Memory CD4 T cells enhance primary CD8 T-cell responses

CD4 T-cell help is required for optimal memory CD8 T-cell responses. We have found that engaging preexisting CD4 Th1, but not Th2, memory cells at the time of CD8 T-cell priming results in increased CD8 effector responses to both bacterial and viral pathogens. The enhanced responses are characterized by increased numbers of cytokine-producing, antigen-specific cells. These findings suggest that engaging endogenous memory Th1 cells may increase cellular responses in an immunotherapy or vaccination setting.     

Decreases in alpha beta T cell receptor negative T cells and CD8 cells, and an increase in CD4+ CD8+ cells in active Hashimoto''s disease and subacute thyroiditis.

We examined peripheral lymphocyte subsets in patients with autoimmune thyroid disease, or subacute thyroiditis, in the active stage when possible. During destructive thyrotoxicosis arising from alpha beta T cell receptor (TCR) negative T (WT31-CD3+) cells and CD8 (CD4-CD8+) cells decreased and those of CD4+CD8+ cells increased slightly, resulting in proportional increases in CD4 (CD4+CD8-) cells, non-T, non-B (CD5-CD19-) cells, and the CD4/CD8 cell ratio. Changes were similar in active subacute thyroiditis. During stimulative thyrotoxicosis in active Graves' disease, the numbers of such T lymphocyte subsets were not changed, but only the number of CD5+ B (CD5+CD19+) cells increased markedly, resulting in proportional decreases in total T (CD3+) cells, alpha beta+ TCR T (WT31+CD3+) cells, CD8 cells, and non-T, non-B cells. A serial study of some of the patients showed opposite changes in alpha beta TCR- T cells, the CD4/CD8 cell ratio, and CD5+ B cells between the active stages of Graves' and Hashimoto's diseases. alpha beta TCR- T cells were mostly gamma delta TCR+ T (IIF2+ CD3+) cells in these patients. These data suggest that alpha beta TCR-T (gamma delta TCR+ T), CD8, and CD4+ CD8+ cells are important in thyroid destruction in Hashimoto's disease and subacute thyroiditis, and that CD5+ B cells are important in thyroid stimulation in Graves' disease.     

Contributions of CD4+, CD8+, and CD4+CD8+ T cells to skewing within the peripheral T cell receptor beta chain repertoire of healthy macaques.

Diversity in the peripheral T cell receptor repertoire of rhesus (Macaca mulatta) and pig-tailed macaques (Macaca nemestrina) has been studied by examining the profile of CDR3 lengths in TCR beta chains. Expressed CDR3 length distribution profiles for individual TCRBV families were obtained from total peripheral blood mononuclear cells (PBMC) and T cell subsets isolated from PBMC. These studies reveal that the T cell receptor repertoire of PBMC from healthy macaques often exhibits skewing in TCRBV family CDR3 profiles. The skewing of TCRBV family CDR3 profiles was evident as discrete expanded length(s) and was detected in up to 50% of the PBMC profiles. Analyses of separated T cell populations demonstrated that the CD8+ T cell subset was responsible for the majority of observed skewing in CDR3 length profiles. However, CD4+ T cells were also shown to contribute to the skewed peripheral PBMC repertoire in these animals. While certain TCRBV families frequently displayed skewed profiles, there was no concordance in the particular CDR3 lengths expanded among the different animals. Furthermore, an additional feature of the peripheral blood of the animals studied was the presence of an unusual population of extrathymic CD4 and CD8+ (double-positive) T cells (up to 9.6% in the PBMC of rhesus macaques). The double-positive T cells could be differentiated from CD4 single-positive and CD8 single-positive T cells by their increased surface expression of LFA-1 and decreased CD62L expression. The percentage of the double-positive T cells was higher in rhesus than pig-tailed macaques and contributed substantially to the peripheral T cell repertoire.     

Sequences of four previously undescribed human T-cell receptor beta chain variable genes.

T-cell receptor beta chain mRNA from 4 human T-lymphocyte clones was reverse transcribed, amplified by PCR, cloned in M13 and sequenced. Four hitherto undescribed variable genes were found. One of them (V beta-IW22) showed the highest homology (74.5%) to V beta 1. Two others (V beta-IW6 and V beta-IW10) belonged to the recently described V beta 21 family. The last gene (V beta-VW114) belonged to the V beta 9 family. However, the latter gene a is pseudogene because of an in-frame stop codon.     

Autoreactive CD4- CD8- alpha beta T cells to vaccinate adjuvant arthritis.

Studies suggested that experimental autoimmune diseases can effectively be prevented and treated by application of normal autoreactive T cells or autoreactive T cells in an attenuated form. In this study, several autoreactive CD4- CD8- T-cell clones (A2, A6, and A13 cells) were isolated for the first time from the draining lymph nodes of Lewis rats with adjuvant arthritis (AA). Surprisingly, intraperitoneal inoculation with A13 cells, but not A2 or A6 cells protected rats from AA both clinically and histologically. It was demonstrated that A13 cells were CD4- CD8- alpha beta T cells, and showed proliferative responses to irradiated syngeneic spleen cells (antigen-presenting cells; APC). Interestingly, A13 cells proliferated against concanavalin A (Con A) and staphylococcal enterotoxin B (SEB), but did not show any proliferation to Mycobacterium tuberculosis (Mt), or its 65 000 MW heat-shock protein (HSP). Rats protected from AA by inoculation with A13 cells showed a specific anti-idiotypic delayed-type hypersensitivity reaction compared with other autoreactive T cells (A2 or A6 cells). These findings demonstrate that AA can be suppressed by autoreactive CD4- CD8- alpha beta T cells, and these cells may be used as therapeutic agents in experimental autoimmunity.     

Preferential expression of IL-2 receptor subunits on memory populations within CD4+ and CD8+ T cells.

Using anti-Tac and anti-Mik-beta 1 monoclonal antibodies to alpha and beta subunits of the interleukin-2 receptor (IL-2R), respectively, a marked difference in expression of IL-2R subunits on blood CD4+ and CD8+ T cells was demonstrated between adults and newborns. In the adult blood, reciprocal expression of IL-2R alpha and IL-2R beta was observed in CD4+ and CD8+ T cells. Some CD4+ T cells expressing IL-2R alpha were often detected, but IL-2R beta + CD4+ cells were very few. On the other hand, CD8+ T cells expressed significant IL-2R beta but little IL-2R alpha. In marked contrast to adult individuals, both CD4+ and CD8+ T cells from the newborns, which seemed to consist mainly of naive populations, showed only negligible expression of IL-2R subunits. It was found that IL-2R subunits appeared to be preferentially expressed on CD4+ and CD8+ T cells with memory phenotypes in the adult blood. Isolated memory (CD45RO+) CD4+ and CD8+ T cells, unlike naive (CD45RO-) ones, were able to proliferate in response to exogenous IL-2 as well as the recall antigen. The present results suggest that IL-2R subunits expressed on circulating T-cell subsets may play an important role in memory T-cell function.     

T-cell receptor beta gene rearrangements in clones derived from human CD4-8- cells expressing natural killer cell activity.

Clones derived from highly purified human peripheral blood Leu 19+ cells in the presence of phytohaemagglutinin (PHA) and interleukin-2 (IL-2) expressed cytotoxic activity against natural killer (NK)-resistant as well as NK-sensitive targets. All 66 clones analysed had a germ line configuration of T-cell receptor (TCR) beta genes and 38/40 also had unrearranged TCR gamma genes. The two exceptions were both CD3+ clones, but these did not have a cytotoxic repertoire noticeably different from CD3- clones without TCR gamma gene rearrangements. Clones were also obtained from highly purified CD4-8- cells, most of which were also cytotoxic for NK-resistant and NK-sensitive targets. About 90% of these clones were CD3+ but only around 50% remained negative for CD4 and CD8 while a significant number (12.7%) were positive for both CD4 and CD8. All clones analysed had rearranged TCR gamma genes and most had also rearranged TCR beta genes, including 20/25 of the clones which were CD3+4-8-. Many of the clones showed two rearrangements of TCR beta genes, and 3/4 CD3- clones had rearranged TCR beta as well as TCR gamma genes. There was no correlation between cytotoxic activity and TCR gene status or phenotype of these CD4-8- derived clones, except that clones which were Leu 19+ tended to have higher cytotoxic activity against NK-sensitive and NK-resistant targets than Leu 19-clones. The results strongly indicate that TCR beta and gamma gene products are not involved in the cytotoxicity mediated by these clones. They also suggest that some CD4-8- cells may be capable of limited differentiation in vitro.     

Expression profile and clonality of T-cell receptor beta variable genes in normal human endometrium

PROBLEM: In spite of their key immunological role, alphabeta+ T cells residing in endometrium have not been extensively explored. We analyzed here expression profile of TCRBV genes in normal human endometrium compared with peripheral blood. METHODS: Samples were taken from normal reproductive women. RT-PCR using BV-gene specific primers was performed on blood and endometrial samples. After blotting, hybridization with radiolabelled probe and autoradiography, relative expression of each TCRBV family was determined. Clonal expansions of the over-expressed genes were assessed by CDR3 length polymorphism. RESULTS: Only one gene (TCRBV7) was expressed significantly and two other genes marginally more in the endometrium compared with blood. All three TCRBV genes examined showed a rather restricted pattern in the endometrium in contrast to polyclonal patterns in the blood. CONCLUSION: Our results stress the similarities between T cells residing in different mucosal tissues and provide a basis for future investigations about endometrial T cells and their antigen specificities in gynecological problems.     

MHC class II-independent CD25+ CD4+ CD8alpha beta+ alpha beta T cells attenuate CD4+ T cell-induced transfer colitis

CD4+ alpha beta T cell populations that develop in mice deficient in MHC class II (through 'knockout' of either the Aalpha, or the Abeta chain of the I-A(b) molecule) comprise a major 'single-positive' (SP) CD4+ CD8- subset (60-90%) and a minor 'double-positive' (DP) CD4+ CD8alpha beta+ subset (10-40%). Many DP T cells found in spleen, mesenteric lymph nodes (MLN) and colonic lamina propria (cLP) express CD25, CD103 and Foxp3. Adoptive transfer of SP but not DP T cells from Aalpha(-/-) or Abeta(-/-) B6 mice into congenic RAG(-/-) hosts induces colitis. Transfer of SP T cells repopulates the host with only SP T cells; transfer of DP T cells repopulates the host with DP and SP T cells. Anti-CD25 antibody treatment of mice transplanted with DP T cells induces severe, lethal colitis; anti-CD25 antibody treatment of mice transplanted with SP T cells further aggravates the course of severe colitis. Hence, regulatory CD25+ T cells within (or developing from) the DP T cell population of MHC class II-deficient mice control the colitogenic potential of CD25- CD4+ T cells.     

Differential requirement of CD28 for IL-12 receptor expression and function in CD4(+) and CD8(+) T cells

IL-12 is a potent inducer of IFN-gamma production and Th1 responses. Co-stimulation mediated by B7 has been shown to synergize with IL-12 for optimal IFN-gamma production and proliferation in vitro. In this study, we examined the requirement of CD28/B7 interactions for optimal induction of IL-12 receptor(R) beta1 and beta2 expression and IFN-gamma. IL-12-induced IFN-gamma production and STAT4 nuclear translocation were markedly reduced in CD28(-/-) splenocytes compared to that of wild-type (WT) splenocytes. Analysis of IL-12R expression revealed that IL-12 induced similar levels of IL-12R beta2 mRNA expression in WT and CD28(-/-) cells. In contrast, IL-12R beta1 expression was impaired in CD28(-/-) cells, indicating that expression of IL-12R beta1 and beta2 is differentially regulated by CD28. CD28(-/-) CD4(+) but not CD8(+) cells exhibited a defect in IL-12Rbeta1 expression that was associated with a marked decrease in IL-12 binding as well as IL-12-induced IFN-gamma production. IL-2 could restore IL-12R expression to CD28(-/-) CD4(+) cells, however, this occurred independently of IL-2-induced proliferation. Thus, these findings identify distinct requirements for CD28 in the capacity of CD4(+) and CD8(+) cells to respond maximally to IL-12.     

Unusual expression of CD94 on CD8+ TCR-alpha beta T cells in infectious mononucleosis

Infectious mononucleosis, caused by primary Epstein-Barr virus (EBV) infection, is usually a benign, self-limited lymphoproliferative disorder. We report a case of a 21-year-old woman who presented with fever, sore throat, severe neutropenia, and absolute lymphocytosis with atypical lymphocytes. In situ hybridization for EBV-encoded small RNA performed on the marrow aspirate clot specimen demonstrated scattered positive cells. EBV serology was compatible with primary infection. Flow cytometry immunophenotypic studies performed on aspirate material revealed a profoundly expanded population of CD8+ T-cell receptor (TCR)-alphabeta T cells with uniform expression of CD94. No evidence of a monoclonal T-cell population was found as assessed by V(beta) use with flow cytometry and by TCR gamma-chain gene rearrangement using a polymerase chain reaction method. Uniform expression of CD94 in an exuberant reactive proliferation of CD8+ TCR-alphabeta T cells in infectious mononucleosis has not been reported previously, and combined with atypical morphology might be misinterpreted as a malignant neoplasm.     

Alterations in T-cell receptor Vbeta repertoire of CD4 and CD8 T lymphocytes in human immunodeficiency virus-infected children

Perturbations in the T-cell receptor (TCR) Vbeta repertoire were assessed in the CD4 and CD8 T lymphocytes of human immunodeficiency virus (HIV)-infected children who were receiving therapy during the chronic phase of infection by flow cytometry (FC) and PCR analysis. By FC, representation of 21 TCR Vbeta subfamilies was assessed for an increased or decreased percentage in CD4 and CD8 T cells, and by PCR, 22 TCR Vbeta subfamilies of CD4 and CD8 T cells were analyzed by CDR3 spectratyping for perturbations and reduction in the number of peaks, loss of Gaussian distribution, or clonal dominance. The majority of the TCR Vbeta subfamilies were examined by both methods and assessed for deviation from the norm by comparison with cord blood samples. The CD8-T-lymphocyte population exhibited more perturbations than the CD4 subset, and clonal dominance was present exclusively in CD8 T cells. Of the 55 total CD8-TCR Vbeta families classified with clonal dominance by CDR3 spectratyping, only 18 of these exhibited increased expression by FC. Patients with high numbers of CD8-TCR Vbeta families with decreased percentages had reduced percentages of total CD4 T cells. Increases in the number of CD4-TCR Vbeta families with increased percentages showed a positive correlation with skewing. Overall, changes from normal were often discordant between the two methods. This study suggests that the assessment of HIV-induced alterations in TCR Vbeta families at cellular and molecular levels yields different information and that our understanding of the immune response to HIV is still evolving.     

CD8 T cells modulate CD4 T-cell and eosinophil-mediated pulmonary pathology in pneumocystis pneumonia in B-cell-deficient mice

Pneumocystis spp. pneumonia (PCP) in humans and in surrogate animal species typically occurs in the absence of CD4 T cells, as takes place during acquired immune deficiency syndrome. However, patients treated with highly active anti-retroviral therapy sometimes exhibit an exacerbation of diseases such as PCP that coincides with resurgent CD4 T cells, a phenomenon known as immune reconstitution disease. We used an animal model of PCP using the B-cell-deficient muMT mouse together with antibody-mediated depletion of various T-cell subsets to examine the role of CD4 and CD8 T cells in the development of pathology in PCP. Although overt pathology occurs in the presence of CD4 T cells only, CD8 T cells only, or both, pulmonary injury occurs via different paths, depending on the complement of T cells present. Surprisingly, profound damage occurred when only CD4 T cells were present, and this pathology coincided with enhanced recruitment and activation of eosinophils and strong type 2 cytokine polarization in the alveolar environment. In addition, CD8 T cells can act to moderate this CD4 T cell-mediated pathology, possibly by increasing the ratio of putative CD25+ suppressor CD4 T cells to CD25- effector CD4 T cells.     

T cell receptor V beta expression by mucosal T cells.

Immunohistochemistry with monoclonal antibodies to the T cell receptor V beta regions 5, 6, 8 and 12 was used to determine whether normal intestinal lymphocytes that are potentially exposed to many bacterially derived superantigens show any preferential expression of particular V beta regions compared with the blood. No difference between V beta expression in the mucosa and the blood was observed, suggesting that they share a common pool of alpha beta T cells and that there is no expansion of alpha beta T cells in response to bacterial "superantigens" in the gut. The T cell receptor V beta expressed by the activated T cells in the lamina propria of bowel from patients with Crohn's disease was also studied. There was no increase in V beta 8 expression in these cells, suggesting that the increase in V beta 8 observed in the blood and mesenteric nodes of patients with Crohn's disease is not of primary importance in the aetiology of the disease. Finally, V beta expression by mucosal T cells in coeliac disease was studied. There was no difference in V beta use by T cells in coeliac disease and those in the blood and normal jejunum.     

Lysophosphatidylcholine up-regulates CXCR4 chemokine receptor expression in human CD4 T cells

Oxidized low-density lipoprotein (OxLDL) is an inflammatory modulator in the atherosclerotic plaque. We examined the effect of lysophosphatidylcholine (lysoPC), a main phospholipid component of OxLDL, on inflammatory responses in human CD4 T cells. We found that lysoPC dose- and time-dependently increased expression of CXCR4, the chemokine receptor on CD4 T cells. This increase was inhibited by caffeic acid phenethyl ester or SN50, nuclear factor-kappaB inhibitors, and also by suppression of G2A expression, the specific receptor for lysoPC, using antisense oligonucleotide. lysoPC enhanced CD4 T cell chemotaxis in response to stromal cell-derived factor-1 (SDF-1), the exclusive ligand for CXCR4. lysoPC also enhanced SDF-1-stimulated production of inflammatory cytokines interleukin-2 and interferon-gamma by CD4 T cells activated by anti-CD3 immunoglobulin G. In conclusion, this study demonstrates that lysoPC directly modulates inflammatory responses in human CD4 T cells. The data suggest that the presence of lysoPC and SDF-1 in atherosclerotic lesions may trigger inflammatory responses mediated by CD4 T cells, which may play an important role in progression of atherosclerosis.     

Cutaneous T-cell lymphoma cells employ a restricted range of T-cell antigen receptor variable region genes.

Monoclonal antibodies that recognize the proteins specified by two families of T-cell antigen receptor variable region genes were assessed as clonal markers in cutaneous T-cell lymphoma (mycosis fungoides and Sezary syndrome). About 3% to 5% of tumors were expected to react with each antibody. However, 10 of 16 cases studied reacted with MAbs specific for the V beta 8 gene family. All the positive cases were examples of the plaque or tumor stages of CTCL. None of the cases of eczematoid or premycotic CTCL showed uniform reactivity with these antibodies. Unexpected use of one particular V gene family raises the possibility that CTCL derives from a distinct subpopulation of antigen- or virus-selected T cells.     

Diversity of T-cell antigen receptor variable genes used by mycosis fungoides cells.

The expression of T-cell antigen receptor beta-chain variable genes (V beta) was evaluated in 28 cases of mycosis fungoides. A novel polymerase chain reaction (PCR) technique was used to associate expression of particular V beta genes with monoclonal T-cell populations. In addition, the same biopsies used for PCR analysis were also examined for reactivity with a panel of seven monoclonal antibodies that specifically recognized V beta proteins from four different families. Only three cases clearly stained with the antibodies, a result consistent with a diverse set of V beta genes being used. This was confirmed by PCR analysis, which indicated that V beta genes from many different families were expressed by these tumors. Preferential use of the V beta 8 family, which had been previously use of the V beta 8 family, which had been previously reported for this disease, was not evident among the cases analyzed.     

Cross-linking of the T cell receptor complex with the subset-specific differentiation antigen stimulates interleukin 2 receptor expression in human CD4 and CD8 T cells

Nonpolymorphic interactions between the T cell differentiation antigens CD4 or CD8 and major histocompatibility complex (MHC)-encoded molecules have been postulated to participate in antigen recognition of MHC-restricted T cells. This would imply simultaneous binding of CD4/8 and of the T cell receptor complex (Ti/CD3) to MHC molecules on the stimulator or target cell. In this report experimental evidence is provided that simultaneous binding by antibodies of Ti/CD3 and of CD4 or CD8 leads to the expression of interleukin 2 (IL 2) receptors in resting human T cells and to their subsequent proliferation in the presence of recombinant IL 2 (rIL 2). This could be shown by using a novel anti-CD3 monoclonal antibody (BMA 030) which alone only marginally stimulates highly purified human T cells even when applied in cross-linked form. However, human T cell subpopulations could be stimulated to grow in the presence of rIL 2 when BMA 030 was fixed to a solid support in combination with antibodies to either CD4 or CD8. In limiting dilution experiments, the frequencies of CD4 and CD8 T cells activated by the antibody combinations were similar to those activated by phytohemagglutinin in the presence of irradiated adherent cells. No stimulation was achieved if both or one antibody was applied in soluble form. In contrast, soluble antibodies inhibited activation by solid-phase antibodies. Taken together, cross-linking of Ti/CD3 with CD4/8 seems to be essential for T cell activation in cases of ligands that bind but do not activate T cells on their own--a situation that may reflect the interaction of T cell receptors with MHC-encoded molecules in association with antigen.