A high proportion of the V delta 1+ synovial fluid gamma delta T cells in juvenile rheumatoid arthritis patients express the very early activation marker CD69, but carry the high molecular weight isoform of the leucocyte common antigen (CD45RA)

The Role of Gamma Delta T Cells in Autoimmune Rheumatic Diseases

Autoimmune rheumatic diseases (ARDs), affecting ~1-1.5% of all humans, are associated with considerable life long morbidity and early mortality. Early studies in the 1990s showed numerical changes of the recently discovered γδ T cells in the peripheral blood and in affected tissues of patients with a variety of ARDs, kindling interest in their role in the immuno-pathogenesis of these chronic inflammatory conditions. Indeed, later studies applied rapid developments in the understanding of γδ T cell biology, including antigens recognized by γδ T cells, their developmental programs, states of activation, and cytokine production profiles, to analyze their contribution to the pathological immune response in these disorders. Here we review the published studies addressing the role of γδ T in the major autoimmune rheumatic diseases, including rheumatoid arthritis, juvenile idiopathic arthritis, ankylosing spondylitis, systemic lupus erythematosus and scleroderma, and animal models thereof. Due to their unique properties spanning adaptive and innate immune functions, the ever deeper understanding of this unique T cell population is shedding new light on the pathogenesis of, while potentially enabling new therapeutic approaches to, these diseases.

γδT cells in Juvenile Idiopathic Arthritis: Higher Percentages of Synovial Vδ1+ and Vγ9+ T Cell Subsets Are Associated with Milder Disease

Objective.

To analyze γδT cell subsets in peripheral blood (PB) and synovial fluid (SF) of patients with juvenile idiopathic arthritis (JIA), and to correlate γδT cell subsets with clinical characteristics.

Methods.

γδT cell subsets as percentages of CD3+ T cells in samples of PB (n = 25) and SF (n = 93) were analyzed by flow cytometry in 93 JIA patients. The percentage of Vγ9+ γδT cells after 10 days of in vitro expansion with either interleukin 2 (IL-2) or isopentenyl pyrophosphate (IPP) plus IL-2 was determined.

Results.

Both Vδ1+ and Vγ9+ γδT cell subsets were detected in SF of all patients, but only the percentage of Vδ1+ cells was higher in SF compared to PB (p < 0.01). The distribution of γδT cell subsets was similar in different JIA subgroups, whereas antinuclear antibody (ANA)-positive patients had a higher percentage of SF Vδ1+ T cells than ANA-negative patients (p < 0.01). The percentage of SF Vδ1+ T cells was inversely associated with age at onset, recurrence of synovitis, and erythrocyte sedimentation rate; and that of SF Vγ9+ T cells was inversely correlated with age at onset and was higher in patients who recovered from disease (n = 15). IPP-induced expansion of SF Vγ9+ T cells correlated with disease remission, whereas the expansion of SF Vγ9+ T cells in media with IL-2 alone was significantly greater in patients with uveitis.

Conclusion.

The percentage of Vδ1+ and Vγ9+ γδT cells among the SF T cells and their ability to respond to IPP or IL-2 correlated with specific outcomes of JIA, suggesting their role in the immunopathogenesis of this disease.

T-cell and T-cell receptor abnormalities in the immunopathogenesis of juvenile rheumatoid arthritis

Several lines of indirect evidence suggest that the pathologic autoimmune responses in juvenile rheumatoid arthritis may be antigen-driven and T cell-mediated. These include (1) activation markers expressed on synovial T cells suggestive of previous activation in vivo; (2) persistent oligoclonally expanded T-cell populations accumulating preferentially in the synovial compartment; (3) some T-cell receptor complementarity-determining region 3 sequence similarities between different clones in an individual patient; and (4) T-cell derived cytokines of predominantly Th1 type. Whether T-cell contribution is limited to only early stages of the disease (as appears to be the case in collagen-induced arthritis) or T cells are required for the perpetuation of the inflammation at later stages as well, still remains to be determined.

The CD69 early activation molecule is overexpressed in human bone marrow mast cells from adults with indolent systemic mast cell disease

We have analysed the quantitative expression of surface CD69 antigen on human mast cells (MC), from both normal and pathological bone marrow (BM) samples, using flow cytometry. Our major aim was to analyse whether CD69 is constitutively expressed by normal BMMC and to explore the possible differences between CD69 expression by BMMC from normal controls and patients suffering from different pathological conditions. The constitutive expression of surface CD69 was clearly demonstrated in BMMC; however, systemic mast cell disease (SMCD) patients showed significantly higher levels of surface CD69 expression than healthy controls (P < 0.001), chronic lymphocytic leukaemia (P = 0.001), monoclonal gammopathy of unknown significance (P < 0.001), multiple myeloma (P < 0.001) patients, and myelodysplastic syndromes (P = 0.002). Furthermore, almost no overlap between the levels of CD69 expression on BMMC was observed between SMCD cases and the remaining groups of individuals except for the paediatric mastocytosis group (P > 0.05). From the other groups of patients, monoclonal gammopathy of unknown significance (P = 0.04), myelodysplastic syndromes (P = 0.03) and paediatric mastocytosis (P = 0.003) cases showed a significantly higher expression of surface CD69 as compared to normal subjects. In summary, our findings show that the CD69 antigen is overexpressed in SMCD patients.

Role of heat shock proteins in protection from and pathogenesis of infectious diseases

Increased synthesis of heat shock proteins (hsp) occurs in prokaryotic and eukaryotic cells when they are exposed to stress. By increasing their hsp content, cells protect themselves from lethal assaults, primarily because hsp interfere with the uncontrolled protein unfolding that occurs under stress. However, hsp are not produced only by stressed cells; some hsp are synthesized constitutively and perform important housekeeping functions. Accordingly, hsp are involved in the assembly of molecules which play important roles in the immune system. It is not surprising that due to their wide distribution and their homology among different species, hsp represent target antigens of the immune response. Frequent confrontation of the immune system with conserved regions of hsp which are shared by various microbial pathogens can potentiate antimicrobial immunity. However, long-term confrontation of the immune system with hsp antigens which are similar in the host and invaders may convert the immune response against these host antigens and promote autoimmune disease. This review provides an overview of the role of hsp in immunity with a focus on infectious and autoimmune diseases.

Participation of the CD69 antigen in the T-cell activation process of patients with systemic lupus erythematosus

Accumulating evidence has implicated T cells in the pathogenesis of systemic lupus erythematosus (SLE). The CD69 antigen is an integral membrane protein rapidly induced on the surface of activated lymphocytes. We obtained CD4+ and CD8+ T cells from normal subjects and patients with SLE. The percentage of CD69 expression in freshly isolated cells and after in-vitro incubation with mitogens was quantified by three-colour immunofluorescent staining. Expression of this protein was increased in both CD4+ and CD8+ T-cell subsets from SLE patients when compared with normal cells, although the difference was significant only in the CD8+ T-cell subset (P = 0.05). Cellular activation increased CD69 expression. When stimulated with anti-CD2/CD2R or phytohaemagglutinin (PHA), the percentage and absolute numbers of CD69+ cells were lower in patients than in controls. Addition of anti-interleukin (IL)-10 monoclonal antibody (MoAb) increased the percentage of in-vitro CD69 expression in SLE cells. These results suggest that the peripheral blood lymphocytes from patients with SLE have an intrinsic defect that alters their activation process, including the expression of CD69, and might explain some of the T immunoregulatory abnormalities observed in these patients.

Circulating Vdelta1+ T cells are activated and accumulate in the skin of systemic sclerosis patients

OBJECTIVE

An increased percentage of Vdelta1+/gamma/delta T cells has been detected both in the peripheral blood and bronchoalveolar lavage fluid of patients with systemic sclerosis (SSc). This study evaluated the subset distribution, activation status, and expression of cellular adhesion molecules, such as intercellular adhesion molecule 1 (CD54), very late activation antigen alpha4 (CD49d), and lymphocyte function-associated antigen 1alpha (CD11a), on circulating gamma/delta T cells, as well as their presence in the skin of SSc patients.

METHODS

We studied 12 patients with SSc and 16 healthy volunteer donors. The distribution, activation status, and expression of cellular adhesion molecules were studied by flow cytometry; their presence in SSc patient skin was evaluated by immunohistochemistry.

RESULTS

We found that the percentages and absolute numbers of peripheral blood gamma/delta T cells, CD16, CD8, CD45RO, CD25, HLA-DR, CD54, and CD11a coexpression did not differ significantly from those of the controls. CD49d gamma/delta T cells were significantly increased in SSc patients (2.3%) compared with controls (0.5%). A marked increase in the ratio of Vdelta1+ cells to gamma/delta cells was observed in the patients (72%) compared with the controls (31%). The Vdelta1+ subset showed a significant expression of both HLA-DR (83% of total Vdelta1+ cells) and CD49d (90% of total Vdelta1+ cells) compared with the controls (20.5% and 60%, respectively). In the skin, the absolute numbers of gamma/delta T cells were found in striking amounts in perivascular areas, particularly in the early edematous phase of SSc (22.58 in patients and 0 in controls); the majority of gamma/delta T cells were Vdelta1+ (19 in patients and 0 in controls). In the advanced phase of SSc, Vdelta1+ T cells were also increased compared with controls (3.5 versus 0).

CONCLUSION

Our results show that Vdelta1+ T cells express both adhesion molecules and activation markers, and strongly support gamma/delta T cell homing to sites of inflammation. The increase in the Vdelta1 subset suggests a selective V gene subset expansion.

Human intestinal Vdelta1+ lymphocytes recognize tumor cells of epithelial origin

gammadelta T cells can be grouped into discrete subsets based upon their expression of T cell receptor (TCR) variable (V) region families, their tissue distribution, and their specificity. Vdelta2+ T cells constitute the majority of gammadelta T cells in peripheral blood whereas Vdelta1+T cells reside preferentially in skin epithelium and in the intestine. gammadelta T cells are envisioned as first line host defense mechanisms capable of providing a source of immune effector T cells and immunomodulating cytokines such as interleukin (IL) 4 or interferon (IFN) gamma. We describe here the fine specificity of three distinct gammadelta+ tumor-infiltrating lymphocytes (TIL) obtained from patients with primary or metastatic colorectal cancer, that could be readily expanded in vitro in the presence of IL-1beta and IL-7. Irrespective of donor, these individual gammadelta T cells exhibited a similar pattern of reactivity defined by recognition of autologous and allogeneic colorectal cancer cells, renal cell cancer, pancreatic cancer, and a freshly isolated explant from human intestine as measured by cytolytic T cell responses and by IFN-gamma release. In contrast, tumors of alternate histologies were not lysed, including lung cancer, squamous cell cancer, as well as the natural/lymphocyte-activated killer cell-sensitive hematopoietic cell lines T2, C1R, or Daudi. The cell line K562 was only poorly lysed when compared with colorectal cancer targets. Target cell reactivity mediated by Vdelta1+ T cells was partially blocked with Abs directed against the TCR, the beta2 or beta7 integrin chains, or fibronectin receptor. Marker analysis using flow cytometry revealed that all three gammadelta T cell lines exhibit a similar phenotype. Analysis of the gammadelta TCR junctional suggested exclusive usage of the Vdelta1/Ddelta3/Jdelta1 TCR segments with extensive (< or = 29 bp) N/P region diversity. T cell recognition of target cells did not appear to be a major histocompatibility complex restricted or to be correlated with target cell expression of heat-shock proteins. Based on the ability of some epithelial tumors, including colorectal, pancreatic, and renal cell cancers to effectively cold target inhibit the lysis of colorectal cancer cell lines by these Vdelta1+ T cell lines, we suggest that intestinal Vdelta1+ T cell lines, we suggest that intestinal Vdelta1+ T cells are capable of recognizing cell surface Ag(s) shared by tumors of epithelial origin.

Immunopathogenesis of juvenile rheumatoid arthritis: role of T cells and MHC

Juvenile rheumatoid arthritis (JRA) is defined as chronic arthritis of unknown etiology appearing in patients less than 16 years of age. The disease is heterogeneous and is classified as pauciarticular, polyarticular, or systemic-onset disease. A few lines of evidence suggest that T cells are involved in the pathogenesis of the disease. T cells infiltrating the synovial membrane bear markers of activation and produce cytokines. The association of particular subtypes of JRA with certain HLA class II alleles provides strong evidence in favor of T cell involvement through an HLA-peptide-T cell receptor complex. Limited data from a few patients with JRA on T cell receptor transcripts from synovial membrane or synovial fluid cells point towards oligoclonality. This further supports the concept that T cells infiltrating the synovial membrane or extravasating into synovial fluid in patients with JRA reflect antigen-driven T cell proliferation.

Increased level of activated gamma delta lymphocytes correlates with disease severity in HIV infection

The lymphocyte subset expressing the gamma delta T cell receptor is increased in several infectious diseases including HIV infection. In this study the expression on gamma delta lymphocytes of the T cell activation markers CD25, HLA-DR and CD38, as well as the two isoforms of CD45, namely CD45RA and CD45RO, was determined in the peripheral blood of 56 HIV-infected intravenous drug users and 34 HIV-seronegative blood donors by two-colour flow cytometry. The percentage of gamma delta lymphocytes expressing HLA-DR and CD38 was higher than those in HIV-seronegative controls (P < 0.001 and P < 0.0001, respectively). Furthermore the HLA-DR+gamma delta+ lymphocytes correlated inversely with CD4+ T lymphocyte absolute count (P < 0.02 for both). The levels of gamma delta lymphocytes expressing CD25, CD45RA and CD45RO were similar to those in HIV-seronegative controls. Activated gamma delta lymphocytes may play a role in the HIV disease process and could provide a useful marker for disease progression.

V delta 1 gene usage, interleukin-2 receptors and adhesion molecules on gamma delta+ T cells in inflammatory diseases of the nervous system

This study investigates the expression of T cell receptor V delta 1 chain, interleukin-2 receptor alpha-chain (CD25) and adhesion molecules ICAM-1 (CD54), LFA-1 (CD11a/18) and CD44 on gamma delta+ T cells by three-color flow cytometry on cerebrospinal fluid (CSF) and blood cells in patients with multiple sclerosis (MS), other inflammatory neurological diseases (OIND) and other neurological diseases (OND). Of gamma delta + T cells in CSF and blood, 20-40% belonged to the 'epithelial' V delta 1 subtype. MS patients had the lowest levels in both CSF and blood, but the differences between the patient groups were not significant. The activation markers CD25 and CD54 were expressed by only a small proportion of gamma delta+ T cells and in a minority of patients. Although the occurrence of CD25+ and CD54+ gamma delta+ T cells was somewhat higher in CSF than in blood and in inflammatory diseases than in controls, the small numbers of CD25+ and CD54+ gamma delta+ T cells preclude establishing differences amongst compartments and patient groups. The adhesion molecules CD11a/18 and CD44 were constitutively expressed on all T cells. Therefore, we compared the relative antigen density per cell as measured by the relative fluorescence index (RFI) between CSF and blood, between the patient groups and between gamma delta+ and total T cells. The only difference encountered was a slightly higher expression of adhesion molecules on gamma delta+ compared to total T cells, with preference to MS patients. In conclusion, the V delta 1+ subtype of gamma delta+ T cells does not dominate in the CSF compartment.(ABSTRACT TRUNCATED AT 250 WORDS)

Selective activation of resting human gamma delta T lymphocytes by interleukin-2

In rheumatoid arthritis and other inflammatory diseases we and others have found that gamma delta T cells express activation antigens, suggesting that they are involved in the pathogenesis of these disorders. In this study we have stimulated peripheral blood mononuclear cells from normal donors with recombinant interleukin-2 (rIL-2) to see whether such a stimulus alone could activate gamma delta T cells. Short-term exposure (24-96 h) to rIL-2 selectively stimulated the gamma delta but not the alpha beta T cells to express activation antigens (CD69, CD25 and HLA-DR). Long-term culture (2 weeks) in rIL-2-containing medium caused a selective increase in the proportion of the gamma delta T cells and a corresponding reduction of the fraction of alpha beta T cells. Limiting dilution analysis revealed that approximately 1/60 of the gamma delta T cells responded to IL-2 in contrast to only 1/250 of the alpha beta T cells. Comparison of the expression of the IL-2 receptor (IL-2R) alpha and beta chains showed that there was a similar expression of the alpha chain on gamma delta and alpha beta T cells whereas the relative density of the beta chain was more than twice as high on gamma delta T cells. Both the IL-2-induced proliferation of gamma delta T cells and the expression of activation antigens on these cells could be inhibited by an anti-IL-2R beta monoclonal antibody (mAb) but not by an anti-IL-2R alpha mAb. Expression of CD69 on gamma delta T cells was dependent neither on the presence of B cells, monocytes, nor alpha beta T cells. Finally, we found that the IL-2-induced expression of CD69 was inhibited by activation of cAMP-dependent protein kinase and by inhibition of the Src-family of the tyrosine protein kinase, but not by inhibition of protein kinase C or by activation of the CD45 associated tyrosine phosphatase. The ability of gamma delta T cells to be activated by IL-2 is a feature which they have in common with natural killer cells. Moreover, it may be possible that the expression of activation antigens on gamma delta T cells in inflammatory diseases is an epiphenomenon secondary to IL-2 produced by activated alpha beta T cells.