Faces and phases of human CD8 T-cell development.
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Antigens, CD↗
Biomedical subjects
R A van Lier
Publications and source records attributed to R A van Lier.
Aberrant expression and reverse signalling of CD70 on malignant B cells.
In normal lymphoid tissues the tumour necrosis factor-receptor family member CD27 and its ligand CD70 have a restricted expression pattern. Previously, we reported that expression of CD27 is deregulated in B-cell leukaemias and lymphomas. Here we show that, although infrequently expressed by normal human B cells in vivo, CD70 is found on 50% of B-CLLs, 33% of follicle centre lymphomas, 71% of large B-cell lymphomas, and 25% of mantle cell lymphomas. Interestingly, in the majority of leukaemias and lymphomas examined, CD70 was found to have a capped appearance, a feature that coincided with co-expression of CD27. Functional analysis showed that a subset of B-CLLs could proliferate vigorously in response to CD70 mAb but not to CD27 mAb. This response was synergistically enhanced by ligation of CD40 but inhibited by the presence of IL-4. Additional experiments indicated that the proliferative response was due to an agonistic signal delivered via CD70, rather than blocking of negative signalling by CD27. Thus, next to its role as ligand, in a subset of malignant B cells CD70 can operate as receptor and as such might contribute to progression of these B-cell malignancies.
Antigens, CD↗
Kawasaki disease: a maturational defect in immune responsiveness.
Kawasaki disease (KD), an acute febrile disease in children of unknown etiology, is characterized by a vasculitis that may result in coronary artery aneurysms (CAAs). In new patients with KD, a selective and prolonged T cell unresponsiveness to activation via the T cell antigen receptor CD3 was observed, whereas proliferation to other stimuli was intact. This "split T cell anergy" delineated KD from other pediatric infections and autoimmune diseases and correlated with CAA formation (P<.001). A transient immune dysfunction was also suggested by an incomplete responsiveness to measles-mumps-rubella (MMR) vaccination in patients with KD versus controls (P<.0001; odds ratio, 15.6; 95% confidence interval, 4.8-51.1), which was overcome by revaccination(s). The reduced responsiveness to MMR in patients with KD suggests a subtle and predetermining immune dysfunction. An inherent immaturity to clear certain antigens may be an important cause that precipitates KD and the immune dysregulation during acute disease.
Antibodies, Viral↗
Evidence that human CD8+CD45RA+CD27- cells are induced by antigen and evolve through extensive rounds of division.
We recently showed that circulating human CD8(+) effector cells have a CD45RA+CD27(-) membrane phenotype. In itself this phenotype appeared to pose a paradox: CD45RA, a marker expressed by unprimed cells, combined with absence of CD27, characteristic for chronically stimulated T cells. To investigate whether differentiation towards the CD45RA+CD27(-) phenotype is dependent on antigenic stimulation and involves cellular division, TCR Vbeta usage and telomeric restriction fragment (TRF) length were analyzed within distinct peripheral blood CD8(+) subsets. FACS analysis showed that the TCR Vbeta repertoire of CD8(+)CD45RA+CD27(-) cells differed significantly from that of unprimed CD8(+)CD45RA+CD27(+) cells. Moreover, in two out of six individuals large expansions of particular Vbeta families were observed in the CD8(+)CD45RA+CD27(-) subset. CDR3 spectrotyping and single-strand confirmation analysis revealed that within the CD8(+)CD45RA+CD27(-) population most of the 22 tested Vbeta families were dominated by oligoclonal expansions. The mean TRF length was found to be 2.3+/-1.0 kb shorter in the CD8(+)CD45RA+CD27(-) subset compared with the unprimed CD8(+)CD45RA+CD27(+) population, but did not differ substantially from that of memory type, CD8(+)CD45RA-CD27(+) T cells. These findings indicate that the CD8(+)CD45RA+CD27(-) cytotoxic effector population consists of antigen-induced, clonally expanded cells and confirm that the expression of CD45RA is not a strict marker of antigen non-experienced T cells.
CD8-Positive T-Lymphocytes↗
Quantitation of interferon gamma- and interleukin-4-producing T cells in synovial fluid and peripheral blood of arthritis patients.
OBJECTIVE: The balance between T cells able to produce interferon gamma (IFN-gamma) (type 1) and interleukin-4 (IL-4) (type 2) is considered to be important in the development of autoimmunity. In this study, we quantitated the percentage of both cell types in synovial fluid (SF) and peripheral blood (PB) of rheumatoid arthritis (RA) patients, non-rheumatoid arthritis patients and healthy controls. METHODS: After short-term stimulation of synovial mononuclear cells with phorbol ester and ionomycin, cytokine-producing cells were quantitated using an intracellular staining technique and flow cytometric analysis. RESULTS: Although no significant differences in CD8 + cells were found, significantly higher percentages of IFN-gamma-producing CD4 + (Th 1) and IL-4-producing CD4 + (Th2) cells were found in the peripheral blood of RA patients in comparison with healthy controls. However, the Th1/Th2 ratio was not different between the two groups. Comparative studies between PB and SF showed that in both RA and non-RA patients, percentages of Th1 cells were higher in SF than in PB, while Th2 cells were preferentially found in the PB, resulting in a higher Th1/Th2 ratio in the SF. The Th1/Th2 ratio in the SF correlated with disease activity as estimated by the erythrocyte sedimentation rate. CONCLUSION: These results are in agreement with the hypothesis that Th1 cells preferentially home to inflamed joints in both RA and non-RA patients, but show that this does not result in an altered Th1/Th2 ratio in the PB of RA patients.
Adult↗
Reconstitution of the T-cell compartment after bone marrow transplantation: restoration of the repertoire by thymic emigrants.
We have studied the reconstitution of the T-cell compartment after bone marrow transplantation (BMT) in five patients who received a graft-versus-host disease (GVHD) prophylaxis consisting of methotrexate, cyclosporin, and 10 daily injections (day -4 to day +5) of Campath-1G. This treatment eliminated virtually all T cells (7 +/- 8 T cells/microL at day 14) which facilitated the analysis of the thymus-dependent and independent pathways of T-cell regeneration. During the first 6 months, the peripheral T-cell pool was repopulated exclusively through expansion of residual T cells with all CD4(+) T cells expressing the CD45RO-memory marker. In two patients, the expansion was extensive and within 2 months, the total number of T cells (CD8>>CD4) exceeded 1,000/microL. In the other three patients, T cells remained low (87 +/- 64 T cells/microL at 6 months) and remained below normal values during the 2 years of the study. In all patients, the first CD4(+)CD45RA+RO- T cells appeared after 6 months and accumulated thereafter. In the youngest patient (age 13), the increase was relatively fast and naive CD4(+) T cells reached normal levels (600 T cells/microL) 1 year later. In the four adult patients (age 25 +/- 5), the levels reached at that time-point were significantly lower (71 +/- 50 T cells/microL). In all patients, the T-cell repertoire that had been very limited, diversified with the advent of the CD4(+)CD45RA+RO- T cells. Cell sorting experiments showed that this could be attributed to the complexity of the T-cell repertoire of the CD4(+)CD45RA+RO- T cells that was comparable to that of a normal individual and that, therefore, it is likely that these cells are thymic emigrants. We conclude that after BMT, the thymus is essential for the restoration of the T-cell repertoire. Because the thymic activity is restored with a lag time of approximately 6 months, this might explain why, in particular in recipients of a T-cell-depleted graft, immune recovery is delayed.
Adolescent↗
Prognostic value of Th1/Th2 ratio in rheumatoid arthritis.
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Antirheumatic Agents↗
Dissection of pathways leading to antigen receptor-induced and Fas/CD95-induced apoptosis in human B cells.
To dissect intracellular pathways involved in B cell Ag receptor (BCR)-mediated and Fas-induced human B cell death, we isolated clones of the Burkitt lymphoma cell line Ramos with different apoptosis sensitivities. Selection for sensitivity to Fas-induced apoptosis also selected for clones with enhanced BCR death sensitivity and vice versa. In contrast, clones resistant to Fas-mediated apoptosis could still undergo BCR-induced cell death. Based on the functional phenotypes of these clones, we hypothesized that both receptor-induced apoptosis pathways are initially distinct but may eventually converge. Indeed, ligation of both Fas and BCR resulted in cleavage of the IL-1beta-converting enzyme/Ced-3-like protease caspase 3 and its substrates Ac-Asp-Glu-Val-Asp-aldehyde and poly(ADP-ribose) polymerase. Markedly, qualitative differences in the caspase 3 cleavage pattern induced by Fas or BCR ligation were observed; whereas Fas ligation generated caspase 3 cleavage products of 19/20 and 17 kDa, only the latter cleavage product was found upon BCR cross-linking. The caspase inhibitor Val-Ala-Asp-fluoromethylketone blocked both Fas- and BCR-mediated apoptosis, but differentially affected caspase 3 cleavage induced by either stimulus. Finally, overexpression of a Fas-associated death domain (FADD) dominant-negative mutant protein was found to inhibit Fas-induced apoptosis but not BCR-induced apoptosis. Together our findings imply that Fas and BCR couple, via FADD-dependent and FADD-independent mechanisms, respectively, to distinct proteases upstream of caspase 3.
Adaptor Proteins, Signal Transducing↗
Characterization of the CD55 (DAF)-binding site on the seven-span transmembrane receptor CD97.
CD97 is an activation-induced antigen on leukocytes which belongs to a new group of seven-span transmembrane (7-TM) molecules, designated EGF-TM7 family. Family members, including EMR1 and F4/80, are characterized by an extended extracellular region with several N-terminal epidermal growth factor-like (EGF) domains. Alternative splicing of CD97 results in isoforms possessing either three (EGF1, 2, 5), four (EGF1, 2, 3, 5) or five EGF domains (EGF1, 2, 3, 4, 5). We recently identified decay accelerating factor (DAF, CD55), a regulatory protein of the complement cascade, as a cellular ligand of the smallest isoform. Employing mutants of CD97(EGF1, 2, 5) in which the EGF domains have been systematically deleted, we here demonstrate the necessity of at least three tandemly linked EGF domains for the interaction with CD55. Consistent with the involvement of different EGF domains, monoclonal antibodies directed against the first EGF domain as well as the removal of Ca2+, for which binding sites exist in the second and fifth EGF domain, blocked binding to CD55. Compared to CD97(EGF1, 2 ,5) the larger isoforms CD97(EGF1, 2, 3, 5) and CD97(EGF1, 2, 3, 4, 5) have a significantly lower affinity for CD55. Thus, alternative splicing may regulate the ligand specificity of CD97 and probably other members of the EGF-TM7 family.
Animals↗
Control of lymphocyte function through CD27-CD70 interactions.
In contrast to the expression of other TNFR/TNF family members, expression of CD27 and its ligand CD70 is predominantly confined to lymphocytes. High expression levels of CD27 appear to be dependent on proper ligation of antigen receptors, whereas for the induction of CD70 expression additional (co-stimulatory and/or pro-inflammatory) signals are required. Next to membrane-bound CD27 also a soluble form of CD27 is produced in the course of the immune response. Soluble CD27 (sCD27) is found in body fluids and can be used to monitor local and systemic immune activation. In addition, elevated serum concentrations of sCD27 are found in patients with B cell malignancies and levels of sCD27 strongly correlate with tumor load. Based on functional experiments and in vitro expression regulation data, we propose that interactions between activated lymphocytes in vivo can result in CD27-CD70 interactions that may regulate the size and function of antigen-primed lymphocyte populations.
Animals↗
Characterization of murine CD70, the ligand of the TNF receptor family member CD27.
Human CD70 (CD27 ligand) is a type II transmembrane glycoprotein belonging to the TNF family. The protein is not expressed on resting lymphocytes, but is rapidly induced on these cells after cellular activation. Importantly, interaction of CD70 with its receptor CD27 gives a costimulatory signal for lymphocyte activation. Whereas CD27 has been molecularly characterized in the mouse, murine CD70 (mCD70) was undefined until now. Here, we describe the cDNA cloning and initial characterization of mCD70 and the determination of its gene structure. mCD70 is a polypeptide of 195 amino acids that has 62% homology with its human counterpart. In analogy to human CD70, mCD70 transcript levels are strongly but transiently up-regulated during lymphocyte activation, which is in line with a role for the CD27-CD70 receptor pair early in the immune response. In accordance with the comitogenic activity of mCD27-specific mAb, recombinant mCD70 potently costimulates T cell proliferation. Finally, the mCD70 gene consists of three exons spanning approximately 4 kb of DNA and is localized on chromosome 17.
Amino Acid Sequence↗
Phenotypic and functional separation of memory and effector human CD8+ T cells.
Human CD8+ memory- and effector-type T cells are poorly defined. We show here that, next to a naive compartment, two discrete primed subpopulations can be found within the circulating human CD8+ T cell subset. First, CD45RA-CD45R0(+) cells are reminiscent of memory-type T cells in that they express elevated levels of CD95 (Fas) and the integrin family members CD11a, CD18, CD29, CD49d, and CD49e, compared to naive CD8+ T cells, and are able to secrete not only interleukin (IL) 2 but also interferon gamma, tumor necrosis factor alpha, and IL-4. This subset does not exert cytolytic activity without prior in vitro stimulation but does contain virus-specific cytotoxic T lymphocyte (CTL) precursors. A second primed population is characterized by CD45RA expression with concomitant absence of expression of the costimulatory molecules CD27 and CD28. The CD8+CD45RA+CD27- population contains T cells expressing high levels of CD11a, CD11b, CD18, and CD49d, whereas CD62L (L-selectin) is not expressed. These T cells do not secrete IL-2 or -4 but can produce IFN-gamma and TNF-alpha. In accordance with this finding, cells contained within this subpopulation depend for proliferation on exogenous growth factors such as IL-2 and -15. Interestingly, CD8+CD45RA+CD27- cells parallel effector CTLs, as they abundantly express Fas-ligand mRNA, contain perforin and granzyme B, and have high cytolytic activity without in vitro prestimulation. Based on both phenotypic and functional properties, we conclude that memory- and effector-type T cells can be separated as distinct entities within the human CD8+ T cell subset.
Adult↗
Defective TCR-mediated signaling in synovial T cells in rheumatoid arthritis.
In rheumatoid arthritis (RA), the functional status of T cells is incompletely understood. Synovial T cells display phenotypic evidence of former activation, but there is poor production of T cell-derived cytokines in the synovium. In addition, synovial T cell proliferation upon mitogenic and antigenic stimulation was decreased compared with that in peripheral blood T cells. Moreover, previous reports revealed that early Ca2+ rises induced by TCR/CD3 stimulation were decreased in RA T cells compared with those in healthy controls. To investigate the molecular mechanisms of RA synovial T cell hyporesponsiveness, we analyzed the TCR/CD3-mediated protein tyrosine phosphorylation in RA peripheral blood and synovial fluid (SF) T cells. SF T cells exhibited a decreased overall tyrosine phosphorylation pattern upon stimulation. Most notably, the induction of phosphorylation of p38 was virtually absent. Moreover, we found that tyrosine phosphorylation of the TCR zeta-chain, one of the most proximal events in TCR signaling, is clearly diminished in RA SF T cells. The decrease in tyrosine phosphorylation was accompanied by a decrease in detectable levels of zeta-protein within synovial T cells. These results suggest that a defective TCR signaling underlies the hyporesponsiveness of synovial T cells in RA.
Arthritis, Rheumatoid↗
Treatment with depleting CD4 monoclonal antibody results in a preferential loss of circulating naive T cells but does not affect IFN-gamma secreting TH1 cells in humans.
CD4(pos) TH1 T cells are considered to play a central role in a number of human autoimmune diseases such as rheumatoid arthritis (RA) and multiple sclerosis. Experimental treatment protocols aimed at selectively eliminating CD4(pos) T cells thus far have yielded disappointing clinical results. Here we analyzed phenotype and function of circulating T cells in multiple sclerosis patients treated with the chimeric CD4 mAb cM-T412 in a randomized, double-blind, placebo-controlled, magnetic resonance imaging-monitored phase II trial. Treatment resulted in a long-lasting depletion of CD4(pos) T cells but did not affect CD8(pos) T cell numbers. Analysis of CD4(pos) subpopulations showed that unprimed, CD45RA(pos)/R0(neg) lymphocytes were approximately three times more sensitive to the mAb than primed, CD45RA(neg)/R0(pos) T cells. Notably, within the CD45RA(pos) subset, T cells with phenotypic evidence of prior activation, i.e., expressing Fas, were relatively insensitive to cM-T412, compared with Fas(neg) cells. Remarkably, while a decrease in the number of IL-4-producing T helper 2 (TH2)-type cells in the anti-CD4 treated group was observed, numbers of IFN-gamma-producing T helper 1 (TH1)-type cells remained stable, resulting in a significant increase in the TH1/TH2 ratio. Our data show that treatment with depleting CD4 mAb does not eliminate the cells most strongly involved in the disease process, i.e., primed, IFN-gamma-producing TH1-type cells, and may therefore give an explanation for the lack of beneficial clinical effects of depleting CD4 mAb in human chronic autoimmune disease.
Adult↗
AICL: a new activation-induced antigen encoded by the human NK gene complex.
The NK gene complex on mouse chromosome 6 and its human homologue on chromosome 12 encode type II transmembrane proteins with a C-type lectin domain which trigger or inhibit target cell lysis by NK cells (NKR-P1, Ly49, NKG2, CD94) or function as cellular activators of various hematopoietic cells (CD69). We herein report the cDNA cloning of a new molecule, designated activation-induced C-type lectin (AICL), whose gene maps to the human NK gene complex proximal to the CD69 gene. AICL is a 149-amino acid (aa) polypeptide with a short cytoplasmic part of seven aa and a C-type lectin domain separated from the transmembrane region by only nine aa. The highest sequence similarity is found to the C-type lectin domains of CD69 and the chicken lectin 17.5. The presence of AICL transcripts in different cell types of hematopoietic origin, a rapid increase of gene transcription during lymphocyte activation, and a short half-life of the mRNA characterize AICL as a new, broadly expressed activation antigen.
Amino Acid Sequence↗
CD70 expression on T-cell subpopulations: study of normal individuals and patients with chronic immune activation.
CD70, the ligand of CD27, is a member of the TNF family, which includes molecules essential in the regulation of lymphocyte growth and survival. It is absent on resting lymphocytes but can be induced in vitro with activating stimuli. To extend information about its expression by different T-cell subpopulations, and its regulation in normal and pathologic conditions, highly purified T-cell subpopulations were studied: CD70 expression depended both on the activating stimulus and on the T-cell subset analyzed. PMA + Ionomycin induced CD70 on the large majority of CD8+ cells, but only on a minority of CD4+ cells (P < 0.002), and among these, preferentially on the CD45R0+ subset compared with the CD45RA+. The presence of CD4+ lymphocytes in cell cultures containing mixtures of T-cell subsets inhibited CD70 expression on CD8+ cells. On the contrary, stimulation with allogeneic cells induced CD70 expression also on CD4+ cells. Moreover, CD70 was found to be expressed by chronically in vivo activated T-cells, in conditions characterized by allogeneic and autoimmune reactions. These data suggest a possible role of CD70 in the pathogenesis of immune dysregulation; interestingly, this role may not be simply restricted to bind to, and signal through, CD27, since cross-linking of CD70 enhances the proliferative response induced by the stimuli used to elicit its expression.
Antigens, CD↗
Antigen-presenting cell-derived signals determine expression levels of CD70 on primed T cells.
Interaction between CD27 and its ligand CD70 provides a second signal for T-cell proliferation and tumour necrosis factor-alpha (TNF-alpha) production. Whereas CD27 is broadly expressed during T-cell development, expression of CD70 in vivo is restricted. To determine when CD27 CD70 interactions can occur in immune reactions, we here analysed the regulation of CD70 expression on activated T cells. Mitogenic stimulation of purified T cells with either immobilized CD3 monoclonal antibody (mAb) or a combination of CD2 mAb induces only low levels of CD70 membrane expression. Markedly expression of the CD27-ligand is strongly enhanced by antigen-presenting cells (APC) and APC-associated signals such as interleukin-1 alpha (IL-1 alpha). IL-12, TNF-alpha and CD28-ligation. In contrast, T-cell derived cytokines, such as IL-4, counteract CD70 up-regulation on activated T cells. Analysis of the small subset of circulating CD70+ T cells revealed that these cells have a primed phenotype as they express CD45RO and HLA-DR antigens and are in high frequency able to secrete interferon-gamma (IFN-gamma). We conclude that T-T interactions involving CD27 and CD70 are likely to occur relatively early in immune reactions, after productive T-cell priming by APC and that expression of CD70 on circulating T cells is a reflection of recent priming by antigen.
Antibodies, Monoclonal↗
Alteration of B-cell antigen receptor signaling by CD19 co-ligation. A study with bispecific antibodies.
The activation of B-cell antigen receptor-associated protein tyrosine kinases is an early and crucial event in B-cell signaling. Apart from the B-cell antigen receptor (BCR), the B-cell-specific transmembrane glycoprotein CD19 has also been shown to directly activate intracellular signaling cascades. In addition, because CD19 and the BCR are associated on the surface of activated B-cells, it has been proposed that close approximation between these two entities is crucial for optimal B-cell triggering. To test this hypothesis, bispecific antibodies were generated that bind membrane IgM and CD19 simultaneously. Although CD19 bispecific antibodies strongly induced tyrosine phosphorylation, they were, in contrast to muF(ab)2 fragments, unable to induce a proliferative response. Detailed analysis of the early signaling events showed that compared with muF(ab)2 fragments CD19 bispecific antibodies potently raised the intracellular [Ca2+], which was correlated with an efficient tyrosine phosphorylation of syk. Strikingly, the assembly of Grb2 complexes that may couple the BCR to p21(ras) was clearly altered by the CD19 bispecific antibody. In addition to the reported Shc and 145-kDa phosphoproteins, a prominent 90-95-kDa phosphoprotein resembling CD19 was detected in the Grb2 complexes. Thus, studies with CD19 bispecific antibodies show that CD19 co-ligation both quantitatively and qualitatively alters BCR signaling.
Adaptor Proteins, Signal Transducing↗