Critical Review-A Tribute to Louis Brocq Lymphomatoid Papulosis, the Key in Exploring the Relationship of Parapsoriasis and Mycosis Fungoides

ABSTRACT

Both parapsoriasis and LyP appear clinically as inflammatory dermatoses with a paradoxical link to cMF. A key element in addressing the relationship of parapsoriasis and MF were the results of the French and Dutch long-term registries tracking the emergence of lymphomas in the setting of LyP. Both cMF and cALCL emerged almost equally in these long-term studies. This ultimately supports that the stem cells in both cMF and cALCL are probably derived from a common stem cell shared by CD4+/CD8+ memory stem cells defining cMF and CD30+ stem cells defining cALCL. The discovery of inducible Skin Associated Lymphoid Tissue (iSALT) mesenchymal hubs incorporating Tregs, with their pleiotropic functions represents a paradigm shift and formed a translational tool in this analysis of the paradox. LyP can be recast as activated inhibitory lymphomatoid T-cell hubs derived from inducible iTregs in iSALT and the source of the common stem cell LyP line. iSALT Treg integrated mesenchymal hubs provided an emerging translational tool in redefining integrated lymphomatoid pathways. Brocq's complex scheme defining parapsoriasis as hybrid inflammatory dermatoses with a paradoxical link to cMF became a template to preserve parapsoriasis as a clinical diagnosis. Two major iSALT Treg generated inhibitory integrated lymphomatoid hubs emerged. The major CD30+TNF lymphomatoid hub has been linked to cALCL. Clinically defined chronic regressing and relapsing parapsoriasis with the histopathology of patch stage MF can be redefined as lymphomatoid parapsoriasis. This twin inhibited oncogenic memory based hub is defined by Treg modulated, CD4+/CD8+memory linked PD-1/DL-1 cytoxic complex and lichenoid histopathology.

Differences in Immune phenotype in decidual tissue from multigravid women compared to primigravid women

PROBLEM

Women with a previous uncomplicated pregnancy have lower risks of immune-associated pregnancy disorders in a subsequent pregnancy. This could indicate a different maternal immune response in multigravid women compared to primigravid women. In a previous study, we showed persistent higher memory T cell proportions with higher CD69 expression after uncomplicated pregnancies. To our knowledge no studies have reported on immune cells in general, and immune memory cells and macrophages specifically in multigravid and primigravid women.

METHOD OF STUDY

T cells and macrophages were isolated from term decidua parietalis and decidua basalis tissue from healthy primigravid women (n = 12) and multigravid women (n = 12). Using flow cytometry, different T cell populations including memory T cells and macrophages were analyzed. To analyze whether a different immune phenotype is already present in early pregnancy, decidual tissue from uncomplicated ongoing pregnancies between 9 and 12 weeks of gestation from multigravida and primigravid women was investigated using qRT-PCR.

RESULTS

Nearly all T cell subsets analyzed in the decidua parietalis had significantly higher CD69⁺ proportions in multigravid women compared to primigravid women. A higher proportion of decidual (CD50^- ) M2-like macrophages was found in the decidua parietalis in multigravid women compared to primigravid women. In first trimester decidual tissue higher FOXP3 mRNA expression was found in multigravid women compared to primigravid women.

CONCLUSIONS

This study shows that decidual tissue from multigravid women has a more activated and immunoregulatory phenotype compared to decidual tissue from primigravid women in early pregnancy and at term which could suggest a more balanced immune adaptation towards pregnancy after earlier uncomplicated pregnancies.

B cells expressing IL-10 mRNA modulate memory T cells after DNA-Hsp65 immunization

In DNA vaccines, the gene of interest is cloned into a bacterial plasmid that is engineered to induce protein production for long periods in eukaryotic cells. Previous research has shown that the intramuscular immunization of BALB/c mice with a naked plasmid DNA fragment encoding the Mycobacterium leprae 65-kDa heat-shock protein (pcDNA3-Hsp65) induces protection against M. tuberculosis challenge. A key stage in the protective immune response after immunization is the generation of memory T cells. Previously, we have shown that B cells capture plasmid DNA-Hsp65 and thereby modulate the formation of CD8+ memory T cells after M. tuberculosis challenge in mice. Therefore, clarifying how B cells act as part of the protective immune response after DNA immunization is important for the development of more-effective vaccines. The aim of this study was to investigate the mechanisms by which B cells modulate memory T cells after DNA-Hsp65 immunization. C57BL/6 and BKO mice were injected three times, at 15-day intervals, with 100 µg naked pcDNA-Hsp65 per mouse. Thirty days after immunization, the percentages of effector memory T (TEM) cells (CD4+ and CD8+/CD44high/CD62Llow) and memory CD8+ T cells (CD8+/CD44high/CD62Llow/CD127+) were measured with flow cytometry. Interferon γ, interleukin 12 (IL-12), and IL-10 mRNAs were also quantified in whole spleen cells and purified B cells (CD43-) with real-time qPCR. Our data suggest that a B-cell subpopulation expressing IL-10 downregulated proinflammatory cytokine expression in the spleen, increasing the survival of CD4+ TEM cells and CD8+ TEM/CD127+ cells.

Complete remission of cancer in late-stage disease by radiation and transfer of allogeneic MHC-matched immune T cells: lessons from GvL studies in animals

Most immunotherapy studies in animal tumor models are performed in early stages of the disease. Reports on the studies of treatment in late stages of tumor growth and metastasis are much rarer. To guide future efforts for treatment in late-stage disease, a model of effective immune rejection of advanced metastasized cancer is reviewed and lessons therefrom are summarized. Already cachectic DBA/2 mice with a subcutaneously transplanted syngeneic tumor (ESb-MP lymphoma) of 1.5 cm diameter and with macroscopic liver and kidney metastases at 4 weeks could be successfully treated by a combination of sublethal (5 Gy) irradiation followed by a single transfer of 20 million anti-tumor immune spleen cells from tumor-resistant allogeneic MHC-B10.D2 mice. Following intravenous cell transfer, the primary tumors became encapsulated and were eventually rejected from the skin while visceral metastases gradually disappeared leaving behind only scar tissue. There was wound-healing at the site of the rejected primary tumor, and the animals survived long term without any tumor recurrence. The complete eradication of late-stage disease by adoptive cellular immunotherapy could be corroborated noninvasively by (31)P-NMR spectroscopy of primary tumors and by (1)H-NMR microimaging of liver metastases. Conclusions from functional mechanistic studies in this model are summarized and clinical implications discussed.

Cytotoxic response persists in subjects treated for tuberculosis decades ago

BACKGROUND

Data exploring the potential use of effector molecules produced by cytotoxic T lymphocytes (CTLs) in the immunodiagnostics of tuberculosis (TB) are scarce. The present study focused a) to gain an insight into the discriminatory power of CTLs in patients with acute pulmonary or extra-pulmonary TB, or latent tuberculosis infection (LTBI); and b) to evaluate the influence of various anti-TB therapeutic schemes on the immunological profiles of residual CTLs.

METHODS

Immunological signatures of antigen-specific CTLs were explored in patients with active pulmonary and extra-pulmonary TB, LTBI and in those treated for TB decades ago by using ELISPOT, intracellular flow cytometry and extracellular CD107a detection.

RESULTS

No difference was seen between active TB, LTBI or any of those treated for TB in the ELISPOT analysis of antigen-specific Granzyme B (GrB), Perforin (Prf) and interferon-gamma (IFN-γ) producing lymphocytes, the FACS analysis of the intracellular expression of IFN-γ, or the surface expression of CD107a degranulation factor of both CD8+ and CD4+ antigen-specific T cell subsets. The effector memory (TEM) phenotype proved predominant in the surface marker profiling both in active TB and LTBI. The proportion of the CD107a degranulation factor proved higher in the central memory (TCM) than in the other cell subsets in all the study groups. Interestingly, functionally and phenotypically similar CTLs profiles were observed in active TB, LTBI and in all the three groups treated for TB.

CONCLUSION

The phenotypic and functional profiling of CTLs has a limited potential in the immunodiagnostics of active TB. Antigen-specific CTLs persist in patients treated for TB decades ago regardless of the efficacy of implemented and completed anti-TB therapy.

An introduction to mass cytometry: fundamentals and applications

Mass cytometry addresses the analytical challenges of polychromatic flow cytometry by using metal atoms as tags rather than fluorophores and atomic mass spectrometry as the detector rather than photon optics. The many available enriched stable isotopes of the transition elements can provide up to 100 distinguishable reporting tags, which can be measured simultaneously because of the essential independence of detection provided by the mass spectrometer. We discuss the adaptation of traditional inductively coupled plasma mass spectrometry to cytometry applications. We focus on the generation of cytometry-compatible data and on approaches to unsupervised multivariate clustering analysis. Finally, we provide a high-level review of some recent benchmark reports that highlight the potential for massively multi-parameter mass cytometry.

Longitudinal changes in CD4(+) T-cell memory responses induced by BCG vaccination of newborns

BACKGROUND

Improved vaccination strategies against tuberculosis are needed, such as approaches to boost immunity induced by the current vaccine, BCG. Design of these strategies has been hampered by a lack of knowledge of the kinetics of the human host response induced by neonatal BCG vaccination. Furthermore, the functional and phenotypic attributes of BCG-induced long-lived memory T-cell responses remain unclear.

METHODS

We assessed the longitudinal CD4 T-cell response following BCG vaccination of human newborns. The kinetics, function, and phenotype of these cells were measured using flow cytometric whole-blood assays.

RESULTS

We showed that the BCG-specific CD4 T-cell response peaked 6-10 weeks after vaccination and gradually waned over the first year of life. Highly activated T-helper 1 cells, predominantly expressing interferon γ, tumor necrosis factor α, and/or interleukin 2, were present at the peak response. Following contraction, BCG-specific CD4 T cells expressed high levels of Bcl-2 and displayed a predominant CD45RACCR7 central memory phenotype. However, cytokine and cytotoxic marker expression by these cells was more characteristic of effector memory cells.

CONCLUSIONS

Our findings suggest that boosting of BCG-primed CD4 T cells with heterologous tuberculosis vaccines may be best after 14 weeks of age, once an established memory response has developed.

Pretransplant antithymocyte globulin has increased efficacy in controlling donor-reactive memory T cells in mice

Antibody-mediated lymphocyte depletion is frequently used as induction therapy in sensitized transplant patients. Although T cells with an effector/memory phenotype remain detectable after lymphoablative therapies in human transplant recipients, the role of preexisting donor-reactive memory in reconstitution of the T cell repertoire and induction of alloimmune responses following lymphoablation is poorly understood. We show in a mouse cardiac transplantation model that antidonor immune responses following treatment with rabbit antimouse thymocyte globulin (mATG) were dominated by T cells derived from the preexisting memory compartment. Administration of mATG 1 week prior to transplantation (pre-TP) was more efficient in targeting preexisting donor-reactive memory T cells, inhibiting overall antidonor T cell responses, and prolonging heart allograft survival than the commonly used treatment at the time of transplantation (peri-TP). The failure of peri-TP mATG to control antidonor memory responses was due to faster recovery of preexisting memory T cells rather than their inefficient depletion. This rapid recovery did not depend on T cell specificity for donor alloantigens suggesting an important role for posttransplant inflammation in this process. Our findings provide insights into the components of the alloimmune response remaining after lymphoablation and may help guide the future use of ATG in sensitized transplant recipients.

Evidence for a role for the adaptive immune response in human term parturition

PROBLEM

Spontaneous labor at term involves leukocyte recruitment and infiltration into the choriodecidua; yet, characterization of these leukocytes and their immunological mediators is incomplete. The purpose of this study was to characterize the immunophenotype of choriodecidual leukocytes as well as the expression of inflammatory mediators in human spontaneous parturition at term.

METHOD OF STUDY

Choriodecidual leukocytes were analyzed by FACS, immunohistochemistry, and RT-PCR in three different groups: (i) preterm gestation delivered for medical indications without labor; (ii) term pregnancy without labor; and (iii) term pregnancy after spontaneous labor.

RESULTS

Two T-cell subsets of memory-like T cells (CD3(+) CD4(+) CD45RO(+) and CD3(+) CD4(-) CD8(-) CD45RO(+) cells) were identified in the choriodecidua of women who had spontaneous labor. Evidence for an extensive immune signaling network composed of chemokines (CXCL8 and CXCL10), chemokine receptors (CXCR1-3), cytokines (IL-1β and TNF-α), cell adhesion molecules, and MMP-9 was identified in these cells during spontaneous labor at term.

CONCLUSIONS

The influx of memory-like T cells in the choriodecidua and the evidence that they are active by producing chemokines and cytokines, and expressing chemokine receptors, cell adhesion molecules, and a matrix-degrading enzyme provides support for the participation of the adaptive immune system in the mechanisms of spontaneous parturition at term.

Cathepsin B controls the persistence of memory CD8+ T lymphocytes

The persistence of memory T lymphocytes confers lifelong protection from pathogens. Memory T cells survive and undergo homeostatic proliferation (HSP) in the absence of Ag, although the cell-intrinsic mechanisms by which cytokines drive the HSP of memory T cells are not well understood. In this study we report that lysosome stability limits the long-term maintenance of memory CD8(+) T cell populations. Serine protease inhibitor (Spi) 2A, an anti-apoptotic cytosolic cathepsin inhibitor, is induced by both IL-15 and IL-7. Mice deficient in Spi2A developed fewer memory phenotype CD44(hi)CD8(+) T cells with age, which underwent reduced HSP in the bone marrow. Spi2A was also required for the maintenance of central memory CD8(+) T cell populations after acute infection with lymphocytic choriomeningitis virus. Spi2A-deficient Ag-specific CD8(+) T cell populations declined more than wild-type competitors after viral infection, and they were eroded further after successive infections. Spi2A protected memory cells from lysosomal breakdown by inhibiting cathepsin B. The impaired maintenance of Spi2A-deficient memory CD8(+) T cells was rescued by concomitant cathepsin B deficiency, demonstrating that cathepsin B was a physiological target of Spi2A in memory CD8(+) T cell survival. Our findings support a model in which protection from lysosomal rupture through cytokine-induced expression of Spi2A determines the long-term persistence of memory CD8(+) T cells.

Overcoming memory T-cell responses for induction of delayed tolerance in nonhuman primates

The presence of alloreactive memory T cells is a major barrier for induction of tolerance in primates. In theory, delaying conditioning for tolerance induction until after organ transplantation could further decrease the efficacy of the regimen, since preexisting alloreactive memory T cells might be stimulated by the transplanted organ. Here, we show that such "delayed tolerance" can be induced in nonhuman primates through the mixed chimerism approach, if specific modifications to overcome/avoid donor-specific memory T-cell responses are provided. These modifications include adequate depletion of CD8+ memory T cells and timing of donor bone marrow administration to minimize levels of proinflammatory cytokines. Using this modified approach, mixed chimerism was induced successfully in 11 of 13 recipients of previously placed renal allografts and long-term survival without immunosuppression could be achieved in at least 6 of these 11 animals.

Integrin antagonists prevent costimulatory blockade-resistant transplant rejection by CD8(+) memory T cells

The success of belatacept in late-stage clinical trials inaugurates the arrival of a new class of immunosuppressants based on costimulatory blockade, an immunosuppression strategy that disrupts essential signals required for alloreactive T-cell activation. Despite having improved renal function, kidney transplant recipients treated with belatacept experienced increased rates of acute rejection. This finding has renewed focus on costimulatory blockade-resistant rejection and specifically the role of alloreactive memory T cells in mediating this resistance. To study the mechanisms of costimulatory blockade-resistant rejection and enhance the clinical efficacy of costimulatory blockade, we developed an experimental transplant system that models a donor-specific memory CD8(+) T-cell response. After confirming that graft-specific memory T cells mediate costimulatory blockade-resistant rejection, we characterized the role of integrins in this rejection. The resistance of memory T cells to costimulatory blockade was abrogated when costimulatory blockade was coupled with either anti-VLA-4 or anti-LFA-1. Mechanistic studies revealed that in the presence of costimulatory blockade, anti-VLA-4 impaired T-cell trafficking to the graft but not memory T-cell recall effector function, whereas anti-LFA-1 attenuated both trafficking and memory recall effector function. As antagonists against these integrins are clinically approved, these findings may have significant translational potential for future clinical transplant trials.

Relative resistance of human CD4(+) memory T cells to suppression by CD4(+) CD25(+) regulatory T cells

Successful expansion of functional CD4(+) CD25(+) regulatory T cells (T(reg)) ex vivo under good manufacturing practice conditions has made T(reg) -cell therapy in clinical transplant tolerance induction a feasible possibility. In animals, T(reg) cells home to both transplanted tissues and local lymph nodes and are optimally suppressive if active at both sites. Therefore, they have the opportunity to suppress both naïve and memory CD4(+) CD25(-) T cells (Tresp). Clinical transplantation commonly involves depleting therapy at induction (e.g. anti-CD25), which favors homeostatic expansion of memory T cells. Animal models suggest that T(reg) cells are less suppressive on memory, compared with naïve Tresp that mediate allograft rejection. As a result, in the context of human T(reg) -cell therapy, it is important to define the effectiveness of T(reg) cells in regulating naïve and memory Tresp. Therefore, we compared suppression of peripheral blood naïve and memory Tresp by fresh and ex vivo expanded T(reg) cells using proliferation, cytokine production and activation marker expression (CD154) as readouts. With all readouts, naïve human Tresp were more suppressible by approximately 30% than their memory counterparts. This suggests that T(reg) cells may be more efficacious if administered before or at the time of transplantation and that depleting therapy should be avoided in clinical trials of T(reg) cells.

Chronic alcohol consumption enhances myeloid-derived suppressor cells in B16BL6 melanoma-bearing mice

We previously found that chronic alcohol consumption decreases the survival of mice bearing subcutaneous B16BL6 melanoma. The underlying mechanism is still not completely understood. Antitumor T cell immune responses are important to inhibiting tumor progression and extending survival. Therefore, we examined the effects of chronic alcohol consumption on the functionality and regulation of these cells in C57BL/6 mice that chronically consumed 20% (w/v) alcohol and subsequently were inoculated subcutaneously with B16BL6 melanoma cells. Chronic alcohol consumption inhibited melanoma-induced memory T cell expansion and accelerated the decay of interferon (IFN)-gamma producing T cells in the tumor-bearing mice. Foxp3(+)CD4(+)CD25(+) regulatory T cells were not affected; however, the percentage of myeloid-derived suppressor cells (MDSC) was significantly increased in the peripheral blood and spleen. T cell proliferation as determined by carboxyfluorescein succinimidyl ester labeling experiments in vitro was inhibited by alcohol consumption relative to control water-drinking melanoma-bearing mice. Collectively, these data show that chronic alcohol consumption inhibits proliferation of memory T cells, accelerates the decay of IFN-gamma producing CD8(+) T cells, and increases MDSC, all of which could be associated with melanoma progression and reduced survival.

Phenotype, distribution and alloreactive properties of memory T cells from cynomolgus monkeys

The high frequency of memory T cells present in primates is thought to represent a major barrier to tolerance induction in transplantation. Therefore, it is crucial to characterize these memory T cells and determine their functional properties. High numbers of memory T cells were detected in peripheral blood and all lymphoid tissues except lymph nodes, which were essentially the site of naïve T cells. The majority of CD8(+) memory T cells were effector memory cells located in the blood and bone marrow while most CD4(+) memory T cells were central memory cells present in the spleen. Next, memory T cells from over 100 monkeys were tested for their response to alloantigens by ELISPOT. Memory alloreactivity mediated via direct but not indirect allorecognition was detected in all animals. The frequency of allospecific memory T cells varied dramatically depending upon the nature of the responder/stimulator monkey combination tested. MHC gene matching was generally associated with a low-memory alloreactivity. Nevertheless, low anamnestic alloresponses were also found in a significant number of fully MHC-mismatched monkey combinations. These results show that selected donor/recipient combinations displaying a low memory alloresponsiveness can be found. These combinations may be more favorable for transplant tolerance induction.

Memory T-cell trafficking: new directions for busy commuters

The immune system is unique in representing a network of interacting cells of enormous complexity and yet being based on single cells travelling around the body. The development of effective and regulated immunity relies upon co-ordinated migration of each cellular component, which is regulated by diverse signals provided by the tissue. Co-ordinated migration is particularly relevant to the recirculation of primed T cells, which, while performing continuous immune surveillance, need to promptly localize to antigenic sites, reside for a time sufficient to carry out their effector function and then efficiently leave the tissue to avoid bystander damage. Recent advances that have helped to clarify a number of key molecular mechanisms underlying the complexity and efficiency of memory T-cell trafficking, including antigen-dependent T-cell trafficking, the regulation of T-cell motility by costimulatory molecules, T-cell migration out of target tissue and fugetaxis, are reviewed in this article.

Differential requirement of CD27 costimulatory signaling for naïve versus alloantigen-primed effector/memory CD8+ T cells

CD8(+) memory T cells endanger allograft survival by causing acute and chronic rejection and prevent tolerance induction. We explored the role of CD27:CD70 T-cell costimulatory pathway in alloreactive CD8(+)/CD4(+) T-cell activation. CD27-deficient (CD27(-/-)) and wild-type (WT) B6 mice rejected BALB/c cardiac allografts at similar tempo, with or without depletion of CD4(+) or CD8(+) T cells, suggesting that CD27 is not essential during primary T-cell alloimmune responses. To dissect the role of CD27 in primed effector and memory alloreactive T cells, CD27(-/-) or WT mice were challenged with BALB/c hearts either 10 or 40 days after sensitization with donor-type skin grafts. Compared to WT controls, allograft survival was prolonged in day 40- but not day 10-sensitized CD27(-/-) recipients. Improved allograft survival was accompanied by diminished secondary responsiveness of memory CD8(+) T cells, which resulted from deficiency in memory formation rather than their lack of secondary expansion. Chronic allograft vasculopathy and fibrosis were diminished in CD27(-/-) recipients of class I- but not class II-mismatched hearts as compared to WT controls. These data establish a novel role for CD27 as an important costimulatory molecule for alloreactive CD8(+) memory T cells in acute and chronic allograft rejection.

Gliadin-primed CD4+CD45RBlowCD25- T cells drive gluten-dependent small intestinal damage after adoptive transfer into lymphopenic mice

BACKGROUND AND AIMS

Coeliac disease is a common small intestinal inflammatory disorder that results from a breach of intestinal tolerance to dietary gluten proteins, driven by gluten-reactive effector T cells. We aimed to assess the pathogenic role of gluten-reactive T cells and to generate a model of gluten-induced enteropathy.

METHODS

CD4+CD25- T cell fractions were adoptively transferred into lymphopenic mice, leading to "baseline" small intestinal inflammation.

RESULTS

Rag1-/- recipients of gliadin-presensitised CD4+CD45RBlowCD25- T cells, but not CD4+CD45RBhigh naive T cells, gained less weight and suffered from more severe duodenitis when challenged with oral gluten than recipients on gluten-free diet, or recipients of control (ovalbumin)-presensitised T cells. This was accompanied by deterioration of mucosal histological features characteristic of coeliac disease, and increased Th1/Th17 cell polarisation in the duodenum and the periphery. Interestingly, reintroduction of a gluten-free diet led to weight gain, improvement of histological duodenitis, and a decrease in duodenal interferon gamma and interleukin 17 transcripts. Moreover, B cell-competent nude recipients of gliadin-presensitised CD4+CD45RBlowCD25- T cells produced high levels of serum anti-gliadin immunoglobulin A (IgA) and IgG1/IgG2c only when challenged with oral gluten.

CONCLUSIONS

CD4+ T cell immunity to gluten leads to a breach of oral gluten tolerance and small intestinal pathology in lymphopenic mice, similar to human coeliac disease. This model will be useful for the study of coeliac disease pathogenesis, and also for testing novel non-dietary therapies for coeliac disease.

Treatment of advanced metastasized breast cancer with bone marrow-derived tumour-reactive memory T cells: a pilot clinical study

BACKGROUND

Breast cancer patients frequently harbour tumour-reactive memory T cells in their bone marrow (BM) but not in the blood. After reactivation ex-vivo these cells rejected autologous breast tumours in xenotransplanted mice demonstrating therapeutic potential upon reactivation and mobilization into the blood. We conducted a clinical pilot study on metastasized breast cancer patients to investigate if ex-vivo reactivation of tumour-reactive BM memory T cells and their adoptive transfer is feasible and increases the frequencies of tumour-reactive T cells in the blood.

METHODS

The study protocol involved one transfusion of T cells which were reactivated in vitro with autologous dendritic cells pulsed with lysate of MCF7 breast cancer cells as source of tumour antigens. Immunomonitoring included characterization of T cell activation in vitro and of tumour-specific T cells in the blood by interferon (IFN)-gamma ELISPOT assay, HLA-tetramers and antigen-induced interleukin (IL)-4 secretion.

RESULTS

Twelve patients with pre-existing tumour-reactive BM memory T cells were included into the study. In all cases, the treatment was feasible and well tolerated. Six patients (responders) showed by ELISPOT assay de-novo tumour antigen-specific, IFN-gamma-secreting T cells in the blood after 7 days. In contrast, non responders showed in the blood tumour antigen-induced IL-4 responses. All responders received more than 6.5 x 10(3) tumour-reactive T cells. In contrast, all non responders received lower numbers of tumour antigen-reactive T cells. This was associated with reduced activation of memory T cells in activation cultures, increased amounts of CD4(+) CD25(high) regulatory T cells in the BM and increased tumour antigen-dependent IL-10 secretion. The latter was prevented by preceding depletion of regulatory T cells suggesting that regulatory T cells in the BM can inhibit reactivation of tumour-specific T cells.

CONCLUSION

Taken together, adoptive transfer of ex-vivo re-stimulated tumour-reactive memory T cells from BM of metastasized breast cancer patients can induce the presence of tumour antigen-reactive type-1 T cells in the peripheral blood.

IL-2 and IL-15 each mediate de novo induction of FOXP3 expression in human tumor antigen-specific CD8 T cells

Although FOXP3 is primarily expressed by regulatory CD4 T cells (Treg) in vivo, polyclonal activation of human CD8 T cells can result in the expression of FOXP3 in a fraction of CD8 T cells. However, the cellular lineage and mechanism of FOXP3 induction in CD8 T cells remain unclear. Here, we demonstrate that interleukin-2 (IL-2) induces FOXP3 expression in OKT3-stimulated or antigen-stimulated CD8 T cells, indicating that FOXP3 expression is neither limited to a unique subset of CD8 T cells nor dependent on the mode of T-cell receptor stimulation. In the absence of IL-2, antigen stimulation resulted in T-cell activation and acquisition of effector function without induction of FOXP3, indicating that acquisition of effector function is independent of induction of FOXP3 expression in CD8 T cells. Interestingly, IL-15, but not IL-7 or IL-21, also led to de novo induction of FOXP3 in antigen-specific CD8 T cells, suggesting that signaling by IL-2/IL-15Rbeta chain is pivotal for induction of FOXP3 in human CD8 T cells. These findings indicate that induction of FOXP3 is intrinsic to CD8 T cells that are activated in the presence of IL-2 or IL-15, and in vitro-induced expression of FOXP3 cannot be simply interpreted as an indicator of Treg activity or activation marker.

Analysis of naïve and memory CD4 and CD8 T cell populations in breast cancer patients receiving a HER2/neu peptide (E75) and GM-CSF vaccine

We are conducting clinical trials of the E75 peptide as a vaccine in breast cancer (BrCa) patients. We assessed T cell subpopulations in BrCa patients before and after E75 vaccination and compared them to healthy controls. We obtained 17 samples of blood from ten healthy individuals and samples from 22 BrCa patients prior to vaccination. We also obtained pre- and post-vaccination samples of blood from seven BrCa patients who received the E75/GM-CSF vaccine. CD4, CD8, CD45RA, CD45RO, and CCR7 antibodies were used to analyze the CD4+ and CD8+ T cells by four-color flow cytometry. Compared to healthy individuals, BrCa patients have significantly more memory and less naïve T cells and more effector-memory CD8+ and less effector CD4+ T cells. Phenotypic differences in defined circulating CD4+ and CD8+ T cell subpopulations suggest remnants of an active immune response to tumor distinguished by a predominant memory T cell response and by untapped recruitment of naïve helper and cytotoxic T cells. E75 vaccination induced recruitment of both CD4+ and CD8+ naïve T cells while memory response remained stable. Additionally, vaccination induced global activation of all T cells, with specific enhancement of effector CD4+ T cells. E75 vaccination causes activation of both memory and naïve CD4+ and CD8+ T cells, while recruiting additional naïve CD4+ and CD8+ T cells to the overall immune response.

Human memory T cell responses to SARS-CoV E protein

E protein is a membrane component of severe acute respiratory syndrome coronavirus (SARS-CoV). Disruption of E protein may reduce viral infectivity. Thus, the SARS-CoV E protein is considered a potential target for the development of antiviral drugs. However, the cellular immune responses to E protein remain unclear in humans. In this study, we found that peripheral blood mononuclear cells (PBMCs) from fully recovered SARS individuals rapidly produced IFN-gamma and IL-2 following stimulation with a pool of 9 peptides overlapping the entire E protein sequence. Analysis of the immune responses by flow cytometry showed that both CD4+ and CD8+T cells were involved in the SARS-CoV E-specific immune responses after stimulation with SARS-CoV E peptides. Moreover, the majority of IFN-gamma+CD4+T cells were central memory cells expressing CD45RO+CCR7+CD62L-; whereas IFN-gamma+CD8+ memory T cells were mostly effector memory cells expressing CD45RO-CCR7-CD62L-. The results of T-cell responses to 9 individual peptides indicated that the E protein contained at least two major T cell epitopes (E2 amino acid [aa] 9-26 and E5-6: aa 33-57) which were important in eliciting cellular immune response to SARS-CoV E protein in humans.

Long-lived memory T lymphocyte responses against SARS coronavirus nucleocapsid protein in SARS-recovered patients

The nucleocapsid (N) protein is a structural component of severe acute respiratory syndrome (SARS) coronavirus (SARS-CoV) and can induce antibody responses in SARS patients during infection. However, it is not known whether SARS-CoV N protein can induce a long persistence of memory T-cell response in human. In this study, we found that peripheral blood mononuclear cells (PBMCs) from fully recovered SARS individuals rapidly produced IFN-gamma and IL-2 following stimulation with a pool of overlapping peptides that cover the entire N protein sequence. The N-specific IFN-gamma(+)CD4(+) T cells were mainly composed of CD45RA(-)CCR7(+)CD62L(-) cells, whereas IFN-gamma(+)CD8(+) memory T cells were mostly contained within CD45RA(+)CCR7(-)CD62L(-) cell population. Epitope mapping study indicated that a cluster of overlapping peptides located in the C-terminal region (amino acids [aa] 331 to 362) of N protein contained at least two different T-cell epitopes. The results indicated that human memory T-cell responses specific for SARS-CoV N protein could persist for 2 years in the absence of antigen, which would be a valuable for the design of effective vaccines against SARS-CoV and for basic studies of human T-cell memory.

Bim mediates apoptosis of CD127(lo) effector T cells and limits T cell memory

Following an acute T cell response, most activated effector cells die, while some survive and become memory cells. The pro-apoptotic Bcl-2 family member, Bcl-2 interacting mediator of death (Bim) is critical for eliminating most effector T cells, while expression of CD127 (IL-7Ralpha) has been proposed to mark effector cells destined to become memory cells. Here, we examined the effects of Bim on the death of effector T cells in relationship to CD127 expression and on development of T cell memory following lymphocytic choriomeningitis virus (LCMV) infection. We found that large numbers of CD127(lo) LCMV-specific CD4(+) and CD8(+) T cells were lost in wild-type mice, but were spared in Bim(-/-) mice. Further, while the numbers of CD127(hi) T cells declined only slightly during contraction of the response in wild-type mice, they increased significantly in Bim(-/-) mice due to re-expression of CD127 on CD127(lo) T cells that had avoided apoptosis. Functional memory T cells were significantly increased in Bim(-/-) mice; however, they underwent a slow attrition due to decreased proliferative renewal. Taken together, these data suggest that the absence of Bim-mediated death of LCMV-specific CD4(+) and CD8(+) T cells in vivo can increase T cell memory, but other homeostatic mechanisms control the long-term maintenance of memory cells.

Life and death of lymphocytes: a role in immunesenescence

Human aging is associated with progressive decline in immune functions, increased frequency of infections. Among immune functions, a decline in T cell functions during aging predominates. In this review, we will discuss the molecular signaling in two major pathways of apoptosis, namely death receptor pathway and mitochondrial pathway, and their alterations in both T and B lymphocytes in human aging with a special emphasis on naïve and different memory subsets of CD8+ T cells. We will also discuss a possible role of lymphocyte apoptosis in immune senescence.

Clinical trials of antitumor vaccination with an autologous tumor cell vaccine modified by virus infection: improvement of patient survival based on improved antitumor immune memory

For active specific immunotherapy of cancer patients, we designed the autologous virus-modified tumor cell vaccine ATV-NDV. The rationale of this vaccine is to link multiple tumor-associated antigens (TAAs) from individual patient-derived tumor cells with multiple danger signals (DS) derived from virus infection (dsRNA, HN, IFN-alpha). This allows activation of multiple innate immune responses (monocytes, dendritic cells, and NK cells) as well as adaptive immune responses (CD4 and CD8 memory T cells). Preexisting antitumor memory T cells from cancer patients could be activated by antitumor vaccination with ATV-NDV as seen by augmentation of antitumor memory delayed-type hypersensitivity (DTH) responses. In a variety of phase II vaccination studies, an optimal formulation of this vaccine could improve long-term survival beyond what is seen in conventional standard therapies. A new concept is presented which proposes that a certain threshold of antitumor immune memory plays an important role (1) in the control of residual tumor cells which remain after most therapies and (2) for long-term survival of treated cancer patients. This immune memory is T-cell based and most likely maintained by persisting TAAs from residual dormant tumor cells. Such immune memory was prominent in the bone marrow in animal tumor models as well as in cancer patients. Immunization with a tumor vaccine in which individual TAAs are combined with DS from virus infection appears to have a positive effect on antitumor immune memory and on patient survival.

Delivery of antigen in allogeneic cells preferentially generates CD(4+) Th1 cells

We have examined the possibility of evoking antigen-specific T cell immune response by using allogeneic cells as a source of adjuvant and also as a vehicle to deliver antigen. The mice were immunized with different preparations of antigen-pulsed allogeneic and syngeneic splenocytes. It was observed during the study that the animals immunized with antigen-pulsed mitomycin C treated allogeneic cells elicited antigen specific CD(4+) Th1 cell response. Predominant release of IL-2, interferon (IFN)-gamma and IgG2a-isotype also occurred. In contrast, mice immunized with antigen-pulsed syngeneic cells chiefly enhanced the production of interleukin (IL)-4 and IgG1-isotype. Further, allogeneic macrophages induced better T cell response than B cells or splenocytes and prominently induced the expression of B7-1 and B7-2. Immunization with antigen-pulsed macrophages provided better recall responses compared to B cells. This was manifested by the high LFA-1alpha and low CD45RB expression on T cells. Because it is already known that mitomycin C-treated cells undergo apoptosis and dendritic cells engulf apoptotic cells, we therefore propose that generation of T cell response using antigen-pulsed allogeneic cells may be due to the engulfment of these cells by dendritic cells, which may then process and present antigen entrapped in allogeneic cells to activate naive CD(4+) T cells and differentiate them to Th1 cells. This study therefore provides a rational basis for manipulating antigen-specific responses by immunizing with antigen-pulsed allogeneic cells.

P-selectin and P-selectin glycoprotein ligand 1 are major determinants for Th1 cell recruitment to nonlymphoid effector sites in the intestinal lamina propria

The recruitment of activated T cell subsets to sites of effector immune responses is mediated by homing receptors induced upon activation in secondary lymphoid tissue. Using an adoptive transfer model, the intestinal recruitment of CD4+ T cells activated with intraperitoneal antigen in complete Freund's adjuvant was examined. The data demonstrate that activated CD4+ T cells recruited to intestinal Peyer's patches (PP) and lamina propria (LP) up-regulate functional P-selectin glycoprotein ligand 1 (PSGL-1). Blockade of IL-12 inhibited functional PSGL-1 expression and reduced PP and LP CD4+ T cell recruitment by >40%. P-selectin blockade reduced LP recruitment of activated cells by 56% without affecting PP recruitment. Studies of mice examined 3 d after adoptive transfer of differentiated T cell subsets revealed that Th1 but not Th2 cells were recruited to small intestine PP and LP. Mucosal addressin cell adhesion molecule blockade reduced Th1 recruitment to PP by 90% and to LP by >72%, whereas P-selectin blockade reduced Th1 recruitment to PP by 18% and Th1 recruitment to LP by 84%. These data suggest that IL-12-induced functional PSGL-1 expression is a major determinant for the recruitment of Th1 effector cells to noninflamed as well as inflamed intestine.

OX40 (CD134) controls memory T helper 2 cells that drive lung inflammation

Asthma is caused by memory Th2 cells that often arise early in life and persist after repeated encounters with allergen. Although much is known regarding how Th2 cells develop, there is little information about the molecules that regulate memory Th2 cells after they have formed. Here we show that the costimulatory molecule OX40 is expressed on memory CD4 cells. In already sensitized animals, blocking OX40-OX40L interactions at the time of inhalation of aerosolized antigen suppressed memory effector accumulation in lung draining lymph nodes and lung, and prevented eosinophilia, airway hyperreactivity, mucus secretion, and Th2 cyto-kine production. Demonstrating that OX40 signals directly regulate memory T cells, antigen-experienced OX40-deficient T cells were found to divide initially but could not survive and accumulate in large numbers after antigen rechallenge. Thus, OX40-OX40L interactions are pivotal to the efficiency of recall responses regulated by memory Th2 cells.

CCR4 is an up-regulated chemokine receptor of peripheral blood memory CD4+ T cells in Crohn's disease

Several chemokine receptors are expressed selectively on the surface of T cells depending on their polarization. The aim of this study was to characterize chemokine receptor expression in peripheral blood memory T cells in Crohn's disease (CD) and ulcerative colitis (UC), and to correlate the expression with disease activity. Peripheral blood mononuclear cells (PBMCs) were obtained from 24 patients with CD, 30 patients with UC, 24 normal controls and 10 disease controls. PBMCs were stained by anti-CCR3, CCR4, CCR5, CXCR3, CD4, CD8, CD45RO and beta 7 integrin, and the expression of the chemokine receptors were determined by flow cytometry. CCR4 expression on memory T cells was significantly lower in UC than in CD or normal controls, and that of memory CD4+ T and beta 7(high) memory CD4+ T cells was significantly higher in CD than in UC or normal controls. CCR4 expression on memory CD4+ T cells exhibited significant positive correlation with disease activity in CD, and this decreased significantly after treatment. Such a decrease was not found in the disease controls. CCR5 and CXCR3 expression on memory CD8+ T cells was significantly lower in CD than in normal controls. CXCR3 expression on beta 7(high) memory CD4+ T and CXCR3 expression on memory CD8+ T cells were lower in UC than in normal controls. These findings suggest that in peripheral blood memory T cells, chemokine receptor expression is different between CD and UC. Enhancement of CCR4 and suppression of CCR5 and CXCR3 seem to be the characteristic chemokine receptor profile in peripheral blood memory T cells of CD.

Effector CD8+CD45RO-CD27-T cells have signalling defects in patients with squamous cell carcinoma of the head and neck

A subset of circulating T cells (CD8(+)CD45RO(-)CD27(-)) with a naïve phenotype, but mediating effector function, is considered to play an important role in host antitumour defence. To investigate the attributes of these effector T cells in patients with squamous cell carcinoma (SCC) of the head and neck cancer, venous blood was obtained from 39 individuals with cancer and 45 normal controls (NC). Peripheral blood mononuclear cells were isolated, stained with labelled monoclonal antibodies specific for CD8, CD45RO, CD45RA, CD62L, CD27, TCR-zeta as well as isotype controls and examined by multicolour flow cytometry. Annexin V binding to CD8(+) T cells and PMA/ionomycin-induced IFN-gamma expression were also evaluated in patients and NC. The proportions of CD45RA(+)CD45RO(-) (naïve) and CD45RA(-)CD45RO(+) (memory) cells were found to be comparable within the CD8(+) T-cell subset. However, relative to NC, the frequency of effector CD8(+)CD45RO(-)CD27(-) cells was strikingly increased in all SCC patients regardless of the disease status (P=0.0003). The proportion of these cells was found to increase with age in both patients and NC. In NC, stimulated IFN-gamma expression was largely restricted to CD8(+)CD45RO(-)CD27(+) cells, while in patients CD8(+)CD45RO(-)CD27(-) expressed IFN-gamma after ex vivo stimulation. Expression of the TCR-associated zeta chain was decreased or absent in freshly isolated CD8(+)CD45RO(-)CD27(-) T cells in patients (P<0.0001). Annexin V was found to bind to a higher proportion of circulating CD8(+) T cells in patients than NC (P<0.006), and significantly more Annexin V(+) T cells were present in the effector (P<0.0059) than the naïve subset within the CD8(+)CD45RO(-) compartment. The data indicate that the expanded CD8(+)CD45RO(-)CD27(-) T cells, which contain precursors of IFN-gamma-producing T cells, are zeta-negative and sensitive to apoptosis in the circulation of patients with HNC.

Decreased effector memory CD45RA+ CD62L- CD8+ T cells and increased central memory CD45RA- CD62L+ CD8+ T cells in peripheral blood of rheumatoid arthritis patients

Although a role for CD8+ T cells in the pathogenesis of rheumatoid arthritis (RA) has been suggested, the precise nature of their involvement is not fully understood. In the present study we examined the central and effector memory phenotypes of CD4+ and CD8+ T cells in the peripheral blood of patients with RA and systemic lupus erythematosus. Terminally differentiated effector memory CD45RA+CD62L-CD8+ T cells were significantly decreased in RA patients, whereas the central memory CD45RA-CD62L+ CD8+ T-cell population was increased as compared with levels in healthy control individuals. Naïve and preterminally differentiated effector memory CD45RA-CD62L- CD8+ T cells did not differ between RA patients and control individuals. The CD45RA-CD62L+ central memory CD4+ T-cell subpopulation was increased in RA patients, whereas the naïve and effector memory phenotype of CD4+ T cells did not differ between RA patients and control individuals. In patients with systemic lupus erythematosus the distribution of naïve/memory CD4+ and CD8+ T cells did not differ from that in age- and sex-matched control individuals. These findings show that peripheral blood CD8+ T cells from RA patients exhibit a skewed maturation phenotype that suggests a perturbation in the homeostasis of these cells. The central memory CD45RA-CD62L+ CD4+ and CD8+ T-cell numbers were increased in RA, suggesting an accelerated maturation of naïve T cells. The decreased numbers of terminally differentiated CD45RA+CD62L- effector memory CD8+ T cells in peripheral blood of RA patients may reflect increased apoptosis of these cells or enhanced migration of these cells to sites of inflammation, which may play a role in the pathogenesis of RA.

Homeostasis-stimulated proliferation drives naive T cells to differentiate directly into memory T cells

The developmental requirements for immunological memory, a central feature of adaptive immune responses, is largely obscure. We show that as naive CD8 T cells undergo homeostasis-driven proliferation in lymphopenic mice in the absence of overt antigenic stimulation, they progressively acquire phenotypic and functional characteristics of antigen-induced memory CD8 T cells. Thus, the homeostasis-induced memory CD8 T cells express typical memory cell markers, lyse target cells directly in vitro and in vivo, respond to lower doses of antigen than naive cells, and secrete interferon gamma faster upon restimulation. Like antigen-induced memory T cell differentiation, the homeostasis-driven process requires T cell proliferation and, initially, the presence of appropriate restricting major histocompatibility complexes, but it differs by occurring without effector cell formation and without requiring interleukin 2 or costimulation via CD28. These findings define repetitive cell division plus T cell receptor ligation as the basic requirements for naive to memory T cell differentiation.

Differentiating between memory and effector CD8 T cells by altered expression of cell surface O-glycans

Currently there are few reliable cell surface markers that can clearly discriminate effector from memory T cells. To determine if there are changes in O-glycosylation between these two cell types, we analyzed virus-specific CD8 T cells at various time points after lymphocytic choriomeningitis virus infection of mice. Antigen-specific CD8 T cells were identified using major histocompatibility complex class I tetramers, and glycosylation changes were monitored with a monoclonal antibody (1B11) that recognizes O-glycans on mucin-type glycoproteins. We observed a striking upregulation of a specific cell surface O-glycan epitope on virus-specific CD8 T cells during the effector phase of the primary cytotoxic T lymphocyte (CTL) response. This upregulation showed a strong correlation with the acquisition of effector function and was downregulated on memory CD8 T cells. Upon reinfection, there was again increased expression of this specific O-glycan epitope on secondary CTL effectors, followed once more by decreased expression on memory cells. Thus, this study identifies a new cell surface marker to distinguish between effector and memory CD8 T cells. This marker can be used to isolate pure populations of effector CTLs and also to determine the proportion of memory CD8 T cells that are recruited into the secondary response upon reencounter with antigen. This latter information will be of value in optimizing immunization strategies for boosting CD8 T cell responses.

Differential roles of interleukin 15 mRNA isoforms generated by alternative splicing in immune responses in vivo

At least two types of interleukin (IL)-15 mRNA isoforms are generated by alternative splicing at the 5' upstream of exon 5 in mice. To elucidate the potential roles of IL-15 isoforms in immune responses in vivo, we constructed two groups of transgenic mice using originally described IL-15 cDNA with a normal exon 5 (normal IL-15 transgenic [Tg] mice) and IL-15 cDNA with an alternative exon 5 (alternative IL-15 Tg mice) under the control of an MHC class I promoter. Normal IL-15 Tg mice constitutionally produced a significant level of IL-15 protein and had markedly increased numbers of memory type (CD44(high) Ly6C(+)) of CD8(+) T cells in the LN. These mice showed resistance to Salmonella infection accompanied by the enhanced interferon (IFN)-gamma production, but depletion of CD8(+) T cells exaggerated the bacterial growth, suggesting that the IL-15-dependent CD8(+) T cells with a memory phenotype may serve to protect against Salmonella infection in normal IL-15 Tg mice. On the other hand, a large amount of intracellular IL-15 protein was detected but hardly secreted extracellularly in alternative IL-15 Tg mice. Although most of the T cells developed normally in the alternative IL-15 Tg mice, they showed impaired IFN-gamma production upon TCR engagement. The alternative IL-15 transgenic mice were susceptible to Salmonella accompanied by impaired production of endogenous IL-15 and IFN-gamma. Thus, two groups of IL-15 Tg mice may provide information concerning the different roles of IL-15 isoforms in the immune system in vivo.

Protective heterologous antiviral immunity and enhanced immunopathogenesis mediated by memory T cell populations

A basic principle of immunology is that prior immunity results in complete protection against a homologous agent. In this study, we show that memory T cells specific to unrelated viruses may alter the host's primary immune response to a second virus. Studies with a panel of heterologous viruses, including lymphocytic choriomeningitis (LCMV), Pichinde (PV), vaccinia (VV), and murine cytomegalo (MCMV) viruses showed that prior immunity with one of these viruses in many cases enhanced clearance of a second unrelated virus early in infection. Such protective immunity was common, but it depended on the virus sequence and was not necessarily reciprocal. Cell transfer studies showed that both CD4 and CD8 T cell populations from LCMV-immune mice were required to transfer protective immunity to naive hosts challenged with PV or VV. In the case of LCMV-immune versus naive mice challenged with VV, there was an enhanced early recruitment of memory phenotype interferon (IFN) gamma-secreting CD4(+) and CD8(+) cells into the peritoneal cavity and increased IFN-gamma levels in this initial site of virus replication. Studies with IFN-gamma receptor knockout mice confirmed a role for IFN-gamma in mediating the protective effect by LCMV-immune T cell populations when mice were challenged with VV but not PV. In some virus sequences memory cell populations, although clearing the challenge virus more rapidly, elicited enhanced IFN-gamma-dependent immunopathogenesis in the form of acute fatty necrosis. These results indicate that how a host responds to an infectious agent is a function of its history of previous infections and their influence on the memory T cell pool.

Phenotypic characterization of T cells in bronchoalveolar lavage fluid (BALF) and peripheral blood of patients with diffuse panbronchiolitis; the importance of cytotoxic T cells

We investigated the contribution of T cells in diffuse panbronchiolitis (DPB) by identifying T cell subsets in BALF of 36 patients with DPB, before and after long-term treatment with macrolide antibiotics, and 16 healthy control subjects. The percentages of lymphocytes and CD3+ gammadelta+ cells in BALF of DPB patients and control subjects were similar, but the absolute number of these cells was higher in DPB patients. Treatment resulted in a significant reduction in the absolute number of these cells. A further two-colour analysis of T cell subsets in BALF showed a significantly higher ratio and number of CD8+ HLA-DR+ cells in DPB patients. Treatment resulted in a significant reduction of activated T cells. Most BALF CD8+ cells were CD8+ CD11b- cytotoxic T cells. The number of these cells in BALF of DPB patients (26.69 +/- 5.86 x 10(3)/ml) was higher than the control (2.02 +/- 0.38 x 10(3)/ml; P < 0.001), and a significant reduction was observed after treatment (7.69 +/- 2.59 x 10(3)/ml; P < 0.01). The number of CD4+ cells was also higher in DPB patients than in controls, and most were CD4+ CD29+ memory T cells. However, treatment did not influence the number of these cells. The number of lymphocytes, CD3+ gammadelta+, CD8+ CD11b-, CD8+ HLA-DR+, and CD4+ CD29+ cells was higher in patients with bacterial infection than in those without bacterial infection, and interestingly, macrolide therapy reduced the number of lymphocytes, CD3+ gammadelta+, CD8+ CD11b- and CD8+ HLA-DR+ cells, irrespective of bacterial infection. In peripheral blood, the percentage of CD8+ HLA-DR+ cells was also higher in DPB patients than in healthy subjects, and significantly decreased after treatment. The percentage of CD8+ CD11b- cells in peripheral blood was similar in DPB patients and normal subjects, and treatment significantly reduced the percentage of these cells. Finally, the expression of the adhesion molecules CD11a/CD18 (alpha/beta-chains of LFA-1) on lung CD3+ cells and CD49d (alpha-chain of VLA) on lung CD4+ cells was enhanced compared with that on peripheral blood in DPB patients. Our results suggest that elevation of memory T cells and activation of CD8+ cells, mainly cytotoxic T cells, in the airway lumen of DPB patients may contribute to chronic bronchial inflammation, possibly through up-regulation of adhesion molecules. Our findings also indicate that macrolide antibiotics may have a direct or indirect suppressive effect on cytotoxic T cells, and as such, reduce inflammation and improve clinical condition.