation group compared with the irradiation group alone. Compared with the control group, the Propolis group increased CD8-positive cells. Compared with the irradiation alone group, CD8-positive cells were decreased by Propolis with irradiation group.

Propolis activated macrophages to stimulate interferon (IFN)-γ production in association with the secondary activation of T-lymphocytes, resulting in a decrease in IgG and IgM production. Cytokines released from macrophages in mouse peripheral blood after Propolis administration activated helper T-cells to proliferate. In addition, activated macrophages in association with the secondary T-lymphocyte activation increased IFN-γ production and stimulated proliferation of cytotoxic T-cells and suppressor T-cells, indicating the activation of cell-mediated immune responses.

Skin exposure to chronic but not acute UV radiation affects peripheral T-cell function

Ultraviolet (UV) radiation (UVR) produces deleterious effects that may finally lead to carcinogenesis. These adverse effects include tissue inflammation, free radical formation with consequent oxidation of proteins and lipids, DNA damage, and immune function suppression. The aim of this study was to evaluate the effects of UVR at the local and systemic levels following acute (4 consecutive days with 0.5 minimal erythema dose [MED]) or chronic (20 consecutive days with 0.25 MED) exposure. Locally, histological alterations and epidermal T-cell populations were studied. Systemically, inguinal lymph-node and spleen T cells were analyzed with respect to proliferative response and cytokine production against a nonspecific mitogen. Lymph-node T-cell populations were also characterized. Our results indicated that while both acute and chronic UVR produced epidermal hyperplasia and a decrease in epidermal T-cell density, acute UVR increased T-cell proliferative response, while chronic UVR produced the opposite effect, shifting the cytokine production toward a Th2/Treg profile. Therefore, even though acute irradiation produced a direct effect on skin, it did not correlate with a marked modification of overall T-cell response, which is in contrast to marked effects in chronically irradiated animals. These findings may contribute to understanding the clinical relevance of occupational UVR exposure, typically related to outdoor activities, which is associated with nonmelanoma skin carcinogenesis.

Immediate and short-, mid- and long-term effects of in vivo ionizing radiation exposure in BALB/c mice: I. Activation of lymphocytes and subpopulations

BACKGROUND

The main aim of this work was to study the effects of single whole-body irradiation (WBI) on the lymphoproliferative response in radiation-sensitive BALB/c mice.

MATERIALS AND METHODS

Mice were irradiated (0-5 Gy) and euthanized immediately afterward; other animals were subjected to WBI (4 Gy) and were analyzed after periods of 0-180 days. Splenic cell number, lymphoproliferative response and lymphocyte subpopulations were studied.

RESULTS

This study shows that immediately after exposure, an inhibition of the basal mitogen lymphoproliferative response was produced; furthermore, B-cells appear to be more radiosensitive than T-cells. However, up to 90 day's post-irradiation, mice spleens clearly show low cell numbers, and subpopulations and T-cell mitogens did not return to normal, while the basal response and B-cell mitogens peaked on day 15 post-WBI.

CONCLUSION

In our model, B-cells regenerate earlier than T-cells, while Th lymphocytes regenerate faster than Tc lymphocytes.

Occupational exposure to ionizing radiation has no effect on T‐ and B‐cell total counts or percentages of helper, cytotoxic and activated T‐cell subsets in the peripheral circulation of male radiation workers

PURPOSE

To investigate changes in immune cell subsets in the peripheral circulation of a male population occupationally exposed to ionizing radiation.

MATERIALS AND METHODS

Peripheral blood samples were taken from 194 male workers with cumulative exposures of >200 mSv (mean exposure 331.5 mSv, mean age 51 years) and from a reference population of 131 male workers with cumulative exposures of <27.5 mSv (mean exposure 13.9 mSv, mean age 47 years). Samples were analysed by flow cytometry for T- and B-cell total counts and for the T-cell subset percentages of CD4+ (helper T-cells), CD8+ (cytotoxic T-cells) and CD3+/HLA-DR+ (activated T-cells).

RESULTS

Comparison of the >200 and <27.5 mSv exposure groups using linear regression analysis showed no statistically significant differences between the two groups for T-cell total count, B-cell total count or for percentages of the T-cell subsets CD4+, CD8+ or CD3+/HLA-DR+ and CD4+:CD8+. However, statistically significant increases in both T- and B-cell total counts were observed within the two exposure groups and data pooled from both groups when non-smokers (never and ex-smokers) were compared with current smokers. For pooled data T-cell total count increased in smokers by 35% (p=0.0001) and B-cell total count increased by 37% (p=0.0004).

CONCLUSIONS

No significant immunological effects were observed in male radiation workers with cumulative exposures of >200 mSv when compared with a reference population with cumulative exposures of <27.5 mSv, although highly significant increases in both T- and B-cell total counts were observed in smokers compared with non-smokers.

Differential responses of cellular immunity in patients undergoing neoadjuvant therapy followed by surgery for carcinoma of the oesophagus

BACKGROUND

To compare immune responses following neoadjuvant chemoradiation therapy in combination with hyperthermia plus surgery to those induced by surgery alone in patients with oesophageal cancer.

METHODS

Thirty-two patients with histopathologically proven oesophageal cancer, scheduled for potentially curative transhiatal or transthoracic oesophagectomy with (neo, n = 20) or without (control, n = 12) neoadjuvant thermochemoradiation therapy (ThCR) were included. Peripheral blood samples were obtained before ThCR, after 2 weeks of ThCR, 1 day before surgery, on postoperative days 1, 3, 7, and 6 weeks after surgery, for white blood cell counts, lymphocyte subsets and T helper type 1 (Th1) and type 2 (Th2) lymphocyte responses.

RESULTS

Neo patients showed a significant decrease in granulocytes and lymphocyte subsets, and T cell cytokines after 2 weeks of ThCR. Only CD8+ (cytotoxic) T cells recovered after ThCR to reach normal levels prior to surgery. In contrast, CD4+ T (helper) cells, and NK- and B cells in neo patients did not recover prior to surgery (all P < 0.05). Oesophagectomy induced a significant increase in granulocytes and a decrease in lymphocytes (and subsets). Only those subsets that had not recovered after ThCR (CD4+ T cells, NK and B cells but not CD8+ T cells), were significantly lower (all P < 0.05) during the entire postoperative study period. Postoperatively, the stimulated cytokine production capacity of Th1 and Th2 cells, corrected for number of T cells, was not significantly different between the groups.

CONCLUSION

Neoadjuvant thermochemoradiation for oesophageal cancer caused significant disturbances of host cellular immunity with reduced T, NK and B cell counts, and differential recovery of cytotoxic and helper T cells leading to prolonged T cell imbalance that extends beyond the time of surgery. The functional and anti-tumour consequences of this immunodisturbance need further investigation, as recovery of T helper cytokine production towards surgery was less impaired than T helper cell counts.

Whole-body irradiation and long-term modification of bone marrow-derived cell populations by low- and high-LET radiation

BACKGROUND

The major aim of this study was to quantify long-term changes in bone marrow-derived cell populations after exposure to radiations of differing quality.

MATERIALS AND METHODS

Mice were whole-body irradiated to 2 Gy gamma, proton, carbon or iron radiation, and euthanized approximately 110 days later for immunocyte phenotyping.

RESULTS

Splenic lymphocytes and mono/macrophages increased after gamma-rays when compared to 0 Gy and one or more of the other groups. There were high T cells (carbon vs. 0 Gy), high B cells (gamma-rays vs. 0 Gy), and low natural killer (NK) cells (proton and carbon vs. 0 Gy). All radiations, except gamma-rays, increased CD62L+ memory T cell counts, whereas CD62L+ B cells increased only after gamma-rays.

CONCLUSION

There were significant aberrations in many immune parameters nearly 4 months after exposure to various forms of radiation. This suggests radiation exposure can have long-term health consequences.

Tolerance to proinsulin-2 is due to radioresistant thymic cells

Proinsulin is a key Ag in type 1 diabetes, but the mechanisms regulating proinsulin immune tolerance are unknown. We have shown that preproinsulin-2 gene-deficient mice (proins-2(-/-)) are intolerant to proinsulin-2. In this study, we analyzed the mechanisms underlying T cell-mediated tolerance to proinsulin-2 in 129/Sv nonautoimmune mice. The expression of one proinsulin-2 allele, whatever its parental origin, was sufficient to maintain tolerance. The site of proinsulin-2 expression relevant to tolerance was evaluated in thymus and bone marrow chimeras. CD4+ T cell reactivity to proinsulin-2 was independent of proinsulin-2 expression in radiation-sensitive bone marrow-derived cells. A wt thymus restored tolerance in proins-2(-/-) mice. Conversely, the absence of the preproinsulin-2 gene in radioresistant thymic cells was sufficient to break tolerance. Although chimeric animals had proinsulin-2-reactive CD4+ T cells in their peripheral repertoire, they displayed no insulitis or insulin Abs, suggesting additional protective mechanisms. In a model involving transfer to immunodeficient (CD3epsilon(-/-)) mice, naive and proinsulin-2-primed CD4+ T cells were not activated, but could be activated by immunization regardless of whether the recipient mice expressed proinsulin-2. Furthermore, we could not identify a role for putative specific T cells regulating proinsulin-2-reactive CD4+ T in transfer experiments. Thus, proinsulin-2 gene expression by radioresistant thymic epithelial cells is involved in the induction of self-tolerance, and additional factors are required to induce islet abnormalities.

A placebo-controlled randomized study on the clinical effectiveness, immunohistochemical changes and protoporphyrin IX accumulation in fractionated 5-aminolaevulinic acid-photodynamic therapy in patients with psoriasis

BACKGROUND

Topical 5-aminolaevulinic acid (ALA)-photodynamic therapy (PDT) for the treatment of psoriasis has been evaluated in a few studies. In these studies different treatment parameters were used, there was a variable clinical response, and a nonhomogeneous fluorescence was seen after irradiation with Wood's light.

OBJECTIVES

To study the clinical effectiveness, immunohistochemical changes and protoporphyrin IX accumulation in ALA-PDT in patients with psoriasis. Eight patients with stable plaque psoriasis with symmetrical involvement were included in the study. Two symmetrical plaques were randomly allocated to PDT either with 10% ALA or with placebo. Irradiation consisted of 2 and 8 J cm(-2) with a dark interval of 2 h (Waldmann PDT 1200 L, 600-750 nm, 40 mW cm(-2)) once weekly for 4 weeks. Before, during and after irradiation, fluorescence diagnosis was performed. Biopsies were taken at baseline, week 1 and week 6 for immunohistochemical assessment. Psoriatic plaques were clinically assessed using the plaque severity (sum) score. Fluorescence diagnosis was performed and expression of immunohistochemical markers for proliferation, differentiation and T-cell infiltration [Ki67, keratin 10 (K10), CD4, CD8 and CD45RO] was assessed.

RESULTS

From week 1 up to week 6, ALA-PDT gave a significant reduction in the number of Ki67+ nuclei, while the K10 expression increased. After 6 weeks significant improvement was observed for CD8 and CD45RO. These changes were absent in the placebo-treated lesions. The sum scores were also significantly lower in the ALA-treated plaques. Heterogeneity of macroscopic fluorescence was observed during treatment despite keratolytic treatment.

CONCLUSIONS

The present study shows that clinical improvement during fractionated ALA-PDT in psoriasis parallels histological improvement as seen in normalization of epidermal proliferation, differentiation and infiltration of relevant T-cell subsets. Optimizing the current treatment protocol may increase clinical efficacy further.

Stem Cell Transplantation with S-59 Photochemically Treated T-Cell Add-Backs to Establish Allochimerism in Murine Thalassemia

Hematopoietic cell transplantation (HCT) from HLA-identical sibling donors has curative potential for beta-thalassemia. The probability of surviving free of thalassemia under these conditions is approximately 85%. The application of this therapy is limited because many patients lack an HLA-identical sibling donor. HLA-mismatched stem cell transplantation for thalassemia is severely restricted by graft rejection and the risks for graft-versus-host disease (GVHD). Thus, the development of a novel method that facilitates immunological tolerance and improves the safety of HLA-mismatched HCT would greatly expand the opportunity of HCT for thalassemia patients. We hypothesized that removal of T cells from the donor hematopoietic stem cell preparation and subsequent add-back after photochemical treatment with S-59, a psoralen, would promote and stabilize the engraftment and significantly reduce the risk of GVHD. This was tested in a MHC-mismatched HCT model of murine thalassemia. S-59-treated T cells were infused simultaneously with bone marrow-derived stem cells into mice with a heterozygous deletion of one beta-globin alleles that had been conditioned with a sublethal dose of total body irradiation. Mice that received treated T cells showed increased engraftment compared to those that did not receive T cells. T-cell treatment improved survival without GVHD compared to recipients that received untreated T cells. We conclude that photochemical treatment of T cells facilitates engraftment and minimizes GVHD in allo-HCT for murine thalassemia, and sets the stage for further development of such protocols for the treatment of patients with thalassemia.

Transcriptional response to ionizing radiation in lymphocyte subsets

Human lymphocyte subpopulations differ in their cellular responses to ionizing radiation. To shed light on the molecular basis of this effect, we characterized the transcriptional response to 1 Gy X-rays of CD4+ T lymphocytes. Of 18,433 genes tested, 102 were modulated more than 1.5-fold. The majority of the strongly activated genes were p53 targets involved in DNA repair and apoptosis. The expression of three of these genes was further tested by quantitative RT-PCR in lymphocyte subpopulations [CD4+ and CD8+ T, CD19+ B, CD56+ natural killer cells and peripheral blood lymphocytes (PBLs)] from ten adult donors. In contrast to DDB2, TNFRSF10B and BAX were differentially modulated among the subpopulations and the PBLs, being more activated in irradiated CD19+ B and CD8+ T lymphocytes. The level of BAX activation in the various subpopulations correlated with the sensitivity of the cells to radiation, suggesting its possible role in the differential radiosensitivity of hematopoietic cell subsets.

Regulatory T Cells Induced by Ultraviolet Radiation

Regulatory T cells belong to a subset of T lymphocytes which suppress immune reactions in an antigen-specific fashion. They play an important role in the prevention of autoimmune diseases. Ultraviolet (UV) radiation was also found to suppress the immune system in an antigen-specific fashion mediated by UV-induced regulatory T cells. Induction of these cells by UV radiation is an active process which requires antigen presentation by UV-damaged but still viable Langerhans cells in the lymph nodes. UV-induced regulatory T cells have been recently characterized to express CD4 and CD25 and to release the immunosuppressive cytokine interleukin-10 upon activation. Once activated in an antigen-specific fashion, they suppress immune responses in a general fashion via the release of interleukin-10, a phenomenon called bystander suppression. Upon intravenous injection, UV-induced regulatory T cells primarily migrate into the lymph nodes, explaining why they preferentially suppress sensitization. Recently, the development of regulatory T cells was demonstrated in an experimental model of photopheresis, a therapeutic regimen which is used for the therapy of autoimmune diseases, transplant rejection and graft-versus-host disease. Further characterization of these cells will determine whether they can be applied therapeutically in the future with the ultimate aim to induce specific immunosuppression.

Several Genes Contribute to the Production of Autoreactive B and T Cells in the Murine Lupus Susceptibility Locus Sle1c

The systemic lupus erythematosus 1 (Sle1) locus mediates the loss of tolerance to nuclear Ags in the NZM2410 mouse model of lupus through intrinsic defects in both B and T cells. Congenic analysis has shown that Sle1 corresponds to at least three genetic loci, Sle1a, Sle1b, and Sle1c. Telomeric Sle1c is associated with abnormal B cell responses to subthreshold stimulation with anti-IgM and C3d and with decreased T-dependent humoral immune responses. We have proposed that these phenotypes resulted from polymorphisms in the C3 complement receptor Cr2 gene. We have also found that Sle1c was associated with the production of histone-specific autoreactive CD4(+) T cells, which correlated with higher activation and proliferative responses, and a reduction in the CD4(+)CD25(+)CD62L(+)forkhead/winged helix transcription factor gene (Foxp3(+)) compartment. In this study we showed, using congenic recombinants, that the decreased humoral immune response and impaired GC formation map to the NZM2410 Cr2 allele. A chronic graft-vs-host disease model also showed that Sle1c produces significantly more autoreactive B cells than B6 controls, and that this phenotype maps to two regions excluding the Cr2 gene. Mixed bone marrow chimera demonstrated that the increased activation, proliferative response, and reduced regulatory T cell compartment were intrinsic to Sle1c-expressing CD4(+) T cells. These phenotypes mapped to the same two loci identified with the chronic graft-vs-host disease model, excluding the Cr2 region. Overall, these results show that Sle1c results in the production of autoreactive B and T cells through the expression of three different genes, one of which is consistent with Cr2, based on the phenotypes of the Cr2-deficient mice, and the other two corresponding to as yet unidentified genes.

Ultraviolet-A1 phototherapy modulates Th1/Th2 and Tc1/Tc2 balance in patients with systemic lupus erythematosus

OBJECTIVE

Ultraviolet-A1 (UVA1) phototherapy is effective for a variety of dermatological diseases. We examined the effectiveness and reliability of low-dose UVA1 phototherapy (60 kJ/m2/treatment) in patients suffering from systemic lupus erythematosus (SLE). We studied the changes in immunological parameters.

METHODS

The patients received a 9-week course of phototherapy according to the following regimen: five times a week during the first 3 weeks, three times a week during the second 3 weeks and twice during the last 3 weeks. Among other things, we analysed the proportions of T helper 1 (Th1), Th2, T cytotoxic (Tc1) and Tc2 cell populations in the peripheral blood of patients by flow cytometric detection of intracytoplasmic interferon gamma (IFN-gamma) and interleukin 4 (IL-4).

RESULTS

Our study showed the improvement of clinical symptoms determined by the subjective clinical disease activity scoring and the SLE Disease Activity Index (SLEDAI). By the end of UVA1 phototherapy, the mean value of SLEDAI had decreased from 7.2+/-5.6 to 0.9+/-1.8, which was significant (P = 0.005). Immunological investigations detected a decrease in the frequency of IFN-gamma-producing Th1 and Tc1 cells and a decrease in the Th1/Th2 and Tc1/Tc2 ratios after UVA1 therapy.

CONCLUSION

According to the literature, IFN-gamma has a pathogenic role in the development of SLE. We observed a decreased proportion of IFN-gamma-secreting cells, which we think is presumably one of the beneficial effects of UVA1 therapy. On the basis of our study, UVA1 phototherapy does seem to be an effective adjuvant in the treatment of SLE patients.

[Effect of low intensity and very high frequency electromagnetic radiation on occupationally exposed personnel]

OBJECTIVE

To investigate the effect of low intensity and very high frequency (VHF) electromagnetic radiation (170 MHz) on nervous system function and serum enzymes and immune function in human subjects with occupational exposure to VHF.

METHODS

To measure the intensity of VHF and other environmental factors on the spot, to hold the questionnaire about chief complaints, to examine the rheoencephalography and the neurobehavior function, to analyze ALT, AST, ALP and LDH, and IgA, IgM and IgG in experimental group and control group.

RESULTS

The intensity of VHF (direction of antenna: 0 degrees, 10 m and 135 degrees, 20 m) was higher than that of national standard on-the-spot. The incidences of symptoms such as headache, insomnia and amnesia etc. was significantly higher in experimental group (P < 0.01). Rheoencephalography indicated that the raising time of both left [(0.155 3 +/- 0.057 9) s] and right [(0.154 1 +/- 0.059 2) s] in the experimental group after exposure were significantly longer than before exposure [(0.104 4 +/- 0.030 2) s, (0.103 2 +/- 0.030 4) s respectively] or in the control [(0.118 5 +/- 0.056 8) s, (0.117 7 +/- 0.057 5) s respectively, (P < 0.01)]. Neurobehavior function test showed that digital symbol, digital span and pursuit aiming test were decreased after exposure in the experimental group (P < 0.01). Serum enzyme analysis showed that AST, ALP and LDH were significantly increased after exposure in the experimental group (P < 0.01). No marked change was found in IgA level, while the levels of IgM and IgG after exposure in the experimental group especially the latter were significantly increased (P < 0.01).

CONCLUSIONS

Low-intensity VHF radiation can decrease the nervous system function in occupationally exposed personnel and induce increase in some kinds of enzymes and immunoglobulins.

Diminished cellular and humoral immunity in workers occupationally exposed to low levels of ionizing radiation

BACKGROUND

It has been reported that subgroups of T-lymphocytes are affected at different levels and different cell groups of immune system give different responses in individuals exposed to long-term ionizing radiation. The aim of this study was to investigate the effect of occupational exposure to low levels of ionizing radiation in selected indices of cellular and humoral immunity in radiology workers.

METHODS

Level of subgroups of peripheral blood lymphocytes, complements (C(3), C(4)), and total immunoglobulins (IgG, IgA, IgM) were analyzed in 50 radiology workers occupationally exposed to low levels of ionizing radiation and 35 age-matched healthy controls.

RESULTS

CD4(+) T lymphocyte (T-helper) levels were determined as significantly low in radiology workers exposed to ionizing radiation compared with controls (p <0.05). There were no statistically significant differences in groups in terms of other subgroups of lymphocytes (p >0.05). In addition, levels of serum total IgG, IgA, IgM, C(3,) and C(4) were determined as significantly lower in workers exposed to ionizing radiation compared with controls (p <0.001). Total IgA and IgM levels in radiology workers who were smokers were determined as significantly lower compared with non-smoking radiology workers (p >0.05).

CONCLUSIONS

Levels of CD4(+) T lymphocytes and humoral immune response (total immunoglobulins and complements) were determined as weaker in workers exposed to low levels of ionizing radiation compared with controls, indicating the importance of taking appropriate measures to protect radiology workers from exposure to ionizing radiation and for these workers to avoid smoking. Further studies are needed for determining the appropriateness of periodic check-ups of immune functions and the most efficient and cost-effective ways of monitoring immune functions in radiology workers for detecting early changes in the immune system.

Host conditioning is a primary determinant in modulating the effect of IL-7 on murine graft-versus-host disease

Interleukin-7 has been shown to enhance T cell reconstitution after allogeneic bone marrow transplantation, in part, by expansion of mature donor T cells, but whether IL-7 also exacerbates graft-vs-host disease (GVHD) remains unresolved. To address this issue, we examined the effect of IL-7 on GVHD induction using a well-defined murine GVHD model (B6-->B6AF1/J). Administration of IL-7 to nonirradiated B6AF1/J recipients of B6 T cells resulted in expansion of splenic donor CD4(+) and CD8(+) T cells and increased GVHD mortality. In contrast, administration of IL-7 on the same schedule failed to increase GVHD mortality in either sublethally or lethally irradiated animals that received graded doses of T cells designed to induce varying degrees of GVHD severity. Moreover, IL-7 failed to increase the number of alloreactive T cells when examined in a murine model (B6-->BALB.B) that allowed for direct quantitation of graft-vs-host-reactive T cells. The combination of irradiation and transplantation of alloreactive donor T cells resulted in significantly increased levels of endogenous splenic IL-7 mRNA when compared with nonirradiated transplanted animals, providing a potential explanation for why exogenous IL-7 did not increase GVHD severity in these mice. We conclude that host conditioning modulates the ability of exogenous IL-7 to exacerbate GVHD and that this occurs through induction of endogenous IL-7 production.

Ultraviolet radiation-induced regulatory T cells not only inhibit the induction but can suppress the effector phase of contact hypersensitivity

Epicutaneous application of haptens to UV-exposed skin induces hapten-specific tolerance. This is mediated via regulatory T cells (Tr), as i.v. injection of T cells from UV-tolerized mice into naive animals renders the recipients unresponsive to the respective hapten. However, when UV-induced Tr are injected i.v. into sensitized mice, contact hypersensitivity (CHS) is not suppressed, suggesting that Tr inhibit the induction, but not the elicitation, of CHS and are inferior to T effector cells. As sensitization takes place in the lymph nodes, but elicitation occurs in the area of challenge, we postulated that Tr injected i.v. locate to the lymph nodes and not to the periphery and therefore only suppress the induction, not the elicitation, of CHS. Indeed, i.v. injection of Tr into sensitized mice did not inhibit CHS, although injection of Tr into the ears of sensitized mice suppressed the challenge. Inhibition was hapten specific, as injection of dinitrofluorobenzene (DNFB)-specific Tr into the ears of oxazolone (OXA)-sensitized mice did not affect challenge with OXA. However, when ears of OXA-sensitized mice were injected with DNFB-specific Tr and painted with DNFB before OXA challenge, CHS was suppressed. Inhibition correlated with the local expression of IL-10. Depletion studies and FACS analysis revealed that Tr express the lymph node-homing receptor L-selectin, but not the ligands for the skin-homing receptors E- and P-selectin, suggesting that UV-induced Tr, although able to inhibit T effector cells, do not suppress the elicitation of CHS upon i.v. injection, because they obviously do not migrate into the skin.

Elevated interleukin-9 receptor expression and response to interleukins-9 and -7 in thymocytes during radiation-induced T-cell lymphomagenesis in B6C3F1 mice

Dysregulation of cytokine receptor expression and responsiveness to cytokines is hypothesized to play an important role in the development and expansion of preneoplastic cells or progression of neoplastic cells during the early and late stages of leukemogenesis. To determine the crucial changes in initiated cells that confer significant growth during the early stage of radiation-induced lymphomagenesis, we examined both the expression of receptors for thymus-derived cytokines and thymocyte response to cytokines before the onset of T cell lymphomas in B6C3F1 mice after split-dose irradiation. After irradiation, thymic T cell subsets underwent delayed regeneration consisting of two phases as determined by receptor expression. The first phase occurred within 1 week post-irradiation and was accompanied by transient expansion of T cell subsets strongly expressing receptor genes for IL-1, IL-2, IL-6, IL-7, IL-15, and TNF alpha. The second phase occurred 12 weeks after irradiation and was characterized by increased expression of IL-9R alpha. Thymocytes from non-irradiated control mice were unresponsive to IL-9. However, IL-9 acted synergistically with IL-7 and PHA to stimulate the proliferation of irradiated cells during the second post-irradiation phase. Moreover, these cells showed hyper-responsiveness to IL-7 or PHA alone compared to age-matched non-irradiated control thymocytes. These results suggest that the unusual expression of IL-9 receptors and/or increased responsiveness of thymocytes to cytokines are key processes in the development of radiation-induced T cell lymphomas.

Long-lasting changes in the T-cell receptor V beta repertoires of CD4 memory T-cell populations in the peripheral blood of radiation-exposed people

To study the long-term effects of radiation-induced T-cell depletion on the T-cell receptor (TCR) Vbeta repertoires of human peripheral CD4 T-cell populations, we measured the percentages of CD4 T cells representing each of the full range of possible TCR Vbeta families in a cohort of atomic bomb survivors. We then estimated the extent to which the expression levels for individual TCR Vbeta families differed from the average expression level for that particular TCR Vbeta family across the entire cohort. We found no evidence of a systematic change in the TCR Vbeta repertoires of the naïve CD4 T-cell populations, but memory CD4 T-cell TCR Vbeta family expression levels diverged significantly from the population average for counterpart families, especially in individuals who had been exposed to higher doses and were at least 20 years of age at the time of the bombing. Comparisons of the TCR Vbeta family expression profiles in the naïve and memory CD4 T-cell pools of the same group of adult survivors revealed that differences in the TCR Vbeta repertoires of these two types of CD4 T-cell pool were larger in more heavily exposed survivors than in unexposed controls. These findings suggest that the memory CD4 T-cell pools of individuals who received significant radiation doses in adulthood may well have become (and could still be) dependent upon a much less diverse complement of TCR Vbeta families than would otherwise have been the case.

[Indices of humoral and cellular immunity in patients with chronic maxillary sinusitis after the Chernobyl accident]

An evaluation was done of immunological parameters in the post accident period in 41 examined person. Of these, 26 subjects had chronic maxillary sinusitis, 15 were healthy persons (control group). In patients with chronic maxillary sinusitis, the state of the T-system of immunity has been shown to be characterised by a drop in the total count of T-lymphocytes, T-helpers, T-suppresors. Parameters for humoral immunity are characterised by elevation of the peripheral blood levels of B-lymphocytes, prominent disimmunoglobulinaemia--significant reduction of class G immunoglobulins and macroglobulins. The T-cells-helpers ratio is significantly reduced both in group I and group II. Reduction has been ascertained in the ratio of those T-cells-suppressors blocking antibody formation by B-lymphocytes. In patients after the Chernobyl accident, there was noted a significant decline in the functional activity of macrophages.

Long-term immune dysfunction after radiotherapy to the head and neck area

BACKGROUND

Hematological side effects are not generally expected due to radiotherapy involving limited radiation fields; however, patients with squamous cell carcinoma of the head and neck (SCCH and N) receiving radiation therapy frequently have chronic intraoral infections. Xerostomia has been implicated as a cause of it, but local or systemic immune alterations are not usually considered.

METHODS

With the purpose of evaluating the impact of radiotherapy treatment to different anatomic sites on immune function, 70 patients were evaluated during and after radiotherapy: 50 cases with SCCH and N, 10 with squamous cell carcinoma of the uterine cervix (SCCUC) and 10 patients with central nervous system tumors (CNS). We analyzed lymphocyte counts and T-cell subsets, and over time, their association with the presence of intracellular infections and disease-free survival.

RESULTS

Severe lymphopenia was observed in patients with SCCUC and SCCH and N by the fifth week of treatment. Patients with CNS tumors developed mild lymphopenia. In patients with SCCH and N and UC, lower counts were seen in B cells and total T lymphocyte counts including both CD4(+) and CD8(+) cell subsets. The patients with SCCUC recovered lymphocyte counts by the 24th month but T-cell subsets lagged behind. None of the SCCH and N patients had fully recovered by 60 months of follow-up. Recurrence correlates with low lymphocyte counts.

DISCUSSION

This work highlights the vulnerability of the head and neck area to the impact of radiotherapy as a reservoir of lymphoid cells. The possibility of recovery as a consequence of thymopoiesis and/or peripheral clonal expansion may limit the antigen-specific recognition of relevant tumor or microbial antigens and cause significant and prolonged immune alterations that may impact long-term survival.

Attrition of virus-specific memory CD8+ T cells during reconstitution of lymphopenic environments

Viruses can cause a severe lymphopenia early in infection and a subsequent, lasting loss of pre-existing CD8(+) memory T cells. We therefore questioned how well virus Ag-specific memory CD8(+) T cells could reconstitute mice rendered lymphopenic as a consequence of genetics, irradiation, or viral or poly(I:C)-induced cytokines. In each case, reconstitution of the CD8(+) compartment was associated with limited division of virus-specific memory T cells and a reduction in their proportion. This indicates that foreign Ag-experienced CD44(high)CD8(+) memory T cells may respond differently to homeostatic signals than other CD44(high)CD8(+) cells, and that events inducing lymphopenia may lead to a permanent reduction in T cell memory.

Active suppression of allogeneic proliferative responses by dendritic cells after induction of long-term allograft survival by CTLA4Ig

Costimulatory blockade using cytotoxic T lymphocyte-associated antigen 4 immunoglobulin (CTLA4Ig) efficiently down-regulates immune responses in animal models and is currently used in autoimmune and transplantation clinical trials, but the precise cellular and molecular mechanisms involved remain unclear. Rats that received allogeneic heart transplants and were treated with adenoviruses coding for CTLA4Ig show long-term allograft survival. The immune mechanisms regulating induction of long-term allograft acceptance were analyzed in splenocytes using mixed leukocyte reactions (MLRs). MLRs of splenocytes but not purified T cells from CTLA4Ig-treated rats showed higher than 75% inhibition compared with controls. Splenocytes from CTLA4Ig-treated rats inhibited proliferation of naive and allogeneically primed splenocytes or T cells. MLR suppression was dependent on soluble secreted product(s). Production of soluble inhibitory product(s) was triggered by a donor antigen-specific stimulation and inhibited proliferation in an antigen-nonspecific manner. CTLA4Ig levels in the culture supernatant were undetectable and neither interleukin-10 (IL-10), transforming growth factor beta 1 (TGF beta 1), IL-4, nor IL-13 were responsible for suppression of MLRs. Inhibition of nitric oxide (NO) production or addition of IL-2 could not restore proliferation independently, but the combined treatment synergistically induced proliferation comparable with controls. Stimulation of APCs using tumor necrosis factor (TNF)-related activation-induced cytokine (TRANCE) or CD40L and addition of IL-2 normalized MLRs of CTLA4Ig-treated splenocytes. Finally, dendritic cells (DCs), but not T cells, from CTLA4Ig-treated rats inhibited naive MLRs. Altogether, these results provide evidence that after in vivo CTLA4Ig treatment, splenocytes, and in particular DCs, can inhibit alloantigen-induced proliferative responses through secretion of inhibitory products, thus promoting alloantigen-specific tolerance in vivo.

Cutting edge: homeostatic proliferation of peripheral T lymphocytes is regulated by clonal competition

Homeostatic proliferation functions to maintain peripheral T cell numbers and is regulated by cytokines. In this study, we provide evidence that T cell homeostasis is also regulated by clonal competition. Naive polyclonal T cells divided when transferred to TCR transgenic hosts, as did monoclonal T cells when transferred to TCR transgenic hosts of differing clonotype. However, T cells did not divide in hosts of identical clono-type. Transgenic T cell proliferation was inhibited in irradiated hosts of the same clonotype, while cotransferred nontransgenic T cells proliferated extensively. These results show that clonal competition is a component of homeostasis that may contribute to selection of the peripheral T cell repertoire.

Immune tolerance to combined organ and bone marrow transplants after fractionated lymphoid irradiation involves regulatory NK T cells and clonal deletion

Immune tolerance to organ transplants has been reported in laboratory animals and in humans after nonmyeloablative conditioning of the host and infusion of donor bone marrow cells. We examined the mechanisms of immune tolerance to mouse cardiac allografts in MHC-mismatched hosts that developed mixed chimerism after posttransplant conditioning with a 2-wk course of multiple doses of lymphoid tissue irradiation, depletive anti-T cell Abs, and an infusion of donor bone marrow cells. When CD1(-/-) or J(alpha)281(-/-) hosts with markedly reduced NK T cells were used instead of wild-type hosts, then the conditioning regimen failed to induce tolerance to the heart allografts despite the development of mixed chimerism. Tolerance could be restored to the CD1(-/-) hosts by infusing enriched T cells from the bone marrow of wild-type mice containing CD1-reactive T cells but not from CD1(-/-) host-type mice. Tolerance could not be induced in either IL-4(-/-) or IL-10(-/-) hosts given the regimen despite the development of chimerism and clonal deletion of host T cells to donor MHC-Ags in the IL-10(-/-) hosts. We conclude that immune tolerance to bone marrow transplants involves clonal deletion, and tolerance to heart allografts in this model also involves regulatory CD1-reactive NK T cells.

The balance between donor T cell anergy and suppression versus lethal graft-versus-host disease is determined by host conditioning

Graft-vs-host disease (GVHD) remains the most life-threatening complication following the transfer of allogeneic bone marrow into immunocompromised hosts. Transferred alloreactive T cells respond in a complex manner. While massive T cell expansion is observed upon entry into an allogeneic environment, anergy, apoptosis, and repertoire selection are also observed. The study presented here shows that alloreactive T cell expansion and differentiation vs anergy and suppression are dramatically influenced by host conditioning. Using alloreactive CD4(+) and CD8(+) TCR transgenic (Tg) T cells, a novel GVHD model is presented that allows for the visualization of how alloreactive T cells behave when host conditioning is manipulated. Following the transfer of alloreactive CD4(+) and CD8(+) TCR Tg T cells into sublethally irradiated hosts, both Tg T cells populations expand, develop effector function, and cause GVHD. In contrast, when Tg T cells are transferred in non-irradiated hosts, expansion is observed, but there is no development of effector function or disease. Assessment of CD4(+) Tg T cell function following transfer into non-irradiated hosts reveals that these CD4(+) Tg cells are profoundly anergic and have acquired a regulatory function, as manifested in their ability to suppress the expansion of naive TCR Tg T cells in vitro and in vivo as well as the development of GVHD. These findings underscore the decisive effect of the inflammatory environment created by irradiation in determining the ultimate fate and function of alloreactive T cells in vivo

Differential Sensitivity of Naive and Memory CD8+T Cells to Apoptosis in Vivo

Apoptosis is a critical regulator of homeostasis in the immune system. In this study we demonstrate that memory CD8(+) T cells are more resistant to apoptosis than naive cells. After whole body irradiation of mice, both naive and memory CD8(+) T cells decreased in number, but the reduction in the number of naive cells was 8-fold greater than that in memory CD8(+) T cells. In addition to examining radiation-induced apoptosis, we analyzed the expansion and contraction of naive and memory CD8(+) T cells in vivo following exposure to Ag. We found that memory CD8(+) T cells not only responded more quickly than naive cells after viral infection, but that secondary effector cells generated from memory cells underwent much less contraction compared with primary effectors generated from naive cells (3- to 5-fold vs 10- to 20-fold decrease). Increased numbers of secondary memory cells were observed in both lymphoid and non-lymphoid tissues. When naive and memory cells were transferred into the same animal, secondary effectors underwent less contraction than primary effector cells. These experiments analyzing apoptosis of primary and secondary effectors in the same animal show unequivocally that decreased downsizing of the secondary response reflects an intrinsic property of the memory T cells and is not simply due to environmental effects. These findings have implications for designing prime/boost vaccine strategies and also for optimizing immunotherapeutic regimens for treatment of chronic infections.

UVB-irradiated dendritic cells induce nonproliferating, regulatory type T cells

It is well established that low-dose UVB radiation inhibits the antigen-presenting cell (APC) function of murine Langerhans cells in vivo and converts them from immunogenic to tolerogenic APC. Recently, we have shown that UVB-irradiated murine bone marrow-derived dendritic cells (UVB-DC) suppressed proliferation of naive and primed T cells, but tolerized primed T cells only. To examine the underlying mechanism for these differences, naive OVA(323-339)-peptide-specific, TCR-transgenic T cells from DO11.10 mice were analyzed following coculture with unirradiated DC or UVB-DC. First, we found that UVB-DC inhibit OVA-specific T cell proliferation UVB dose and antigen dose dependently. Analysis of T cells cocultured with both, unirradiated and UVB-DC, revealed an activated T cell phenotype with increased expression of CD25 and CD69 by FACS. Supernatants harvested from cocultures with UVB-DC showed reduced levels of IFN-gamma, IL-2 and IL-4, but not TGF-beta, compared with unirradiated DC as determined by ELISA. Furthermore, these T cells did not proliferate upon restimulation. Interestingly, addition of these nonproliferating T cells to cocultures of naive T cells and freshly prepared unirradiated DC inhibited T cell proliferation depending on the number of added nonproliferating T cells. Also, in supernatants, increased levels of TGF-beta were found. Therefore, our data indicate that UVB-DC propagate T cells with a regulatory function. Since regulatory T cells are characterized by enhanced TGF-beta secretion and increased CTLA-4 expression, we currently investigate the role of CTLA-4 phenotypically and functionally. In conclusion, we have shown that UVB-DC inhibit proliferation of naive OVA-specific T cells. These T cells, exhibiting an activated phenotype and increased TGF-beta production, suppress proliferation of naive T cells cocultured with unirradiated DC. These results suggest that UVB-DC induce nonproliferating, regulatory type T cells.

P-glycoprotein targeting: a unique strategy to selectively eliminate immunoreactive T cells

T lymphocytes have been found to harbor P-glycoprotein (Pgp) and to demonstrate modulation of its ion channel transporter function according to the state of activation of T lymphocytes. We hypothesized that cytotoxic chemicals that are extruded by Pgp could be used to specifically eliminate immunoreactive T-cell populations. In this study, we evaluated the capacity of 4,5-dibromorhodamine methyl ester (TH9402), a photosensitizer structurally similar to rhodamine, a dye transported by Pgp, and which becomes highly cytotoxic on activation with visible light to selectively deplete alloreactive T lymphocytes. Stimulation of T cells with mitogens or allogeneic major histocompatibility complex-mismatched cells resulted in the preferential retention of the TH9402 rhodamine-derivative in activated T cells, both CD4+ and CD8+. Photodynamic cell therapy of TH9402-exposed T cells led to the selective elimination of immunoreactive T-cell populations. In addition, this treatment preserved resting T cells and their capacity to respond to third-party cells. Inhibition of Pgp enhanced cellular trapping of the dye in nonactivated T cells and resulted in their depletion after exposure to light. Targeting of Pgp-deficient cells may therefore represent an appealing strategy for the prevention and treatment of graft-versus-host disease and other alloimmune or autoimmune disorders.

Conversion of naive T cells to a memory-like phenotype in lymphopenic hosts is not related to a homeostatic mechanism that fills the peripheral naive T cell pool

To examine directly whether a limited number of naive T cells transferred to lymphopenic hosts can truly fill the peripheral naive T cell pool, we compared the expansion and phenotype of naive T cells transferred to three different hosts, namely recombination-activating gene-deficient mice, CD3epsilon-deficient mice, and irradiated normal mice. In all three recipients, the absolute number of recovered cells was much smaller than in normal mice. In addition, transferred naive T cells acquired a memory-like phenotype that remained stable with time. Finally, injected cells were rapidly replaced by host thymic migrants in irradiated normal mice. Only continuous output of naive T cells by the thymus can generate a full compartment of truly naive T cells. Thus, conversion of naive T cells to a memory-like phenotype in lymphopenic hosts is not related to a homeostatic mechanism that fills the peripheral naive T cell pool.

Expression and function of galectin-3, a beta-galactoside-binding protein in activated T lymphocytes

A soluble beta-galactoside-binding lectin, galectin-3 has been shown to be involved in cell adhesion and activation of immune cells. Although galectin-3 is known to be expressed in various types of cells, it has not been shown whether galectin-3 is expressed in T lymphocytes. We present evidence here that galectin-3 is expressed in activated murine T lymphocytes including CD4+ and CD8+ T cells but not in resting T cells. Galectin-3 expression was induced by anti-CD3 mAb or mitogen and enhanced by common gamma-chain signaling cytokines, IL-2, IL-4, and IL-7, in activated T lymphocytes, whereas the inflammatory cytokines including TNF-alpha and IFN-gamma did not. Galectin-3 expression and proliferation were down-regulated by withdrawal of IL-2 and gamma irradiation. Antisense but not sense phosphorothioated oligonucleotides for galectin-3 inhibited galectin-3 expression and blocked proliferation of T cells significantly. This study suggests that up-regulation of galectin-3 plays an important role in proliferation of activated T lymphocytes.

Bone marrow aplasia induced by passenger leukocytes from heart allografts

OBJECTIVE

Organ allografts contain passenger leukocytes that are transferred to the recipient with the transplantation, but their functional relevance to the recipient's immune system is still controversial.

MATERIALS AND METHODS

To clarify the functional capacity of passenger leukocytes, we attempted to enhance their effect in rat heart allograft recipients by selective depletion of recipient leukocytes using a monoclonal antibody (mAb) against a recipient-specific allotype of CD45 (RT7(a)).

RESULTS

Although antibody treatment of the recipient alone led to profound lymphopenia and reversible myelosuppression, additional transplantation of an major histocompatibility complex-incompatible heart graft from an RT7(b) donor led to lethal aplastic anemia in the recipients. This lethal effect was completely abrogated by postoperative anti-CD3 treatment of the recipient and was partially abrogated or delayed by depletion of passenger leukocytes through additional anti-RT7(b) antibody treatment of the recipient or gamma-irradiation of the graft.

CONCLUSIONS

The results suggest a role for both donor and recipient-type T cells for the induction of aplastic anemia in this model. The study shows that, under defined conditions, allogeneic passenger leukocytes in a heart graft can have a profound effect on the recipient's immune system and bone marrow.

CTLA4Ig-induced linked regulation of allogeneic T cell responses

The mechanisms by which CTLA4Ig exerts its powerful immunomodulatory effects are not clear. We show here that CTLA4Ig can induce linked regulation of allogeneic porcine T cell responses in vitro. Naive miniature swine SLA(dd) T cells were rendered hyporesponsive to specific allogeneic Ag after coculturing with MHC-mismatched SLA(cc) stimulators in the presence of CTLA4Ig. These Ag-specific hyporesponsive T cells were subsequently able to actively inhibit the allogeneic responses of naive syngeneic T cells in an MHC-linked fashion, as the responses of naive SLA(dd) responders against specific SLA(cc) and (SLA(ac))F(1) stimulators were inhibited, but allogeneic responses against a 1:1 mixture of SLA(aa) (I(a), II(a)) and SLA(cc) (I(c), II(c)) were maintained. This inhibition could be generated against either class I or class II Ags, was radiosensitive, and required cell-cell contact. Furthermore, the mechanism of inhibition was not dependent upon a deletional, apoptotic pathway, but it was reversed by anti-IL-10 mAb. These data suggest that CTLA4Ig-induced inhibition of naive allogeneic T cell responses can be mediated through the generation of regulatory T cells via an IL-10-dependent mechanism.

Characteristics of the Immunosuppression Induced by Cutaneous Photodynamic Therapy: Persistence, Antigen Specificity and Cell Type Involved¶

Relatively little is known about the immunosuppression induced in mice which have received cutaneous photodynamic therapy (PDT). Consequently, experiments were undertaken using mice which received dorsal PDT using Photofrin as the photosensitizer in an attempt to characterize the overall nature of the immunosuppression. Photoirradiation of mice at various times after injection indicated there was no correlation between photosensitivity and immunosuppression. The suppression was found to be adoptively transferable and antigen specific suggesting the generation of suppressor cells. Selective cell depletions prior to adoptive transfer indicated a CD4+ T cell to be responsible for the immunosuppression. Interestingly, using allogeneic spleen cells, no effect on the delayed type hypersensitivity (DTH) response was found. The results indicate that the suppression induced by cutaneous PDT, with the exception of the lack of DTH suppression, is similar to that induced by UVB irradiation but unlike that reported using laser PDT of the peritoneal cavity. This suggests that not only the type of photoirradiation but also the site of photoirradiation might determine the character of the induced immunosuppression.

On the self-referential nature of naive MHC class II-restricted T cells

The use of mutant mice expressing a normal MHC class II molecule surface level but a severely restricted self-peptide diversity (H-2Malpha(-/-)) previously revealed that T cells carrying the Ealpha(52-68)-I-A(b) complex-specific 1H3.1 TCR rely on self-peptide(s) recognition for both their peripheral persistence in irradiated hosts and their intrathymic positive selection. Here, we identify Ealpha(52-68) structurally related self-peptide(s) as a major contributor to in vivo positive selection of 1H3.1 TCR-transgenic thymocytes in I-A(b+)/I-Ealpha(-) mice. This is demonstrated by the drastic and specific reduction of the TCR high thymocyte population in 1H3.1 TCR-transgenic (Tg) mice treated with the Ealpha(52-68)-I-A(b) complex-specific Y-Ae mAb. Self-peptide(s) recognition is also driving the maturation of T cells carrying a distinct MHC class II-restricted specificity (the Ealpha(6) alphass TCR), since positive selection was also deficient in Ealpha(6) TCR Tg H-2Malpha(-/-) thymi. Such a requirement for recognition of self-determinants was mirrored in the periphery; Ealpha(6) TCR Tg naive T cells showed an impaired persistence in both H-2Malpha(-/-) and I-A(b)ss(-/-) irradiated hosts, whereas they persisted and slowly cycled in wild-type recipients. This moderate self-peptide(s)-dependent proliferation was associated with a surface phenotype intermediate between those of naive and activated/memory T cells; CD44 expression was up-regulated, but surface expression of other markers such as CD62L remained unaltered. Collectively, these observations indicate that maturation and maintenance of naive MHC class II-restricted T cells are self-oriented processes.

The effects of prolonged administration of 5-bromodeoxyuridine on cells of the immune system

We have determined the in vivo effect of 5-bromodeoxyuridine (BrdU) administered to mice in the drinking water for various lengths of time on the performance of T and B lymphocytes in a number of experimental protocols. Young mice continuously exposed to BrdU fail to gain weight, and the lymphocytes recovered after a prolonged period of exposure are fewer in number than in control mice. The recovery of normal levels of T and B lymphocytes after irradiation is severely impaired. Ag-specific cells responding to Ag in an adoptive transfer model fail to expand as much in the presence of BrdU as in the absence, and the Ag-specific effectors produced in the presence of BrdU are less able to secrete cytokines upon restimulation in vitro. Polarized populations of Tc1 and Tc2 effectors generated in vitro proliferate less in the presence of BrdU, and the resulting effectors make less cytokines per cell upon restimulation. Thus, the incorporation of BrdU into T or B lymphocytes can, under some circumstances, seriously impair the performance of the labeled cells, and these findings raise a note of caution in the interpretation of studies that make use of long-term exposure to BrdU.

NK-mediated elimination of mutant lymphocytes that have lost expression of MHC class I molecules

Mutant cells generated in vivo can be eliminated when mutated gene products are presented as altered MHC/peptide complexes and recognized by T cells. Diminished expression of MHC/peptide complexes enables mutant cells to escape recognition by T cells. In the present study, we tested the hypothesis that mutant lymphocytes lacking expression of MHC class I molecules are eliminated by autologous NK cells. In H-2b/k F1 mice, the frequency of H-2Kb-negative T cells was higher than that of H-2Kk-negative T cells. The frequency of H-2K-deficient T cells increased transiently after total body irradiation. During recovery from irradiation, H-2Kk-negative T cells disappeared more rapidly than H-2Kb-negative T cells. The disappearance of H-2K-deficient T cells was inhibited by administration of Ab against asialo-GM1. H-2Kk-negative T cells showed higher sensitivity to autologous NK cells in vitro than H-2Kb/k heterozygous or H-2Kb-negative T cells. Adding syngeneic NK cells to in vitro cultures prevented emergence of mutant cells lacking H-2Kk expression but had little effect on the emergence of mutant cells lacking H-2Kb expression. Results in the H-2b/k F1 strain correspond with the sensitivity of parental H-2-homozygous cells in models of marrow graft rejection. In H-2b/d F1 mice, there was no significant difference between the frequencies of H-2Kb-negative and H-2Kd-negative T cells, although the frequencies of mutant cells were different after radiation exposure among the strains examined. H-2b/d F1 mice also showed rapid disappearance of the mutant T cells after irradiation, and administration of Ab against asialo-GM1 inhibited the disappearance of H-2K-deficient T cells in H-2b/d F1 mice. Our results provide direct evidence that autologous NK cells eliminate mutant cell populations that have lost expression of self-MHC class I molecules.

Evidence for functional relevance of CTLA-4 in ultraviolet-radiation-induced tolerance

Hapten sensitization through UV-exposed skin induces hapten-specific tolerance that can be adoptively transferred by injecting T lymphocytes into naive recipients. The exact phenotype of T cells responsible for inhibiting the immune response and their mode of action remain unclear. Evidence exists that CTLA-4 negatively regulates T cell activation. We addressed whether CTLA-4 is involved in the transfer of UV-induced tolerance. Injection of lymph node cells from mice that were sensitized with dinitrofluorobenzene (DNFB) through UV-irradiated skin inhibited induction of contact hypersensitivity against DNFB in the recipient animals. When CTLA-4+ cells were depleted, transfer of suppression was lost. Likewise, significantly fewer lymphocytes enriched for CTLA-4+ cells were necessary to transfer suppression than unfractionated cells. Expression of CTLA-4 appears to be functionally relevant, since in vivo injection of a blocking anti-CTLA-4 Ab was able to break UV-induced tolerance and inhibited transfer of suppression. Upon stimulation with dendritic cells in the presence of the water-soluble DNFB analogue, DNBS, CTLA-4+ T cells from DNFB-tolerized mice secreted high levels of IL-10, TGF-beta, and IFN-gamma; low levels of IL-2; and no IL-4, resembling the cytokine pattern of T regulatory 1 cells. Ab blocking of CTLA-4 resulted in inhibition of IL-10 release. Accordingly, transfer of tolerance was not observed when recipients were treated with an anti-IL-10 Ab. Hence we propose that T cells, possibly of the T regulatory 1 type, transfer UV-mediated suppression through the release of IL-10. Activation of CTLA-4 appears to be important in this process.

Human bronchial intraepithelial T lymphocytes as a distinct T-cell subset: their long-term survival in SCID-Hu chimeras

Intestinal intraepithelial T lymphocytes (i-IELs) show features different from those of conventional T cells and play specific roles in the mucosal immunity. To investigate whether human bronchial intraepithelial T lymphocytes (IELs) are a distinct entity, we examined T cells in human bronchial xenografts transplanted on mice with severe combined immune deficiency (SCID). We transplanted human bronchi subcutaneously into mice with SCID, resected the xenografts after various incubation periods (7-174 d), and examined them for CD3(+), CD4(+), CD8(+), and CD45(+) cells by immunohistochemistry. The number of CD3(+) cells in the lamina propria decreased significantly in the first month (from 308.7 +/- 60.2 to 70.9 +/- 49. 4/mm(2); P < 0.05), and xenografts more than 5 mo of age had scant T cells in the lamina propria (5.2 +/- 2.0/mm(2)). However, there was no significant difference between the number of CD3(+) IELs in freshly isolated bronchi and in xenografts maintained for more than 5 mo. In freshly isolated bronchi, the number of CD4(+) IELs was significantly lower than that of CD8(+) cells (2.35 +/- 0.62 versus 4.56 +/- 1.32/mm basement membrane; P < 0.01). After transplantation, the mean CD4-to-CD8 ratio of all xenografts was significantly higher than that of freshly isolated bronchi (5.2 +/- 0.9 versus 0.6 +/- 0.2; P < 0.005). The IELs were positive for CD45, which is specific for human leukocytes, and they were eliminated by irradiation before the transplantation. Almost all IELs (99.5%) in the xenografts expressed alphabeta T-cell receptor, and 35.8% of IELs expressed alpha(e)beta7 integrin. Bronchial epithelial cells in the xenografts expressed interleukin (IL)-7, stem cell factor, intercellular adhesion molecule (ICAM)-1, and human leukocyte antigen-DR (HLA-DR). We conclude that in the SCID-Hu chimera model, human bronchial IELs survive for more than 5 mo, unlike the T cells in the lamina propria, and we suggest that human bronchial IELs may be stimulated by bronchial epithelial cells expressing IL-7, stem cell factor, ICAM-1, and HLA-DR.

Effects of UVB radiation on cytokine generation, cell adhesion molecules, and cell activation markers in T-lymphocytes and peripheral blood HPCs

BACKGROUND

Immunomodulatory effects of UV light have increasingly become a focus in transfusion medicine, BMT and transplantation immunology. In the transplant setting, the use of UVB radiation may reduce or abolish T-cell activation without compromising either bone marrow (BM) engraftment or graft-versus-leukemia effect. In this study, BM and apheresis-derived peripheral blood HPCs were used to investigate the effects of UVB on colony-forming ability, CD34+ cell viability, and growth potential, as well as on the secretion of MNC cytokines and the expression of cell surface markers and adhesion molecules.

STUDY DESIGN AND METHODS

After UVB radiation, enriched populations of T cells and antigen-presenting cells (APCs) were treated with PHA, and the MNC response was measured, as was colony-forming ability. CD34+ cells were quantified and their growth potential was determined in culture. Next, T-cell activation status, cell adhesion molecule and cell surface activation marker expression, and cytokine profiles were evaluated, and cytokine mRNA was quantitated. Parallel studies were done in unirradiated control cell populations.

RESULTS

Low-dose (10 mJ/cm(2)) UVB mitigates MNC proliferative responses by 94 percent while maintaining 60 and 80 percent of colony-forming ability in peripheral blood HPC and BM preparations, respectively, and >50 percent of colony-forming ability in CD34+ cell-enriched samples. Low-dose UVB radiation also significantly reduces T-cell production of TNFalpha, TNFalpha mRNA, TNFbeta, IL-2, and IL-6 and downregulates T-cell expression of CD28, CD25, CD69, and intercellular adhesion molecule 1.

CONCLUSION

These findings have shown that a "window" of low-dose UVB radiation (10 mJ/cm(2)) exists, at which BM- and peripheral blood-derived MNC proliferation is inactivated, while the HPCs are relatively spared. UVB light selectively affects T cells, while APCs are resistant to low doses of UVB. UVB radiation also alters the expression of some cell surface markers and cytokines that are important in T-cell activation pathways. Reduction of T-cell activation without cytocidal effect may allow UVB radiation to become an immunomodulating agent in BM or HPC transplantation.

Flow cytometric analysis of thymocyte subpopulations in mice after whole-body X-irradiation

To determined the cellular kinetics of thymocyte subpopulations in DBA1 mice after whole-body 6.8 Gy X-irradiation, they were analyzed for the expression of several cell surface antigens using flow cytometry. The results show that i) The majority of thymocytes rapidly depleted by irradiation was CD4+8+ cells. ii) radioresistant CD4+8- and CD4-8+ survived 18-48 hr after X-irradiation were considered to be relatively mature type, since they expressed high levels of CD3 and LECAM-1. iii) CD3-positive cells were detected in CD4-8- cells at 72 hr after irradiation.

Critical role of leukocyte function-associated antigen-1 in liver accumulation of CD4+NKT cells

In contrast to peripheral lymphoid organs, a high percentage of T cells in the liver are CD4+NKT cells. We asked whether adhesion molecules play any role in the accumulation of CD4+NKT cells in the liver. Liver CD4+NKT cells expressed ICAM-1 and high levels of LFA-1. In the livers of LFA-1-deficient mice, the number of CD4+NKT cells was markedly decreased. This reduction was restricted to the liver, and no reduction was found in the other organs analyzed. In contrast, the number of liver CD4+NKT cells in ICAM-1-deficient mice was only marginally reduced. In a reciprocal radiation thymocyte reconstitution system with LFA-1-deficient and wild-type mice, LFA-1 expressed on liver cells other than CD4+NKT cells was required for an accumulation of CD4+NKT cells in the liver. These results demonstrate a crucial role for LFA-1 in the accumulation of CD4+NKT cells in the liver.