CD4+CD25+ immunoregulatory T cells may not be involved in controlling autoimmune arthritis

Accumulating evidence suggests that regulatory T cells play a crucial role in preventing autoimmunity. Recently, a naturally occurring CD4+CD25+ T-cell subset that is anergic and also suppressive has been shown to suppress autoimmunity in several animal models. We used proteoglycan-induced arthritis (PGIA) as a study model to investigate the role of the CD4+CD25+ regulatory T cells in autoimmune arthritis. There was no significant change in the percentage of CD4+CD25+ T cells during the immunization period when proteoglycan- or ovalbumin-immunized BALB/c and C57BL/6 mice were compared. An adoptive transfer study showed that the CD4+CD25+ T cells did not protect severe combined immunodeficient mice from arthritis when they were cotransferred with splenocytes from arthritic animals. Similarly, depletion of the CD4+CD25+ T cells did not enhance the onset of the disease or disease severity in severe combined immunodeficient mice. Moreover, CD28-deficient mice, which have very few CD4+CD25+ T cells, were highly resistant to PGIA. These findings indicate that the CD4+CD25+ regulatory T cells may not play a critical role in controlling PGIA.

Characterizing immune reconstitution after long-term highly active antiretroviral therapy in pediatric AIDS

In this study, we sought to characterize the T lymphocyte recovery in vertically HIV-1-infected children who respond to long-term highly active antiretroviral therapy (HAART). A 3-year longitudinal retrospective study was used to perform a cross-sectional study of 32 children rated according to the time course of CD4(+) T cell percentages in response to antiretroviral therapy and CDC clinical classification: (1) long-term asymptomatic (LTA group): 8 children in A1 during the whole follow-up period; (2) responsive to HAART (Rec group): 13 children in C3 before HAART who achieved CD4(+) T cell counts of > 500 cells/mm(3) after 3 years of HAART; and (3) nonresponsive to HAART (Non-Rec group): 11 children in C3 during the whole follow-up period despite 3 years of HAART. We also studied 17 healthy age-matched uninfected children as controls. Lymphoproliferative responses (LPRs) were evaluated by incorporation of [(3)H]thymidine, identification of T cell subsets by three-color flow cytometry, and determination of thymic production of T cells by quantification of T cell receptor rearrangement excision circles (TRECs). Interestingly, the Rec group showed an increase in percentage of CD4(+) T cells and a decrease in viral load, and recovered LPRs to mitogens and recall antigens, with values similar to those of the LTA group. Moreover, the Rec group produced similar percentages and absolute counts of naive (CD45RA(+)CD62L(+)) CD4(+) and CD8(+) T cells, and TRECs similar to those of the LTA group. In particular, the Rec group produced similar percentages of CD8(+)CD28(-)CD57(+) and CD8(+)CD28(-)CD57(-) T cell subsets compared with controls. Our data indicate that among children who have already progressed to AIDS and severe immunodeficiency but who respond to HAART, the immune system can recover and resemble those of nonprogressors or even uninfected children, in quantitative as well as in functional terms.

Interferon-gamma-secreting T cells localize to the epithelium in coeliac disease

Increased levels of interferon-gamma (IFN-gamma) transcripts have previously been found in duodenal biopsy specimens from patients with untreated coeliac disease (CD). Such samples and duodenal control mucosa were therefore studied to locate and phenotype cells spontaneously secreting IFN-gamma. Specimens were collected from consecutively recruited patients with untreated (seven), treated (four) or refractory (three) CD and from five histologically normal controls. Morphological and immunohistochemical examinations were performed, and epithelial and lamina propria cell suspensions were prepared from parallel samples. Unstimulated viable cells secreting IFN-gamma were identified and phenotyped with a new fluorescence-activated cell sorter-based assay, and IFN-gamma messenger RNA (mRNA) was analysed in snap-frozen aliquots of the same suspensions. Untreated CD cases had the highest fraction of IFN-gamma+ cells in the epithelial compartment (median 2.6%, range 1.6-6.2%) and, less strikingly, in the lamina propria compartment (1.6%, range 0.3-3.6%), followed by refractory (1.4%, 1.0-1.9%; and 0.3%, 0.0-1.2%) and treated (0.8%, 0.5-0.9%; and 0.7%, 0.2-1.1%) disease and finally the controls (0.5%, 0.3-0.9%; and 0.2%, 0.1-0.7%). IFN-gamma mRNA data supported these findings. IFN-gamma+ intraepithelial lymphocytes were mostly CD3+ and CD8+, whereas many positive lamina propria cells were CD8-. We conclude that isolated T cells spontaneously secreting IFN-gamma localize preferentially in the epithelium of patients with classical and refractory CD.

Nasal administration of CTB-insulin induces active tolerance against autoimmune diabetes in non-obese diabetic (NOD) mice

Nasal administration of beta cell-derived auto-antigens has been reported to suppress the development of autoimmune diabetes. We investigated the tolerogenic effects of insulin conjugated to the B subunit of cholera toxin (CTB). Nasal administration of 1 micro g of CTB-insulin significantly delayed the incidence of diabetes in comparison to CTB treated mice. However, administration of 4 or 8 micro g of the conjugate had no protective effect. Protection induced by CTB-insulin was transferred to naive recipients by splenic CD4+ T cells. This result favours an active cellular mechanism of regulation, which was lost using higher (4-8 micro g) or lower (0.1-0.5 micro g) amounts of the conjugate. When co-administered with diabetogenic T cells, splenic T cells from CTB-insulin-treated mice reduced the lymphocytic infiltration of the islets. Reverse transcription-polymerase chain reaction analysis of recipients' pancreatic glands revealed an increase of TGF-beta and IL-10 transcripts after donor mice tolerization, while levels of IFN-gamma and IL-4 RNAs were unchanged. We observed a significant increase of T cell proliferation after unspecific stimulation in the spleen and pancreatic lymph nodes 24 h after CTB-insulin administration in -comparison to control treatment. Higher amounts of IL-4 and IFN-gamma were noticed in pancreatic lymph nodes of tolerized mice upon in vitro stimulation. Antigen-specific unresponsiveness after immunization and upon subsequent in vitro exposure to homologous antigen was obtained in nasally treated animals. Our results underlined the importance of nasal mucosa as an inducing site of tolerance and provided evidence for similar mechanisms of action to what has been described for the oral route, which favoured a CTB-insulin specific effect.

Acute P. falciparum malaria induces a loss of CD28- T IFN-gamma producing cells

P. falciparum malaria is associated with increased activation among peripheral lymphocytes. In the present study, we investigated markers of susceptibility to apoptosis and expression of IFN-gamma and IL-4 by CD28-and CD28+T cells in West African children with acute P. falciparum malaria. The study showed increased susceptibility to apoptosis and cytokine production among T lymphocytes during acute malaria but also that T cells, in particular IFN-gamma producing CD28-T cells, were substantially reduced. These results are in line with previous studies suggesting that certain T cell subsets are sequestered away from the peripheral blood during P. falciparum malaria.

Heterogeneity of CD4 and CD8+ memory T cells in localized and generalized Wegener's granulomatosis

Memory T cells display phenotypic heterogeneity. Surface antigens previously regarded as exclusive markers of naive T cells, such as L-selectin (CD62L), can also be detected on some memory T cells. Moreover, a fraction of CD45RO+ (positive for the short human isoform of CD45) memory T cells reverts to the CD45RA+ (positive for the long human isoform of CD45) phenotype. We analyzed patients with biopsy-proven localized Wegener's granulomatosis (WG) (n = 5), generalized WG (n = 16) and age- and sex-matched healthy controls (n = 13) to further characterize memory T cells in WG. The cell-surface expression of CD45RO, CD45RA, CD62L, CCR3, CCR5 and CXCR3 was determined on blood-derived T cells by four-color flow cytometric analysis. The fractions of CCR5+ and CCR3+ cells within the CD4+CD45RO+ and CD8+CD45RO+ memory T cell populations were significantly expanded in localized and generalized WG. The mean percentage of Th1-type CCR5 expression was higher in localized WG. Upregulated CCR5 and CCR3 expression could also be detected on a fraction of CD45RA+ T cells. CD62L expression was seen on approximately half of the memory T cell populations expressing chemokine receptors. This study demonstrates for the first time that expression of the inducible inflammatory chemokine receptors CCR5 and CCR3 on CD45RO+ memory T cells, as well as on CD45RA+ T cells ('revertants'), contributes to phenotypic heterogeneity in an autoimmune disease, namely WG. Upregulated CCR5 and CCR3 expression suggests that the cells belong to the effector memory T cell population. CCR5 and CCR3 expression on CD4+ and CD8+ memory T cells indicates a potential to respond to chemotactic gradients and might be important in T cell migration contributing to granuloma formation and vasculitis in WG.

Stage-specific changes in fetal thymocyte proliferation during the CD4-8- to CD4+8+ transition in wild type, Rag1-/-, and Hoxa3,Pax1 mutant mice

BACKGROUND

The function of the thymic microenvironment is to promote thymocyte maturation, in part via regulation of thymocyte proliferation and cell death. Defects in fetal thymic epithelial cell (TEC) development and function, and therefore in the formation of a functional microenvironment, can be caused either directly by TEC differentiation defects or indirectly by defective thymocyte maturation. In this paper we studied fetal thymocyte proliferation during the early transition from the CD3-4-8- (triple negative, TN) to CD4+8+ (double positive, DP) stages. We compared wild type mice with Rag1-/- mice and with Hoxa3+/-Pax1-/- compound mutant mice, which have blocks at different stages of thymocyte development.

RESULTS

Wild type fetal and adult thymus showed stage-specific differences in the proliferation profiles of developing thymocytes, with fetal stages showing generally higher levels of proliferation. The proliferation profile of fetal thymocytes from Rag1-/- mutants also had stage-specific increases in proliferation compared to wild type fetal thymocytes, in contrast to the lower proliferation previously reported for thymocytes from adult Rag1-/- mutants. We have previously shown that Hoxa3+/-Pax1-/- mice have abnormal fetal TEC development, resulting in increased apoptosis at the TN to DP transition and decreased DP cell numbers. Fetal thymocytes from Hoxa3+/-Pax1-/- compound mutants had increased proliferation, but fewer proliferating cells, at the DP stage. We also observed a decrease in the level of the cytokines IL-7 and SCF produced by Hoxa3+/-Pax1-/-TECs.

CONCLUSION

Our results indicate complex and stage-specific effects of abnormal TEC development on thymocyte proliferation.

Expression of the integrin alpha Ebeta 7 identifies unique subsets of CD25+ as well as CD25- regulatory T cells

Regulatory CD25(+)CD4(+) T cells are considered as important players in T cell homeostasis and self-tolerance. Here we report that the integrin alpha(E)beta(7), which recognizes epithelial cadherin, identifies the most potent subpopulation of regulatory CD25(+) T cells. Strikingly, CD25-negative alpha(E)+CD4(+) T cells displayed regulatory activity. Both alpha(E)+ subsets, CD25(+) and CD25(-), express CTLA-4, suppress T cell proliferation in vitro, and protect mice from colitis in the severe combined immunodeficient model (SCID) in vivo. Whereas alpha(E)+CD25(+) T cells produce almost no cytokines, alpha(E)+CD25(-) T cells represent a unique subset in which high IL-2, IFN-gamma and T helper 2-cytokine production is linked with suppressive function. Thus, the integrin alpha(E)beta(7) can be regarded as a novel marker for subsets of highly potent, functionally distinct regulatory T cells specialized for crosstalk with epithelial environments.

Flow cytometric quantitation and characterization of the T-lymphocyte memory response to CMV in healthy donors

BACKGROUND

Levels of circulating CMV Ag-specific lymphocytes determine CMV reactivation risk in immunocompromised individuals.

METHODS

Frequencies of T cells producing cytokines after stimulation by CMV Ag were measured in hematopoietic stem-cell donors using flow cytometry.

RESULTS

In seropositive individuals (n = 75) the mean number of CD8(+) (CD8(bright), CD8(dim)) and CD4(+) cells producing IFN-gamma was respectively 3.1% (12.6/microL) and 0.38% (3.2/microL), over 10-fold higher than in seronegative subjects (n = 22). CMV stimulation induced tumor necrosis factor-alpha (TNF-alpha) and interferon-gamma (IFN-gamma) in both CD4(+) and CD8(+) cells (usually together), with a shift from memory- to effector-cell phenotype, while only a small proportion of CD4(+) cells produced IL-4. Although the normal range was wide, neither age, sex nor HLA type affected the frequency.

DISCUSSION

These quantitative studies and the recognition of CD4(+) cells as potential effectors of CMV immunity are of relevance for immunotherapeutic approaches to prevent CMV disease after stem-cell transplantation.

Activated T cells in the surface secretion on the adenoid--a flow cytometric study

We previously demonstrated the presence of leucocytes in the adenoid surface secretion with the ability of immunoglobulin A (IgA), IgM and IgG production as well as production of cells with phagocytic capacity. In the present study, we investigated the presence of activated T cells in the secretion. Adenoid surface secretion from 12 children subjected to adenoidectomy was obtained with an imprint method. From six children, peripheral blood was also obtained. By flow cytometry, the number of lymphocytes, granulocytes, epithelial cells and red blood cells was analysed as well as the expression on lymphocyte subsets of the following antigens: CD3, CD4, CD8, CD19, CD25, CD38, CD45RO, CD45RA, HLA-DR, TcRgd, CD161 and l-selectin. The majority of T cells were activated and to a significantly higher degree were CD45RO+, CD161+ and l-selectin-, as compared with the corresponding peripheral blood. The median percentage of B cells and T cells in the secretion were 81 and 13%, respectively. In conclusion, the proportion of B and T cells in the adenoid surface secretion is significantly different as compared with the peripheral blood. The T cells in the adenoid surface secretion are to a high degree activated. The results suggest that the leucocytes in the surface secretion are part of the mucosal defence.

The study of T-cell activation in peripheral blood and spleen of hepatosplenic patients suggests an exchange of cells between these two compartments in advanced human Schistosomiasis mansoni infection

A histopathological and immunophenotypic study was performed on the spleen of patients with hepatosplenic (HS) schistosomiasis mansoni. Morphological data demonstrated that all HS patients presented features related to Schistosoma mansoni-induced splenomegaly, such as red pulp congestion and atrophy/hyperplasia of white pulp. The morphological diversity of the white pulp seems to be associated with the expansion of activated CD4+ T-cell subpopulation. The data obtained suggest that the spleen is an important site for T-cell activation during severe chronic infection with S. mansoni. In addition, we have compared the cell populations/subpopulations presented in the peripheral blood with that observed in the spleen of patients with HS schistosomiasis mansoni. We observed a significant increase in the percentage of activated CD4+HLA-DR+ and CD8+HLA-DR+ T cells in both the spleen and the peripheral blood of HS patients in comparison with noninfected individuals (NOR). These data suggest an exchange of cells between these two compartments. However, we observed normal expression of the CD28 molecule by CD8+ T cells in the spleen, despite a lower percentage of these cells in the peripheral blood. This finding supports the hypothesis that the decrease in CD28 expression, by CD8+ cells, is an event that takes place outside the spleen during human schistosomiasis infection. The most important conclusion is the fact that the analysis of T-cell activation in the peripheral blood reflects the major immunological reactivity that occurs in the spleen during human schistosomiasis and that the morphological aspects of the spleen may reflect the functional activity of T cells. The specificities of T cells and the roles they may play in the pathogenesis during chronic schistosomiasis now need to be determined.

Immune reconstitution

Immune reconstitution in HIV-infected patients remains a potential mechanism to explain delayed disease progression and increased survival following suppressive therapy. Many discrepancies remain to be studied. Is an immune response to HIV protective? Why are anti-HIV CD4 responses lost so quickly in progressors and how can they be restored? What is the damage to the immune system that occurs early in disease and why can it not be overcome by simply controlling viral replication? Will management of immune reconstitution be used in future adjunct treatment strategies (vaccine or STI)? Because HAART is not the answer to long-term management of HIV throughout the world, the recovery of immune function and it's potential to control viral replication remains a key goal in the long-term management of HIV-infected persons.

Activation of pulmonary T cells in corticosteroid-resistant and -sensitive interstitial pneumonitis in dermatomyositis/polymyositis

To study the activation states and cytokine profiles of pulmonary T cells in corticosteroid-resistant and corticosteroid-sensitive interstitial pneumonitis (IP) in dermatomyositis (DM)/polymyositis (PM), we examined the activation markers and cytokine profiles of T cells in bronchoalveolar lavage fluids (BALF) from patients with IP in DM/PM before prednisolone therapy and then compared the activation states of T cells according to the therapeutic response of IP to prednisolone therapy. CD25+ CD4+ T cells in BALF were significantly increased in both corticosteroid-resistant and corticosteroid-sensitive IP in DM/PM as compared with those in controls without IP. Furthermore, CD25+ CD4+ T cells in BALF were significantly more increased in corticosteroid-resistant IP than those in cortico teroid- sensitive IP. Moreover, CD25+ CD8+ T cells in BALF were significantly increased only in corticosteroid-resistant IP, but not in corticosteroid-sensitive IP or controls without IP. IFN-gamma mRNA was detected in BALF T cells in corticosteroid-resistant and corticosteroid-sensitive IP but not in controls without IP, whereas IL-4 mRNA was virtually undetected in BALF T cells in both the IP groups. However, there were no significant differences in CD4/CD8 ratio of BALF T cells, HLA-DR+ BALF T cells or CD25+ and HLA-DR+ peripheral blood T cells between the two IP groups. These results indicate that activated Th1-type pulmonary T cells play an important role in the development of corticosteroid- resistant IP in DM/PM and that the increase in CD25+ CD8+ T cells in BALF is a useful indicator for corticosteroid-resistant IP in DM/PM and hence may be an indicator for early use of cyclosporin.

Temporary restoration of immune response against Toxoplasma gondii in HIV-infected individuals after HAART, as studied in the hu-PBMC-SCID mouse model

We studied immune reconstitution against the parasite T. gondii in HIV-infected patients treated for 1 years with highly active antiretroviral therapy (HAART). We used SCID mice, humanized with peripheral blood mononuclear cells (PBMC) from patients, which were then infected with T. gondii cysts. Mice humanized with PBMC from patients before the start of HAART were highly susceptible to infection. In contrast, mice humanized with PBMC from patients who had received HAART for 6 months displayed higher survival rates, correlating with lower intracerebral parasite loads. However, this resistance was lost during follow up because mice humanized with PBMC from patients treated with HAART for 12 months survived for no longer than mice that had not been humanized. Specific lymphocyte proliferation assays showed that the increase in proliferative response depended on treatment duration and that HAART induced changes in IFN-gamma secretion in the presence of Toxoplasma antigens. Thus, our results indicate partial immune reconstitution against T. gondii in HIV-infected patients following HAART, possibly due to changes in the patterns of specific IFN-gamma production and redistribution of functional memory CD4+ cells.

A composite picture of TcR alpha/beta(+) CD4(-)CD8(-) T Cells (alpha/beta-DNTCs) in humans with autoimmune lymphoproliferative syndrome

The discovery of an unusual T-cell subset characterized by the expression of the alpha/beta T-cell receptor without expression of either CD4 or CD8 [alpha/beta-double-negative T cells (alpha/beta-DNTCs)] provided critical insights in the evaluation of a "new" lymphoproliferative disorder known as autoimmune lymphoproliferative syndrome (ALPS). ALPS is a disorder of defective Fas-mediated lymphocyte apoptosis, manifested by accumulation of alpha/beta-DNTCs and other lymphocyte subsets, leading to lymphadenopathy and splenomegaly, autoimmunity, and an increased risk of lymphoma. The expanded population of alpha/beta-DNTCs from ALPS patients has a remarkable uniform phenotype that is for the most part similar to alpha/beta-DNTCs from mice with defective Fas (lpr) or Fas ligand (gld). This is in contrast to the minor alpha/beta-DNTC compartment in healthy individuals that contains multiple, immunophenotypically distinct subpopulations. Current data indicate that alpha/beta-DNTCs from ALPS patients are derived from cytotoxic CD8(+) T cells, chronically activated in vivo but anergic in vitro. Their anergic state may be related to persistent modifications of O-linked carbohydrates on cell surface molecules, such as CD43 and CD45, as well as to the increased presence of interleukin-10. Although largely consistent with a model of (linear) CD8(+) cytotoxic T-cell differentiation, the expression patterns of certain surface molecules, such as CD27 and CD28, are not consistent with this model. This may be the result of the perturbed homeostasis of lymphocytes in ALPS, thereby revealing pathways of differentiation and immunophenotypes, including phenotypes pertaining to cell surface glycosylation that are hidden from view in healthy individuals.

A unique subset of self-specific intraintestinal T cells maintains gut integrity

Lymphocytes residing in the intestinal epithelium are exclusively T cells and account for one of the largest collection of T cells in the organism. However, their function remains obscure. We and others have shown that the development of intestinal intraepithelial T cells is compromised in mutant mice prone to chronic intestinal inflammation. These results led us to directly assess their role in regulating the development of colitis secondary to transfer of primary splenic TCRalphabeta(+)CD4(+)CD45RB(hi) T cells into severe combined immunodeficiency (SCID) mice. Here we demonstrate that prior reconstitution of SCID recipients with intraintestinal TCRalphabeta(+)CD4(-)CD8alpha(+)beta(-) T cells prevents disease, and does so in an interleukin (IL)-10-dependent fashion. In contrast, reconstitution with either TCRgammadelta(+) or TCRalphabeta(+)CD4(-) CD8alpha(+)beta(+) intestinal T cells did not prevent colitis. TCRalphabeta(+)CD4(-)8alpha(+)beta(-) T cells are unique to the intestinal epithelium of both rodents and humans. Previous repertoire analyses of TCRalphabeta(+)CD4(-)CD8alpha(+)beta(-) T cells revealed a high proportion of cells expressing high affinity, self-specific TCR within this subset. We demonstrate that monoclonal, self specific TCRalphabeta(+)CD4(-)CD8alpha(+)beta(-) cells derived from TCR transgenic mice also prevent the onset of colitis. Thus, intestinal TCRalphabeta(+)CD4(-)CD8alpha(+)beta(-) T cells, selected based on their self-reactivity, maintain gut integrity in a IL-10-dependent fashion.

Heterogeneity of the DN4 (CD44-CD25-) subset of CD4-CD8- double negative thymocytes; dependence on CD3 signaling

Recent studies have shown that apoptotic cell death associated with selection for thymocytes that express clonotypic TCRbeta or TCRgammadelta proteins takes place in the DN4 (CD44-CD25-) subset of CD4-CD8- double negative (DN) thymocytes. A detailed analysis of the DN4 subset is therefore of interest. Using intracellular (IC) staining for clonotypic TCR and CD3varepsilon proteins we find that DN4 cells consist of five subpopulations: TCRbetaIC(high)/CD3varepsilonIC(high)/TCRgammadeltaIC-, TCRbetaI-C-/CD3varepsilonIC(high)/TCRgammadeltaIC(+), TCRbetaIC(high)/CD3varepsilonIC(high)/TCRgammadeltaIC(+), TCRbetaIC(low)/CD3varepsilonIC(low)/TCRgammadeltaIC(-), and TCRbetaIC(-)/CD3varepsilonIC(-)/TCRgammadeltaIC(-). Expression levels of IC TCRbeta/CD3varepsilon, and of Thy1.2, CD2, and CD69 at the cell surface suggest that the TCRbetaIC(low)/CD3varepsilonIC(low)/TCRgammadeltaIC(-) subset harbors the direct precursors of DP cells, and is critical for life/death decisions in early thymic selection. TCRbeta/CD3varepsilon downregulation is less pronounced in DN4 and DP cells of mice deficient for CD3zeta or for p56(lck), suggesting that the dynamics of TCR protein regulation in the DN4 subset is dependent on CD3 signaling.

Effect of dosage of anticancer agents during transcatheter arterial chemoembolization on T cell subsets in patients with hepatocellular carcinoma

OBJECTIVE

To investigate the effects of the dosage of anticancer agents during transcatheter arterial chemoembolization (TACE) on the T cell subsets in patients with hepatocellular carcinoma (HCC).

METHODS

Thirty-six patients with unresectable HCC were randomly divided into 2 groups to receive superselective TACE. Patients in group A (n=18) received low-dose (2-4 mg) mitomycin C (MMC) as the anticancer drug when the tumor was less than 5 cm in diameter; when the tumor ranged from 5 and 8 cm in diameter, 4-6 mg MMC along with 10 mg epirubicin (EPI) was given, and in cases of even larger tumors, 6-8 mg MMC, 10 mg EPI and 100 mg CBP were prescribed. Conventional chemotherapy regimen constituted by 10 mg MMC, 40 mg PI and 300 mg CBP was adopted in group B (n=18). The peripheral blood T cell subsets including CD3(+), CD4(+), CD8(+), NK, CD4(+)/CD8(+) ratio, CD4(+)CD45(+), CD4(+)CD29(+), CD8(+)CD28(+) and CD8(+)CD28- were measured by flow cytometry in both groups before and one week after treatment.

RESULTS

The T cell subsets were comparable in the 2 groups before the treatment. After TACE, no significant changes occurred in CD3(+), CD4(+), CD8(+), NK, CD4(+)/CD8(+), CD4(+)CD29(+) or CD8(+)CD28- cells in group A, while significant decrease in CD4(+)CD45(+) and increase in CD8(+)CD28(+) cells were observed (P<0.05 and P<0.001, respectively). In group B, CD4(+) and CD4(+)CD29(+) levels, together with CD4(+)/CD8(+) ratio, were significantly lower than those before treatment (P<0.05), but CD8(+) and CD8(+)CD28- subsets were significantly higher (P<0.05).

CONCLUSIONS

The cellular immune function of HCC patients is significantly impaired by anticancer drugs for TACE at conventional dose, while low-dose of the drugs may enhance the cellular immune function.

Syngeneic mixed lymphocyte reaction (SMLR) with dendritic cells: direct visualization of dividing T cell subsets in SMLR

Syngeneic mixed lymphocyte reaction (SMLR) has been considered to represent T cell response to self antigens. In this study using stimulator dendritic cells (DC), we analyzed cellular components responding to the syngeneic DC. It was shown that the predominant dividing cells were CD8(+) T cells although the response of CD4(+) T cells was essential for initiation of SMLR. In spite of the vigorous proliferation and expression of several activation markers, these SMLR-activated CD8(+) T cells hardly killed syngeneic targets and most of the CD8(+) T cells produced no interferon-gamma upon restimulation with DC. Furthermore, in SMLR where CD8(+) T cells were absent or inhibited, a considerable proliferation of CD4(-) CD8(-) double negative-T cells that included TCRalpha/beta(+) natural killer-T cells (NKT cells), TCRgamma/delta(+) NKT cells and TCRgamma/delta(+) T cells was observed.

BY55/CD160 acts as a co-receptor in TCR signal transduction of a human circulating cytotoxic effector T lymphocyte subset lacking CD28 expression

In the present study, we examined the role of the recently identified glycosylphosphatidylinositol (GPI)-anchored cell surface molecule BY55, assigned as CD160, in TCR signaling. CD160 is expressed by most intestinal intraepithelial lymphocytes and by a minor subset of circulating lymphocytes including NK, TCRgammadelta and cytotoxic effector CD8bright+CD28- T lymphocytes. We report that CD160, which has a broad specificity for MHC class Ia and Ib molecules, behaves as a co-receptor upon T cell activation. Anti-CD160 mAb enhance the CD3-induced proliferation of freshly isolated CD160-enriched peripheral blood lymphocytes and CD160+ T cell clones. Further, the engagement of CD160 receptors on normal clonal T lymphocyte populations lacking CD4, CD8 and CD28 molecules by MHC class I molecules results in an increased CD3-induced cell proliferation. Further, we found that CD160 co-precipitates with the protein tyrosine kinase p56lck and tyrosine phosphorylated zeta chains upon TCR-CD3 cell activation. Thus, we demonstrate that CD160 provides co-stimulatory signals leading to the expansion of a minor subset of circulating lymphocytes including double-negative CD4/CD8 T lymphocytes and CD8bright+ cytotoxic effector T lymphocytes lacking CD28 expression.

Variegated expression of CD8 alpha resulting from in situ deletion of regulatory sequences

The developmental and subset-specific expression of the CD8 genes is under the control of a complex array of regulatory elements distributed along the locus and characterized by DNaseI hypersensitivity. Here we describe the phenotype of mice in which hypersensitive sites 1 and 2 (HSS1 and 2) of DNaseI hypersensitive Cluster II (CII), which are located upstream of the CD8 alpha gene, were deleted by targeted homologous recombination of the endogenous locus. Knockout mice exhibit a variegated expression of the CD8 alpha gene, particularly among the immature CD4(+)8(+) TCR(lo) thymocyte population. We propose that HSS Cluster II regulatory elements are essential in ensuring initiation of chromatin remodeling and establishment of an open configuration in all developing thymocytes that undergo the double-negative to double-positive transition. Furthermore, these sequences contribute to the levels of expression of the CD8 alpha gene.

Involvement of IL-2/IL-2R system activation by parasite antigen in polyclonal expansion of CD4(+)25(+) HTLV-1-infected T-cells in human carriers of both HTLV-1 and S. stercoralis

The intermediate state of HTLV-1 infection, often found in individuals dually infected with Strongyloides stercoralis (S. stercoralis) and HTLV-1, is assumed to be a preleukemic state of adult T-cell leukemia (ATL). To investigate the effects of S. stercoralis superinfection on the natural history of HTLV-1 infection, we characterized peripheral blood samples of these individuals in Okinawa, Japan, an endemic area for both HTLV-1 and S. stercoralis and we studied effects of the parasite antigen on T-cells. The dually infected individuals showed a significantly higher provirus load and an increase in CD4(+)25(+) T cell population, with a significant, positive correlation. This increase was attributable to polyclonal expansion of HTLV-1-infected cells, as demonstrated by inverse-long PCR analysis of the integration sites. S. stercoralis antigen activated the IL-2 promoter in reporter gene assays, induced production of IL-2 by PBMC in vitro, and supported growth of IL-2 dependent cell lines immortalized by HTLV-1 infection or the transduction of Tax. Taken collectively, these results indicate that S. stercoralis infection induces polyclonal expansion of HTLV-1-infected cells by activating the IL-2/IL-2R system in dually infected carriers, an event which may be a precipitating factor for ATL and inflammatory diseases.

The puzzling world of murine T regulatory cells

T regulatory cells are essential for downregulation of undesired immune responses and prevention of autoimmune diseases, organ rejection, and graft versus host disease. This review describes the considerable progress made in the recent years in the characterization of the many subsets that constitute the puzzled world of murine T regulatory cells.

Hematopoietic cellular therapy: implications for the flow cytometry laboratory

Advances in hematopoietic stem cell transplantation, gene therapy, and immunotherapy have necessitated a host of novel monitoring procedures. Cell sorting is also coming of age as a clinical procedure designed to organize hematopoietic grafts for specificity of cellular components designed for individual patients or diseases. This article has focused on these novel developments in their historical context. The next generation of transplantation flow cytometry promises to be an exciting one.

Immunophenotypic characterization of peripheral T lymphocytes in Mycobacterium tuberculosis infection and disease

The cellular immune response probably plays a pivotal role in determining the clinical outcome after exposure to Mycobacterium tuberculosis. We used multi-parameter flow-cytometry to evaluate the distribution of T-lymphocyte subsets during infection and disease caused by M. tuberculosis. Samples were obtained from 71 volunteers to identify the T CD4+ and CD8+ lymphocyte numbers, and the activation plus memory/naïve phenotypes, as defined by CD38, HLA-DR, CD45RA and CD27 markers. Subjects were divided into 18 healthy volunteers without detectable reaction to purified protein derivative (PPD-), 18 health care workers with a recent conversion to PPD, 20 patients with active pulmonary tuberculosis (TBC) and 15 patients with treated TBC at 6 months of therapy. By multiple-comparison analyses, the T CD4+ lymphocyte number of the TBC group was lower than the PPD- group (P < 0.05). This difference was apparently lost after treatment. The higher and the lower number of naïve T CD4+ cells was observed in the PPD- and TBC group, respectively. CD8+ T lymphocytes were also statistically different among the four groups (P = 0.0002), lower in the TBC group (P < 0.05). CD8+ T lymphocyte activation was evaluated by the CD38 and HLA-DR surface expression. The percentage distribution of these markers was statistically different between the four groups (P = 0.0055). TBC patients had a higher percentage of CD38+ cells and mean fluorescence index, suggesting an overall increase of cell activation. These results suggest that peripheral T lymphocytes reflect cellular activation during TBC, along with possible redistribution of naïve, memory/effector and late differentiated memory/effector phenotypes in the peripheral blood after infection and disease caused by M. tuberculosis.