Lack of suppressor cell activity in rheumatoid synovial lymphocytes

The role of different subsets of regulatory T cells in immunopathogenesis of rheumatoid arthritis

Rheumatoid arthritis (RA) is a common autoimmune disease and a systemic inflammatory disease which is characterized by chronic joint inflammation and variable degrees of bone and cartilage erosion and hyperplasia of synovial tissues. Considering the role of autoreactive T cells (particularly Th1 and Th17 cells) in pathophysiology of RA, it might be assumed that the regulatory T cells (Tregs) will be able to control the initiation and progression of disease. The frequency, function, and properties of various subsets of Tregs including natural Tregs (nTregs), IL-10-producing type 1 Tregs (Tr1 cells), TGF-β-producing Th3 cells, CD8⁺ Tregs, and NKT regulatory cells have been investigated in various studies associated with RA and collagen-induced arthritis (CIA) as experimental model of this disease. In this paper, we intend to submit the comprehensive information about the immunobiology of various subsets of Tregs and their roles and function in immunopathophysiology of RA and its animal model, CIA.

Functional analysis of rheumatoid factor-producing B cells from the synovial fluid of rheumatoid arthritis patients

OBJECTIVE

To understand the regulation of rheumatoid factor (RF) production in rheumatoid arthritis (RA), we studied IgM-RF production by B cells isolated from the synovial fluid (SF).

METHODS

Highly purified SF and peripheral blood (PB) B cells were isolated by negative selection in a fluorescence-activated cell sorter (FACS) and then cultured with either L cells, CD40 ligand (CD40L)-transfected L cells, or type B synoviocytes in the presence or absence of interleukin-2 (IL-2), IL-4, or IL-10. Total IgM and IgM-RF were detected after 14 days by enzyme-linked immunosorbent assay. Enzyme-linked immunospot assays were performed to detect cells that spontaneously produced immunoglobulin. SF B cells were also phenotypically characterized by FACS analysis.

RESULTS

Terminally differentiated CD20-,CD38+ synovial plasma cells (PC) present in the SF of RA patients secreted IgM-RF in the absence of a stimulus. IgM-RF production markedly increased when SF B cells were cultured in the presence of type B RA synoviocytes together with IL-10, but independently of CD40-CD40L interaction. Although CD20-,CD38+ PC could also be demonstrated in SF B cells from patients with other forms of arthritis, IgM-RF production was restricted to the SF B cell cultures of patients with seropositive RA. The frequency of IgM-RF-producing cells among IgM-producing PC in patients with seropositive RA was estimated to be as much as 50%.

CONCLUSION

These data demonstrate that terminally differentiated CD20-,CD38+ IgM-RF-producing B cells are specifically present in the inflamed joints of patients with seropositive RA. There is evidence that the local environment in the rheumatoid joint favors RF production. The relatively high frequency of IgM-RF PC in the SF B cell population provides evidence of a dominant RA-specific antigen-driven response in the development of the synovial PC repertoire.

The B cell repertoire of patients with rheumatoid arthritis. II. Increased frequencies of IgG+ and IgA+ B cells specific for mycobacterial heat-shock protein 60 or human type II collagen in synovial fluid and tissue

OBJECTIVE

A qualitative and quantitative analysis of the functional, antigen-specific B cell receptor repertoire of patients with rheumatoid arthritis (RA) in synovial and peripheral compartments.

METHODS

B cells were activated to grow and differentiate at high efficiency in vitro under limiting-dilution conditions. Isotype and specificity of the secreted Ig were tested by enzyme-linked immunosorbent assay.

RESULTS

In contrast to peripheral B cells, most synovial B cells had already switched to IgG/IgA in vivo. The frequencies of B cells specifically recognizing foreign antigens were decreased within the synovial population, whereas the frequencies of B cells specific for type II collagen, mycobacterial heat-shock protein 60 (hsp60), or IgG Fc fragments were significantly increased, revealing a negative correlation in terms of frequencies.

CONCLUSION

B cells specific for human type II collagen, hsp60, and IgG Fc fragments are produced and/or expanded locally within the affected joints of RA patients. Thus, the specific immune system is definitely involved in the local inflammatory and destructive processes.

Increment of CD8S6F1 cells in synovial fluid from patients with rheumatoid arthritis

OBJECTIVE

To investigate the role of CD8 cell subsets in the pathogenesis of rheumatoid arthritis (RA) and the phenotypes of T cells adherent or non-adherent to the target cells (endothelial cells and synovial cells) pre-treated with IL-1 beta.

METHODS

The expression of S6F1 on CD8 cells and that of an activation marker on CD8 cells and CD8 cell subsets was evaluated in specimens of peripheral blood and synovial fluid obtained from 15 patients with RA and 10 with osteoarthritis (OA) using a two- or three-colour immunofluorescence method for analysis.

RESULTS

The percentage of CD8S6F1 cells among CD8 cells in synovial fluid was significantly greater than that of peripheral blood. Synovial fluid from RA patients had a greater percentage of CD8S6F1 cells compared with either peripheral blood of matched patients or synovial fluid of OA patients. The percentage of CD8HLA-DR cells in synovial fluid was markedly greater than that in paired samples of peripheral blood in patients with RA. In the CD8S6F1 cells from both groups of patients, synovial fluid showed an increased percentage of HLA-DR cells compared with peripheral blood. Similar results were observed in CD8 cells lacking S6F1 expression (CD8S6F1-) from both groups of patients. There was no significant difference in the percentage of HLA-DR cells between CD8S6F1 and CD8S6F1- cell populations in peripheral blood. In contrast with peripheral blood, in synovial fluid of RA patients the percentage of HLA-DR cells in the CD8S6F1 cell population was markedly greater than that in the CD8S6F1- population. However, the percentage of HLA-DR cells in both cell populations was similar in synovial fluid of OA patients. In both the endothelial and the synovial cell adhesion assays, the percentage of CD8S6F1 among CD8 cells and the mean fluorescence intensity of S6F1 antigen on CD8S6F1 cells were significantly greater in the adherent T cell population than that in the non-adherent T cell population.

CONCLUSION

These results suggest that increased expression of S6F1 antigen and the increased percentage of HLA-DR cells on CD8 cells in synovial fluid may be responsible for the migration of these cells into inflamed synovial tissues, and for cellular interactions between these cells and synovial cells or the extracellular matrix.

Rheumatoid synovium is enriched in CD45RBdim mature memory T cells that are potent helpers for B cell differentiation

OBJECTIVE

To delineate the phenotype and function of synovial T cells in rheumatoid arthritis (RA).

METHODS

T cells from normal subjects or from RA peripheral blood (PB), synovial fluid (SF), or synovial tissue (ST) were analyzed phenotypically and functionally.

RESULTS

RA SF and ST T cells were found to be markedly enriched in CD45RAdim, CD45RO+, CD45RBdim mature memory cells, whereas in the PB, CD45RAbright naive T cells were more frequent than CD45RO+ memory T cells, and only a minority were CD45RBdim. SF and ST T cells proliferated less well and produced less interleukin-2 in response to mitogenic stimuli than did PB T cells. However, synovial T cells effectively promoted the production of Ig from normal B cells. Moreover, PB and synovial T cells differed in their capacity to down-regulate immunoglobulin production. Anti-CD3-stimulated PB T cells suppressed Ig production unless their proliferation was prevented with mitomycin C. In contrast, synovial T cells were potent helpers of B cell Ig production regardless of antecedent treatment with mitomycin C. To examine the relationship between the CD45RBdim phenotype and B cell help, CD45RBdim T cells were sorted from PB. As opposed to the findings with synovial T cells, suppression by control PB CD45RBdim T cells was observed, but only when large numbers were employed. B cell Ig production was enhanced after treatment of PB CD45RBdim T cells with mitomycin C. In contrast, healthy control sorted CD45RBbright or sorted CD4+, CD45RO+, CD45RBbright T cells did not support Ig secretion. After treatment with mitomycin C, both of these populations were more effective helpers of Ig production.

CONCLUSION

RA synovium is enriched in differentiated CD45RBdim memory T cells with potent helper activity and diminished capacity to down-regulate B cells, strongly implying an active role for these cells in the production of Ig in the synovium, and thus in the propagation of disease.

Acquired resistance to type II collagen-induced arthritis in rhesus monkeys is reflected by a T cell low-responsiveness to the antigen

Ten out of 14 rhesus monkeys developed arthritis after a single immunization with bovine type II collagen (B-CII). In contrast to primary resistant monkeys, arthritic animals showed a B-CII specific T cell proliferation during the induction phase of the disease. All surviving animals showed a full remission of the disease. Two monkeys acquired resistance to collagen-induced arthritis (CIA) after one period of disease, but in three animals a booster immunization with B-CII induced a slight flare-up. It is demonstrated that B-CII immunized rhesus monkeys have the capacity to restore resistance to CIA. The development of resistance to CIA is reflected by a decreased T cell responsiveness to B-CII. It is shown that the lack of IL-2 plays a role in B-CII-induced T cell low-responsiveness. A potential role of CD8+ T cells in the down regulation of the T cell response to B-CII is discussed.

Contrasuppressor T cell leukaemia: clonal proliferation of contrasuppressor T cells in a patient with granular lymphocyte-proliferative disorder

In 12 patients with granular lymphocyte-proliferative disorders (GLPD), we studied the capacity of patient peripheral blood mononuclear cells (PBMC) to promote or suppress polyclonal IgG synthesis by normal non-T cells in pokeweed mitogen-containing medium using an enzyme-linked immunosorbent assay. During the experiments we found a patient whose PBMC possessed contrasuppressor function. The patient was a 27-year-old female with anaemia and lymphocytosis of CD3+CD8+ granular lymphocytes (GL). Reconstitution experiments using normal donor non-T cells and CD4+ and CD8+ T cells showed that addition of the patient's CD8+ cells abrogated the suppressor cell function of normal CD8+ T cells. The patient's PBMCs were CD3+, CD8+, Ia+, and Vicia villosa lectin-adherent characteristics which are consistent with those of normal blood contrasuppressor T cells. The T cell receptor beta and gamma genes were found to be monoclonally rearranged. Ultrastructurally, this patient's GLs exhibited clusters of dense cytoplasmic bodies, which were not detected in the GL of other patients with GLPDs. These results indicate that the clonal proliferation of contrasuppressor T lymphocytes had occurred in this patient.

Selective migration of the human helper-inducer memory T cell subset: confirmation by in vivo cellular kinetic studies

The vast majority of T cells present in chronic inflammatory lesions are of the helper-inducer/memory (CD45RO+CD29+) phenotype; suppressor-inducer/naive cells (CD45RA+) are virtually absent. Furthermore, CD4+ T cells are found more frequently than CD8+ cells. Previous in vitro studies have suggested that this may be, in part, due to the increased capacity of CD45RO+CD29+ T cells to bind to endothelium and, thus, enter inflammatory foci but no in vivo evidence for preferential migration exists. To investigate this, suction blisters were generated over a purified protein derivative of tuberculin-induced delayed-type hypersensitivity lesions in humans and the phenotype of the blister cells was studied. At all time points, a preponderance of CD45RO+CD29+ cells over CD45RA+ cells and of CD4 over CD8 cells was demonstrated. Because of the rapid kinetics, this appears to represent preferential migration of these cell types rather than in situ proliferation or phenotype conversion. In addition the expression of the CD45RO but not the CD45RA antigen was up-regulated on blister T cells compared to blood T cells. Analysis of blister fluid showed high concentrations of interleukin 6 but not tumor necrosis factor-alpha or lymphotoxin. This study shows for the first time directly in vivo that CD45RO+ T cells migrate preferentially into inflammatory lesions. Furthermore, it illustrates the potential usefulness of this system in the analysis of the early phases of the immune inflammatory response.

Effects of a hydrosoluble bacterial extract from Escherichia coli (OM-89) on cytokine production by peripheral blood mononuclear cells from healthy subjects and patients with rheumatoid arthritis

OM-89 is a bacterial extract from escherichia coli, proposed as an immunomodulating drug for the treatment of rheumatoid arthritis (RA). Since immunological mechanisms may play a role in its action, the immunological effects of OM-89 were evaluated in vitro on peripheral blood mononuclear cells (PBMC) derived from healthy subjects and RA patients. Results indicated that in the absence of OM-89, production of the monokines interleukin-1 beta (IL-1 beta) and tumor necrosis factor-alpha (TNF-alpha) is increased, while that of the lymphokines interleukin-2 (IL-2) and interferon-gamma (IFN-gamma is decreased by phytohemagglutinin (PHA)-stimulated PBMC from RA patients as compared with PBMC from healthy subjects. In the presence of PHA, OM-89 enhanced the production of IL-1 beta, TNF-alpha, IL-2, and IFN-gamma. IL-1 beta and IL-2 curves obtained using increasing amounts of OM-89 did not differ depending on the source of PBMC. By contrast, in the presence of increasing amounts of OM-89, TNF-alpha secretion significantly higher and IFN-gamma secretion significantly lower with PBMC from RA patients compared to PBMC from healthy subjects. These data indicate that OM-89 acts on monocytes and T cells directly and/or indirectly and suggest a possible clinical activity by OM-89 in RA relative to its immunological properties.

Interleukin-2 inhibitor in rheumatoid arthritis synovial fluid does not inhibit mononuclear cell responses to mitogens

Synovial fluid (SF) from rheumatoid arthritis (RA) patients were tested for their ability to inhibit the proliferative responses of normal peripheral blood mononuclear cells (PBM) to mitogens and interleukin-2 (IL-2). SF significantly inhibited the responses to concanavalin A (CON A) and phytohaemagglutinin (PHA), but significantly enhanced the responses to IL-2. Similarly, SF mononuclear cells (SFM) were hyporesponsive to CON A and PHA compared with autologous PBM, but hyper-responsive to IL-2. It is concluded that an IL-2 inhibitor in RA SF is unlikely to be the cause of SFM hyporesponsiveness to mitogens.

Elevated soluble CD8 in the synovial fluid from patients with rheumatoid arthritis

Suppressor/cytotoxic T cells express the surface marker CD8, which can be measured in a soluble form in culture supernatants of activated human lymphocytes. Using a sandwich immunoassay, we assessed the levels of soluble CD8 (sCD8) in serum from patients with rheumatoid arthritis (RA; n = 82), patients with degenerative joint disease (DJD; n = 40), and healthy controls. There were no differences in serum sCD8 levels among these groups. In contrast, the levels of soluble CD8 in the synovial fluid (SF) from patients with RA (n = 53) were significantly increased compared with the levels in 23 samples from patients with DJD (821 +/- 110 U/ml versus 213 +/- 13 U/ml, p less than 0.001). Synovial fluid sCD8 levels in the RA group were strikingly elevated, to a maximum value of 5,026 U/ml. In the majority of RA SF specimens (39 of 53), the values were significantly higher in the SF than the serum. Although the RA group had higher values of sCD8, such values were not significantly correlated with measured laboratory or clinical parameters. Current clinical and laboratory methods of evaluating patients may not be adequate in dealing with the complexity and heterogeneity of RA. Soluble CD8 values may be useful in further grouping patients with this disease.

Inflammatory synovial T cells in different activity subgroups of patients with rheumatoid arthritis and juvenile rheumatoid arthritis

Mononuclear cells were eluted from synovial membranes of 39 patients with rheumatoid arthritis and 12 patients with juvenile rheumatoid arthritis. A considerable cell loss, about 50% or more, was seen during the various isolation steps. The CD4/CD8 ratio just after enzyme treatment (stage I) was significantly higher than at later stages, i.e. after removal of adherent cells (stage II, p less than 0.05) and after Isopaque Ficoll gradient centrifugation (stage III, p less than 0.01). This indicates a selective loss of CD4+ cells during isolation. In addition, stages I and II had higher CD4/CD8 ratios than peripheral blood of normal controls (p less than 0.01 and p less than 0.03), but not significantly higher than in peripheral blood of patients (p greater than 0.05). The CD4/CD8 ratio in eluted synovial membrane cells did not differ between patients with high and patients with low disease activity (p greater than 0.05). No correlation was found between any of the CD4/CD8 ratios and individual disease activity variables. Furthermore, a laboratory activity index and a disease outcome index were determined for each patient and no correlation was found between these indices and the CD4/CD8 ratios.

The preferential accumulation of helper-inducer T lymphocytes in inflammatory lesions: evidence for regulation by selective endothelial and homotypic adhesion

The mechanisms which lead to the accumulation of T lymphocytes into inflammatory lesions are not clearly understood. We have previously shown that synovial CD4 T lymphocytes are mostly CDw29+UCHL1+ (helper-inducer cells) and very few carry the CD45R antigen which identifies the suppressor-inducer subset. Synovial CD8+ cells are also CDw29+UCHL1+CD45R-. In the present study, lymphocytes from pleural and peritoneal inflammatory infiltrates were shown to have a similar phenotypic pattern. Furthermore, it was demonstrated that the CDw29+UCHL1+ subset had a greater ability than CD45R+ cells to adhere to endothelial cells and to form homotypic clusters. Differential surface expression of LFA-1 on the two subsets was also shown, but this could not account for the demonstrated adhesion differences. Differences in adhesion between CDw29+/UCHL1+ and CD45R+ cells may explain the preferential accumulation of CDw29+/UCHL1+ cells in inflammatory infiltrates and underlie some of the functional differences between cells taken from sites of chronic inflammation and those from peripheral blood.

Abnormal helper-inducer/suppressor-inducer T-cell subset distribution and T-cell activation status are common to all types of chronic synovitis

We have previously shown that rheumatoid synovial T cells are virtually all helper-inducer (CD4+4B4+UCHL1+) rather than suppressor-inducer (CD4+2H4+) cells. CD8 cells were also largely 4B4+. In addition, the majority of T cells were HLA-DR+. To investigate whether these findings were specific for rheumatoid disease, we studied the prevalence of these markers in a variety of chronic inflammatory arthropathies such as ankylosing spondylitis, Reiter's syndrome, and psoriatic arthritis. Again, almost 90% of the T cells were 4B4+UCHL1+ and only 11% were 2H4+; 50% expressed the HLA DR antigen. Thus this phenotypic distribution represents a final common pathway of chronic synovitis and may help to explain the immunopathology of the lesion.

Mononuclear cells recovered from inflammatory synovial membrane using fine-needle biopsy

A simple technique for fine-needle aspiration biopsy from the synovial membrane of arthritis knee joints preceded by lavage of the joint cavity is described. The procedure was atraumatic, well accepted, and could be performed on outpatients. Cells originating from the synovial membrane were obtained in 12 of 17 knees using a 1.2-mm cannula. The yield was 6.0 x 10(3) to 135 x 10(3) mononuclear cells. The cell populations could be expanded by stimulation with antigen and mitogen. The described fine-needle biopsy technique is of value when repeated sampling of synovial membrane cell populations is desired.

Phenotypes of peripheral blood T lymphocytes in rheumatoid arthritis and juvenile rheumatoid arthritis. Findings in patients with varying disease activity and clinical subgroups

The percentage of T4 and T8 positive cells in peripheral blood of 78 patients with rheumatoid arthritis (RA) and 26 patients with juvenile rheumatoid arthritis (JRA) was determined using a rosette technique. The T4/T8 ratio +/- SEM (standard error of the mean) in the RA patients was increased, 2.02 +/- 0.09, as compared with normal blood donors, 1.71 +/- 0.06 (p less than 0.02). The subgroups of RA patients who had a significantly increased T4/T8 ratio were ANA positive patients (p less than 0.02) and patients on no medication (p less than 0.05). In the total group of JRA patients the T4/T8 ratio was 2.01 +/- 0.12 versus 1.75 +/- 0.08 in controls (p = 0.061). Polyarticular JRA patients had an increased T4/T8 ratio as compared with controls (p less than 0.05) while patients with the pauciarticular form had a normal ratio (p greater than 0.10). No correlation between the T4/T8 ratio and a disease outcome index, a laboratory activity index, ESR, WBC, platelet count, hemoglobin, serum albumin, age and disease duration was found (K less than +/- 0.20, p greater than 0.10).

The T cell system in rheumatoid arthritis: activated or defective?

Rheumatoid Arthritis (RA) is characterised by the presence of activated lymphocytes in the synovial compartment, which are classically considered to be of particular importance to the pathogenesis of the disease. We have shown that activated lymphocytes are also found in the rheumatoid lymph nodes and peripheral blood, and that their proportions are increased in early or active disease. Double-labelling experiments showed that T cell subsets within the activated circulating lymphocytes resemble closely those found in the synovium, and suggested an important role for circulating activated lymphoid populations in the pathogenesis of RA. In vitro studies indicate that although rheumatoid lymphocytes express activation markers, they are functionally deficient. This is well established in the case of synovial lymphocytes. We have demonstrated that functional defects are also present in circulating rheumatoid lymphocytes, which show a decreased autologous mixed leucocyte response (AMLR), corrected partially by the addition of exogenous IL-2. They also proliferate poorly in response to PHA and produce significantly less IL-2 than normal controls. This is more marked in patients with active or complicated RA. These defects cannot be explained by a lack of CD4+2H4+ cells which we have shown to be the major IL-2-producing circulating lymphocyte subpopulation. These findings suggest an intrinsic-functional rather than a numerical deficiency of the IL-2 producing T cells in RA. In recent experiments we have shown that non-lymphoid populations, such as activated phagocytic cells, are also involved in the deficient rheumatoid T cell function, partly via the production of prostaglandins and reactive oxygen intermediates. We and others have demonstrated that the latter may significantly and selectively affect lymphocyte viability and function. These findings may explain the differences in the functional capacity of lymphocytes frequently observed between cells derived from different sites or at different stages of the disease. We suggest that it is not lymphocyte activation as such, but its defective nature, that is of pathogenetical importance in RA. Furthermore, the T cell system should not be viewed and studied in isolation in this disease, but its interactions with inflammatory cells should be taken into account.

Increased helper inducer and decreased suppressor inducer phenotypes in the rheumatoid joint

Cells isolated from the joints of patients with rheumatoid arthritis (RA) exhibit functional immune abnormalities, such as diminished suppressor activity, depressed response to mitogens, and enhanced immunoglobulin production. We sought to characterize the T lymphocyte subsets in the synovial fluid (SF) and peripheral blood (PB) of RA patients in an attempt to clarify the mechanism(s) responsible for these functional immune abnormalities. We used dual-immunofluorescence staining techniques with several combinations of monoclonal antibodies, including anti-4B4 and anti-2H4, which define, respectively, the helper inducer and suppressor inducer subsets of CD4+ (Leu-3+ and T4+) cells. Mononuclear cells from normal PB (n = 9), RA PB (n = 6), and RA SF (n = 9) were analyzed, after staining, by flow cytometry. We observed a significant increase (P less than 0.0002) in the number of cells bearing the helper inducer phenotype (CD4+, 4B4+), and a significant decrease (P less than 0.0002) in the number of cells bearing the suppressor inducer phenotype (CD4+, 2H4+), in RA SF compared with the levels in PB from RA patients or normal control subjects. We also observed that the CD8+, 2H4+ subset was significantly decreased (P less than 0.0001) in SF compared with that in PB. There was no significant difference in the lymphocyte subset levels in PB from RA patients and from normal subjects. These observations may account, in part, for the reduced suppressor activity, the poor response to mitogens, and the autologous mixed lymphocyte reaction, as well as the enhanced production of Ig and rheumatoid factor, that are observed in the rheumatoid joint.

B lymphocytes, B cell clones and rheumatoid factor antibodies in rheumatoid inflammation

This report focuses on the B lymphocytes and plasma cells in rheumatoid inflammation, and discusses the major autoantibodies in the pathogenetic mechanisms, i.e. the rheumatoid factor (RF) antibodies. We describe ways of raising human hybridomas that produce RF antibodies in rheumatoid arthritis (RA) in order to elucidate how these antibodies differ from the RF antibodies that are part of the normal immune response in man and animals, and from those in diseases other than RA, e.g. in M-components seen in mixed cryoglobulinaemia and in Waldenström's macroglobulinaemia. The preliminary results of these studies are presented and discussed.

Production of tumour necrosis factor-alpha, interferon-gamma and interleukin-2 by peripheral blood mononuclear cells of subjects suffering from rheumatoid arthritis

Using radio-immunoassay methods, the production of tumour necrosis factor-alpha (TNF-alpha), interleukin-2 (IL-2), and interferon-gamma (IFN-gamma) released by peripheral blood mononuclear cells (PBMC), maintained in culture and stimulated by phytohemagglutinin (PHA), was measured in normal subjects and patients with active or inactive rheumatoid arthritis (RA). Results indicated a dissociation between mitogenic response and secretion of mediators by PBMC under the influence of PHA in both normal controls and in patients with rheumatoid arthritis (RA). While [3H]thymidine incorporation was characterized by a rather bell-shaped curve with increasing concentrations of PHA, IL-2 and TNF-alpha displayed a linear dose-dependent increase. [3H]thymidine uptake by PBMC was in the same range in normal subjects as in patients with active and inactive RA, although cytokine secretion differed. The PBMC of patients with active RA produced less TNF-alpha, IL-2, and IFN-gamma than did those of the controls. In cases of inactive RA, the secretory response varied from subject to subject; mean values did not differ from those of normal subjects, except for those of IL-2 (p less than 0.01). The significance and the clinical relevance of these findings are discussed.

Reactive oxygen species selectively deplete normal T lymphocytes via a hydroxyl radical dependent mechanism

Chronic inflammatory synovitis is characterized by both lymphocytic infiltrates and persistent polymorph exudates. Activated polymorphs release reactive oxygen species (ROS) during inflammation, but the contribution that these make to the lymphocyte abnormalities associated with RA has been little studied. We therefore investigated the cytotoxic effects of the reactive oxygen species on human peripheral blood mononuclear cells (PBMC). PBMC were exposed to RPMI 1640 medium previously irradiated for up to 60 min. Consistent dose-dependent killing was observed at 24 h. Antioxidant studies indicated that H2O2 was the effective species. Catalase, which specifically degrades H2O2, gave almost total protection against cell death, while superoxide dismutase (SOD), thiourea, and mannitol were largely ineffective. Addition of exogenous H2O2 caused an identical pattern of cell death to that observed with irradiated medium. PBMC cultures supplemented with desferrioxamine (a ferric iron chelator) also gave significant protection, suggesting that H2O2 mediated its effects via OH radicals. Analysis of lymphocyte subpopulations showed that ROS caused a selective depletion, depending on the level of H2O2 present. Low levels induced a specific loss of CD8+ cells, while higher concentrations caused significant loss of CD4+ T cells as well. sIg+ B cells were unaffected at either concentration. This selective lymphotoxic effect of ROS may be of considerable importance in the pathogenesis of autoimmune inflammatory disease.

Phenotypes of T lymphocytes from peripheral blood and synovial fluid of patients with rheumatoid arthritis and juvenile rheumatoid arthritis. Evidence in favour of normal helper and suppressor functions of T lymphocytes from patients with juvenile rheumatoid arthritis

Lymphocytes from peripheral blood (PB) and synovial fluid (SF) from 21 patients with rheumatoid arthritis (RA) and 18 patients with juvenile rheumatoid arthritis (JRA) were studied with respect to T cell phenotypes using monoclonal antibodies in a rosette assay. The percentage of HLA-DR positive T cells was counted in PB and SF using indirect immunofluorescence. Suppressor cell activity of T cells from PB and SF was investigated by measuring the immunoglobulin production by pokeweed mitogen (PWM) stimulated B cells mixed with T cells at various ratios. The mean T4/T8 ratio was significantly lower in SF than in PB of both RA and JRA patients (p = 0.0062 and p less than 0.0001 respectively). The mean percentages of HLA-DR positive T cells were elevated in SF compared with PB in both patients groups (p less than 0.03 and p less than 0.04 in RA and JRA patients respectively). Mean suppressor cell activity and helper cell activity of T cells from SF and PB of JRA patients was normal. Thus there seems to be a dichotomy between the number of T8+ cells and suppressor cell function in mononuclear cells from SF of patients with JRA. This indicates that a considerable proportion of the T8+ cells in the SF do not have suppressor functions.

T-cell helper activity and B-cell function of synovial and blood lymphocytes from patients with rheumatoid arthritis or other forms of chronic arthritis

The helper effect of T cells on B-cell immunoglobulin (Ig) responses induced by pokeweed mitogen (PWM) or purified protein derivative of tuberculin (PPD) was studied in lymphocytes from synovial fluid (SF) and blood of nine patients with rheumatoid arthritis (RA) and eight patients with other forms of chronic arthritis. In PWM cultures the helper effect of SF T cells on Ig responses (IgG, IgM, IgA) of autologous and allogeneic blood B cells was lower than that of blood T cells (P less than 0.01). This decrease was more pronounced in patients with RA than in patients with non-RA. In PPD cultures no significant difference was found between the helper effect of SF T cells and blood T cells on the Ig responses of allogeneic blood B cells or on the IgG response of autologous blood B cells, whereas the helper effect of SF T cells on the IgM and IgA responses of autologous blood B cells was decreased. The Ig responses to PWM or PPD in cocultures of autologous blood B and T cells were not significantly different between patients and healthy controls. The PWM- and PPD-induced Ig responses of SF B cells were lower than those of blood B cells when cocultured with autologous blood T cells. SF B cells produced IgG but usually little IgM and IgA. Thus there was a dysfunction of SF B cells and of SF T cells in a PWM-driven system, but a fairly good helper function of SF T cells in a PPD-driven system.

Immunoregulatory function of T8 and T4 cells from synovial fluid and blood of patients with rheumatoid arthritis or other forms of chronic arthritis

The suppressor effect of synovial fluid (SF) T8 cells and blood T8 cells on the pokeweed mitogen (PWM)-induced T4 cell-dependent immunoglobulin production of autologous blood B cells was studied in nine patients with chronic rheumatic diseases (six patients with rheumatoid arthritis (RA), one patient with juvenile RA, and two patients with other forms of chronic arthritis). The suppressor effect of SF T8 cells was of the same magnitude as that of equal numbers of blood T8 cells from patients and healthy controls. However, the relative number of T8 cells was higher among SF T cells than among blood T cells in several cases. Good synovial T8 cell suppression was also demonstrated in coculture experiments where SF T4 cells and B cells were used. In PPD (purified protein derivative of tuberculin)-stimulated cultures the suppressor effect of SF T8 cells as well as of blood T8 cells from patients and controls was lower than it was in PWM-stimulated cultures. In most patients SF T4 cells showed a much better PWM-induced helper function than did non-fractionated SF T cells. Thus the poor PWM induced helper effect of non fractionated synovial T cells was in some cases mainly due to the suppressor effect of T8 cells, whereas in some cases there was also a deficient helper function of synovial T4 cells.

Cell-mediated immunity in rheumatic disease

Rheumatoid arthritis, systemic lupus erythematosus, and systemic sclerosis are the three most common systemic rheumatic diseases in which disordered immune function is thought to play a pathogenetic role. Each disease has different and characteristic abnormalities of the cellular immune system. In rheumatoid arthritis the identified abnormalities of immunoregulation are largely limited to specific antigens: Epstein-Barr virus and collagen. Systemic lupus erythematosus is characterized by exuberant B-cell activity with exaggerated humoral response, a diversity of autoantibodies, non-antigen-specific loss of suppressor cell function, and general suppression of cell-mediated immunity. In systemic sclerosis systemic defects of cellular and humoral immune function are mild, but the release of lymphokines and monokines at sites of inflammatory lesions is thought to be important in the pathogenesis of the disease. Similar immune cell-connetive tissue cell interactions are probably important in the propagation of rheumatoid synovitis. Thus, despite the many shared clinical and serologic features of these diseases as well as the presence of many patients who have clinically overlapping features of more than one of these entities, the immune defects and the immunopathogenesis of these disorders appear to be distinct.

Proliferating cells in the synovial fluid in rheumatic disease. An analysis with autoradiography-immunoperoxidase double staining

The subtype of the proliferating cells in the synovial fluid of patients with rheumatoid arthritis (RA), ankylopoietic spondylarthrosis (SPA), and osteoarthritis (OA) was studied with autoradiography-immunoperoxidase double staining. Of all spontaneously proliferating synovial fluid cells in chronic arthritis, 59 +/- 4% displayed T8 differentiation marker, whereas T4 (21 +/- 4%) and B (2 +/- 1%) cells were few. Of all T4+ and all T8+ lymphocytes, 0.55 +/- 0.1% and 0.90 +/- 0.1%, respectively, incorporated [3H]thymidine. The [3H]thymidine labelling index for B cells was 0.30 +/- 0.1%. This was in contrast to OA, in which no proliferating lymphocytes were observed in the synovial fluid. Our findings suggest that the predominance of proliferating T8+ cells in the synovial fluid reflects an underlying chronic inflammation. Because RA and SPA synovium is a site of intense immunoglobulin production, our finding of the predominance of activated, proliferating T8+ cells may also reflect a dissociation between phenotype and function as a reason for the chronicity of the joint inflammation.

Cellular immunohistopathology of acute, subacute, and chronic synovitis in rheumatoid arthritis

Cellular inflammation in rheumatoid arthritis (RA) synovial membrane was studied in biopsy specimens taken at different stages of synovitis and disease. Patients were classified into three subgroups: acute RA, subacute RA, and chronic RA. Inflammatory cells were characterised by a histochemical esterase method and immunohistochemical peroxidase-antiperoxidase (PAP) and avidin-biotin-peroxidase (ABC) staining. The amounts and distribution of inflammatory cells were different in various stages of the synovitis. In acute onset RA monocytes and granulocytes predominated, suggesting that the beginning of rheumatoid inflammation is similar to inflammatory reaction in general. The presence of T cells and also of plasma cells in subacute RA suggests underlying subclinical changes also in apparently healthy joints in RA. The most typical feature of prolonged synovitis in chronic RA was its intensity, characterised by the presence of large T cell and plasma cell infiltrates. Our findings suggest that the immunological mechanisms are secondary to the tissue damage caused by the initial inflammatory events of unknown cause. However, the immunological mechanisms may still play a central role in the aetiopathogenesis, because findings in chronic RA suggest a defective down-regulation of the immune response.

Etiology of rheumatoid arthritis

Definite genetic associations with immunological cooperative HLA-D(R) antigens have been demonstrated for rheumatoid arthritis (RA). Microbial etiology has not been proven, but some hope for the supporters of this view is still given by small viruses, plasmids of enteric bacteria or perhaps oncogen-like DNA-sequences. Yet, electrophoretical analysis of membrane proteins or surface glycoproteins of RA synovial cells does not show any differences compared to reference cells. Autoimmunity to several tissue elements has been demonstrated, but most of it is of secondary nature. Antigenicities of type II and III collagens are probably only contributory factors for HLA-DR4 positive individuals. Proteoglycans or minor cartilage collagens have not been extensively studied, so far. Endocrine, dietary or psychological influences might be triggering events for otherwise 'preloaded' individuals.

Characterization of the defective autologous mixed lymphocyte response in rheumatoid arthritis

In order to characterize the autologous mixed lymphocyte response (AMLR) in patients with rheumatoid arthritis (RA) and to define the relationship with disease activity, peripheral blood T lymphocytes were stimulated with either a B lymphocyte-enriched (B cells) or a macrophage-enriched (macrophages) population. A significant reduction (P less than 0.01 to P less than 0.001) of T cell proliferation stimulated both by B cells and macrophages was observed in patients with active disease. The B lymphocytes were significantly less stimulatory (P less than 0.02 to P less than 0.001) than macrophages in the patients compared with the controls. In the normal controls, macrophages in higher concentrations were capable of suppressing the B lymphocyte-stimulated AMLR, but macrophages from patients with RA were not excessively suppressive. A significant association (P less than 0.02) was observed between disease activity and the AMLR. Using the B-enriched population, the AMLR proliferative response was significantly associated (P less than 0.001) with the production of interleukin-2. Defects in proliferation could only be partially restored by the addition of interleukin-2. These data indicate that the defective AMLR observed in patients with RA is related to disease activity and is associated with altered cellular interactions among T lymphocytes, macrophages, and the B lymphocyte-enriched population.

The role of PNP enzyme in autologous rosette-forming cells

Since purine nucleoside phosphorylase has been associated with suppressor function in lymphocytes, enzyme activities were studied in autologous rosette-forming cells, a subset showing suppressor properties. Levels of this enzyme were higher in these cells than in other T cells. Con A induction of autologous red cell receptors and suppressor activity of T cells were both inhibited in dose-dependent fashion by Formycin B, a well known inhibitor of purine nucleoside phosphorylase. Inhibition of autologous rosette-forming cells was obtained after pulse treatment of cells with Formycin B for as little as 1 hr, whereas cell proliferation was only inhibited when Formycin B was present throughout culture; this confirms the independence of cell proliferation, and development of red cell receptors and suppressor activity. This study indicates a crucial role for purine nucleoside phosphorylase enzyme in induction of T cell suppressor activity.

Suppressor T cell function in patients with rheumatoid arthritis complicated by vasculitis

Concanavalin A (Con A)-induced suppressor T cell activity was determined in 10 rheumatoid arthritis (RA) patients with vasculitis, 34 RA patients without vasculitis, and 10 healthy individuals. The percent Con A-induced suppression in RA patients with vasculitis was 24.6. In contrast, it was 68.4% in those RA patients without vascular lesions. Further, the proportion of T cells reactive with OKT8 monoclonal antibody was also decreased in RA patients with vasculitis. Accordingly, the reduced Con A-induced suppressor T cell activity in these RA patients resulted, in part, from the reduction in the number of cells of the suppressor T cell subset. Those patients with vascular lesions also had a higher percentage of positive antilymphocytotoxic antibodies than RA patients without vasculitis. Since the differences in Con A-induced suppressor T cell activity and frequency of positive antilymphocytotoxic antibodies were so great, we believe RA patients with vasculitis could be recognized as a disease group distinct from RA patients without vasculitis.

Lymphocyte subpopulations in rheumatoid arthritis. An immunological, enzyme histochemical and morphological study

Peripheral blood lymphocytes (PBL) and synovial fluid lymphocytes ( SFL ) of patients with rheumatoid arthritis (RA) were examined with monoclonal antibodies, with coated ox red blood cells for the expression of Fc receptors for IgG or IgM (T mu and T gamma cells), and incubated for the demonstration of alpha- naphtyl acetate esterase and acid phosphatase. Equal percentages of OKT4 and OKT8 PBL were found in clinically active and inactive RA patients, and in healthy controls, but decreased percentages of OKT4 and increased percentages of OKT8-positive lymphocytes were found among the SFL . The percentages of T mu and T gamma cells, the presence of HLA-DR membrane antigens on T lymphocytes as well as the staining pattern for the enzymes revealed that SFL of patients with RA were highly activated, compared to PBL of RA patients and healthy controls. It can be concluded from this study that a single determination of OKT4 and OKT8-positive lymphocytes in the peripheral blood of RA patients has no predictive value for disease activity. However, the results of the experiments on T lymphocyte-activation clearly showed preferential activation of SFL compared to PBL, indicating that activation of lymphocytes occurs at the site of inflammation.

Increased DNA and/or RNA content of synovial fluid cells in rheumatoid arthritis: a flow-cytometry study

Flow-cytometry studies of DNA and RNA content were carried out in acridine orange-stained synovial fluid lymphocytes from 11 patients presenting with classical or definite rheumatoid arthritis. Monoclonal antibodies were used to detect specific T cell surface antigens (OKT3, OKT4, OKT8) and antigens associated with lymphocyte activation (OKIa 1, OKT10). T3 positive cell percentages were comparable to those of normal blood, although T4/T8 ratios were decreased in 4 out of 5 cases, and HLA-DR positive cells increased. Six out of 11 patients showed percentages of dividing cells varying from 2.2 to 7.2% as compared with less than 1% in the other patients and in normal blood. Nondividing cells were characterised by an increase in their RNA content compared with normal blood. A greater increase of RNA content was observed in patients with lower percentages of dividing cells, suggesting a G1/S block. Changes in cellular DNA and/or RNA contents provide a valuable parameter of lymphocyte activation, not necessarily linked to the expression of differentiation antigens by activated cells.

T lymphocyte subclasses in rheumatoid synovia as analysed with monoclonal antibodies and functional in vitro tests

Inflammatory synovial T lymphocytes were released by mincing rheumatoid arthritis (RA) affected synovium, by digesting the material with collagenase plus DNAse, and isolating by sheep red cell rosetting and density centrifugation. There was a wide variation in the T-helper (Tm, OKT4) and T suppressor (Tg, OKT8) lymphocyte ratio in the individual synovia, ranging from 0.55 to 1.57. The mean ratio of Tm/Tg lymphocytes as well as OKT4/OKT8 lymphocytes was somewhat lower in the synovium (and in the blood) of RA patients than in the blood of healthy persons, but the differences were not significant (p = 0.56 and 0.09, respectively). The helper and suppressive capacity of synovial T lymphocytes on T-dependent B-cell maturation to immunoglobulin synthesis was analysed by co-culturing them with normal B or (unseparated) T+B cells in the presence of pokeweek mitogen. Eluates where the helper/suppressor ratio was above 1.2 produced at least some T cell help and lacked suppressor capacity, whereas eluates with a T helper/suppressor ratio below 1.20 provided a strong suppression and lacked the capacity of T-cell help. On the whole, we were unable to demonstrate any uniform pattern of inflammation with regard to T-cell subsets in the rheumatoid synovium. However, it seems that monoclonal antibodies provide good markers with which to analyse the inflammatory T cells in situ, and that these markers correlate well to the functional capacity of these cells in vitro.

Contrasuppression: the second law of thymodynamics, revisited

The data discussed here touch upon several issues in the evolving story of T cell contrasuppression, the underlying theme being that of heterogeneity. First, there is the issue of function. We are considering here only those cells that affect the function of secretory differentiation. We have evidence that different contrasuppressor cells exist for clone growth, but have not yet studied them in the same depth as those for secretory differentiation. Second, there is the important issue of target cells. In this article by Green and Gershon it is pointed out that there is clear evidence that contrasuppressor effects can work by protecting helper cells from suppressor cell effects in vitro. On the other hand, direct additional inhibition of the suppressor cells themselves has not been excluded. The latter point is also true in our system. However, we must suppose for the sake of simplicity in many of our experiments that if suppressors are not the target of the contrasuppressor effects then the B cells themselves probably are. This is because the tumor cells engage in a spontaneous rate of growth and differentiation in the absence of help or suppression. When T cell-dependent, specifically triggered effects reduce this spontaneous behavior, then a suppressive effect must have been delivered directly to the B cells. This is a simplifying assumption which is attractive, but since the experiments are carried out in vivo and thus may be affected by some factors that we have not yet recognized, we are not confident on its "intuitive" appeal. A third issue revolves around triggering specificity. One of our contrasuppressors exhibits the phenomenon of carrier crossreactivity (CRCS) and is thus behaving in accord with expectations aroused by Green and Gershon in this review. The other cell is apparently quite carrier specific (SCS). The meaning of this is not at all clear, but its potential significance may somehow be related to a sort of "mirror image" relationship of the two cells. Thus, for example, in other experiments not discussed here, we have noted that the CRCS binds to 315 protein-coated plates, but as noted here counteracts a suppressive effect which is generated by cells which do not adhere to these plates. In contrast to SCS does not bind to 315 plates and yet, as noted here, appears to counteract a suppressor effect generated by cells which do adhere to 315 plates.(ABSTRACT TRUNCATED AT 400 WORDS)

Quantitative and qualitative impairment of immunoregulatory cells in the circulation of rheumatoid arthritic patients

T cells bearing receptors for the Fc portion of IgM or IgG, TM or TG cells respectively, in the peripheral blood of RA and OA patients were found significantly less often when compared with TM and TG cells in the peripheral blood of normal donors. Using culture combinations of TM, TG and B cells, we were able to demonstrate that the B cells in the peripheral blood of RA patients were constantly of low functional competence and the TMcells varied between highly competent and low competent. RATG cells in general suppressed normal B-lymphoblast differentiation.

Analysis of T-cell cultures and clones from a patient with classic rheumatoid arthritis--evidence for the existence of autoreactive T-cell clones in blood and synovial fluid

Using lectin-free IL-2 as the only initial stimulus, bulk cultures and T-cell clones were established from synovial fluid (SFL) and peripheral blood lymphocytes (PBL) of a patient with rheumatoid arthritis (RA). The cloning efficiency of growing bulk cultures was 3%-4% as evaluated by Poisson statistics and was not enhanced by the addition of autologous synovial fluid or serum. The majority of the cloned T cells expressed the OKT8+ phenotype; several clones were OKT4+ and one clone expressed OKT8+ and OKT4+ antigens. None of the cloned T cells exhibited high NK or lectin-dependent cytotoxicity, although bulk cultures had high NK activity. In primed lymphocyte typing responses, bulk cultures and two T-cell clones established from rheumatoid SFL and PBL showed consistent autoreactivity, which we have never before observed with MLC-derived bulk cultures and T cell clones. One of the autoreactive rheumatoid T-cell clones (B25) was found to provide strong helper activity to autologous B cells in the absence of mitogen. Attempts to reveal reactivity of RA-derived T-cell clones to microbial antigens have so far only been successful with Mycoplasma pneumoniae preparations. Careful analysis of this reactivity revealed, however, that Mycoplasma pneumoniae induces a stimulator cell-dependent mitogenic effect rather than an antigen-specific MHC-restricted T-cell proliferation.

T-cell immunoregulatory functions in rheumatoid arthritis patients

We have studied the immunoregulatory function of T8+ (suppressor/cytotoxic) and Leu3a+ (inducer/helper) T cells from rheumatoid arthritis (RA) patients by measuring the effect of these T-cell subpopulations on the generation of immunoglobulin-secreting cells by normal allogeneic B cells after stimulation with pokeweed mitogen (PWM) in vitro. When T8+ or Leu3a+ cells from blood or synovial tissue from nine patients were substituted for T8+ or Leu3a+ cells, respectively, from normal blood mononuclear cells (MNC), RA T8+ cells showed an increased suppressor activity, whereas RA Leu3a+ cells were, except for one patient, weak augmentors. Unreplaced normal MNC and MNC replaced with allogeneic normal T-cell subpopulations responded equally to PWM. When T8+ plus Leu3a+ cells from the same patient replaced normal T cells, high B-cell responses were detected. Normal T8+ plus Leu3a+ cells generally supported the response to a lower degree. Substitution with two allogeneic T-cell subpopulations did not result in a B-cell response to PWM. Thus, whereas RA T8+ seemed to be strong suppressors and RA Leu3a+ cells weak augmentors by themselves, together they are possibly able to generate a B-cell stimulatory potential that might be of pathogenetic significance in the patients.

Eluted rheumatoid synovial tissue T cell subsets and HLA-DR bearing cells at different stages of fractionation

By using monoclonal antibodies of the OK series in the indirect immunofluorescence technique we wanted to enumerate T cell subsets and HLA-DR-bearing cells of patients with classical rheumatoid arthritis after the cells were eluted from rheumatoid synovial tissue and at different stages of two cell fractionation procedures. The procedures were an overnight incubation on plastic flasks or a brief (7 min) fractionation on nylon wool columns, both followed by Isopaque-Ficoll gradient centrifugation. 70-90% HLA-DR+ cells and 15-30% T3+ (T cells) were initially observed. Plastic flask incubation and gradient centrifugation reduced the mediam number of HLA-DR+ cells to 55% while the number of T3+ cells increased to 60-75%, the number of T4+ (helper/inducer T cells) and T8+ (cytotoxic/suppressor T cells) usually being about equal. The other fractionation procedure left essentially the same relative proportions of cells bearing these markers even though the cell yield was 5-10 times greater than for the plastic flask fractionation. About 30% of the T cells were calculated to bear HLA-DR antigens, indicating local activation in vivo.

Impaired conA suppressor cell activity in patients with rheumatoid arthritis shows normalization during fasting

Normal controls and patients with rheumatoid arthritis (RA) were investigated with respect to quantitative lymphocyte proliferation (LP) after concanavalin-A (conA) activation and to conA-induced suppressor cell activity (conA-SC). Measurements and assessment of RA activity were made at the beginning and end of a 10-day fast. The controls showed depressed (p less than 0.05) LP at the end of the fast, but no change in conA-SC activity. The RA group showed subnormal (p less than 0.05) LP and conA-SC (p less than 0.01) at the beginning of the experiment. After fasting they showed clinical improvement, the LP was not further depressed, and the initially low conA-SC had become normal.

Quantitation of cells secreting immunoglobulins after elution from rheumatoid synovial tissue

Mononuclear cells (MNC) eluted from rheumatoid synovial tissue of 16 patients with rheumatoid arthritis were examined for immunoglobulin-secreting cells (ISC). Immediately after elution and separation synovial tissue MNC contained considerable numbers of ISC. IgG and IgA ISC were more abundant than IgM ISC. At the same time there were low numbers of ISC in blood. Synovial tissue ISC were lost during incubation with pokeweek mitogen (PWM), possibly because tissue MNC were already maximally triggered in vivo. This was in contrast to blood MNC, in which the number of ISC increased significantly during incubation with PWM.

In situ characterization of mononuclear cells in rheumatoid tissues, using monoclonal antibodies. No reduction of T8-positive cells or augmentation in T4-positive cells

The reactivity of monoclonal mouse anti-human antibodies specific for mononuclear cell surface antigens were studied by the indirect immunofluorescence technique in frozen synovial tissue sections from patients with rheumatoid arthritis (RA). Most of the proliferating synovial lining cells were positive for HLA-DR antigens and monocyte-specific antigens, since they reacted with the OKIa1 and OKM1. Cells positive for HLA-DR and monocyte antigens were also seen scattered or in small nests in the synovial stroma, probably representing synovial cells or monocytes/macrophages. Some of the HLA-DR-positive cells may also be B lymphocytes or activated T cells. Endothelial cells were also HLA-DR antigen-positive. Monoclonal antibodies with specificity for all T cells (OKT3), for helper/inducer cells (OKT4), and for suppressor/cytotoxic cells (OKT8) reacted with cells often located in follicle-like structures around vessels. Cells with the T4 phenotype tended to be located in the centre of the follicles, whereas the T8 positive cells were more peripherally situated. In most instances fewer cells were positive for the T8 than for the T4 marker. In some instances there was as many T8-positive cells as T4-positive cells. Complete lack of T-lymphocyte subpopulations was not seen.

Autologous mixed lymphocyte reactions in patients with rheumatoid arthritis and juvenile rheumatoid arthritis: both non-T cells and in-vivo-activated T cells can act as stimulator cells

The lymphocyte responses in autologous mixed lymphocyte reactions (AMLR) between irradiated non-T and T lymphocytes from the peripheral blood (PB) of rheumatoid arthritis (RA) and juvenile RA (JRA) patients were decreased compared with the AMLR responses of normal PB lymphocytes. Normal AMLR responses were seen in synovial tissue and the synovial fluid lymphocytes from RA and JRA patients. The lymphocyte responses were also decreased in AMLR between irradiated non-T cells from peripheral blood and T cells from synovial tissue (ST) in RA patients and between irradiated non-T from PB and synovial fluid (SF) T cells in JRA patients. However, when irradiated non-T cells from ST of RA patients or from SF of JRA patients were mixed with autologous PB T lymphocytes, increased lymphocyte responses were observed. SF T lymphocytes and ST T cells were also shown to stimulate autologous PB T lymphocytes.