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

Conserved motifs in rheumatoid arthritis synovial tissue T-cell receptor beta chains

Rheumatoid arthritis is genetically linked to major histocompatibility complex (MHC) molecules (HLA-DR4 and related molecules) and characterized pathologically by high levels of HLA-DR expression and infiltration of proliferative of synovial tissue with CD4+ T lymphocytes. T-lymphocyte activation is driven by specific signaling through polymorphic alpha/beta T-cell receptors (TCRs) that are reactive with antigen-MHC complexes present at the sites of inflammation. We are interested in characterizing rheumatoid TCRs molecularly to ascertain potential binding surfaces for antigen+MHC in synovial tissue. Accordingly, we have recently investigated the TCR alpha and beta chain heterogeneity in a series of 10 rheumatoid synovia obtained at the time of joint surgery. The most frequently detected V beta families were V beta 12, 14, and 17, each of which was found in 80% of specimens. We report here the molecular cloning and sequence analysis of 20 cloned V beta segments amplified with a V beta 14 family-specific TCR primer, and six cloned V beta segments amplified with a V beta 17 family-specific TCR primer from four rheumatoid synovia. Comparison with the data base revealed that these sequences belonged to the closely related V beta 3, V beta 14, and V beta 17 families. Dominant clones were apparent in two of the individuals by the presence of identical V-D-J regions, suggesting an antigen-driven process. Amino acid sequence analysis revealed a conserved motif in the putative fourth hypervariable region or CDR4. Molecular modeling of this epitope suggests that charged side chains are available for binding to ligand structures (e.g., antigen, MHC, or superantigen). We suggest this epitope may play a role in the molecular pathogenesis of rheumatoid arthritis.

Restricted heterogeneity of T cell receptor transcripts in rheumatoid synovium

RA is characterized by massive proliferation of synovial tissue, accompanying infiltration of the tissue with CD4+ T lymphocytes, and a genetic linkage to the MHC antigen HLA-DR4. Since T cells are restricted by class II MHC molecules such as DR4, this suggests a direct role for these CD4+ cells in pathogenesis. To investigate T cell receptor (TCR) usage in RA, we used oligonucleotide primers specific for each of the major alpha and beta TCR subfamilies to amplify cDNA derived from whole synovium or synovial tissue T cell lines in a family-specific manner. Detection of amplified DNA was facilitated by utilizing oligonucleotide probes derived from the constant regions of the TCRs. The TCR repertoire present in the synovial T cell lines was quite heterogeneous, with an average of 15 alpha chains and 15.8 beta chains detected. When synovial tissue was analyzed, the predominant TCR subfamilies detected tended to be more restricted, with an average of 4.6 alpha chains and 8.6 beta chains detected. This compared with an average of six alpha chains and 12 beta chains in nonrheumatoid synovial samples. The average percentage of synovia positive per TCR beta family was significantly lower for RA versus non-RA specimens (46.1 vs 65.6%, P = 0.034). These findings indicate that while a polyclonal population of T cells is present in RA synovium, the predominant patterns of TCR transcript expression may be somewhat more restricted, suggesting that TCR-based therapy of RA is possible.

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.

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.

Phenotypic characterization of 3H-thymidine incorporating cells in rheumatoid arthritis synovial membrane

Tritiated-thymidine incorporating cells in synovial tissue samples from ten patients with definite or classic rheumatoid arthritis (RA) were studied by combining two techniques. Tritiated-thymidine-labelled cells were seen in autoradiography and simultaneously the subtype of them was determined with immunoperoxidase staining using monoclonal antibodies. Tritiated-thymidine-labelled cells comprised 0.8 +/- 0.4% of all the inflammatory cells in RA synovial membrane. Of all 3H-thymidine-labelled cells 34 +/- 17% were positive for OKT8 and 19 +/- 8% for OKT4 monoclonal antibodies. OKM1-positive cells comprised 7 +/- 3% of all 3H-thymidine labelled cells, whereas only a few (3 +/- 4%) of them were positive for pan-B monoclonal antibody. This study emphasizes the importance of activated OKT8 lymphocytes in RA synovial membrane.

Functional capacities of T lymphocyte subsets from synovial fluid and blood in rheumatoid arthritis

A reverse haemolytic plaque forming cell (PFC) assay was employed to analyse the impact of T suppressor/cytotoxic and T helper cells on B cell function in 10 patients with rheumatoid arthritis (RA). In all cases T8-enriched cells from synovial fluid and blood suppressed the pokeweed mitogen (PWM) induced IgM, IgG, and IgA secretion by autologous lymphocytes to the same degree. The suppression was partly abolished by irradiation of T8-enriched cells. T4-enriched cells from blood increased the PWM induced Ig secretion by autologous blood B cells. In six of 10 patients responses 1.2 to four times higher were obtained with T4-enriched cells from synovial fluid, but in four of 10 patients synovial fluid T4-enriched cells did not increase the PWM responses of blood B cells. T4- and T8-enriched T cells from synovial fluid comprised more Ia+ cells than did T cells from blood (36% v 3% and 43% v 6%). Ia+ T helper and suppressor/cytotoxic cells may modulate in vivo activation of synovial B cells in RA.

T lymphocyte lines from arthritic synovial fluid: establishment and function

T lymphocyte lines have been established, with the addition of interleukin-2 (IL-2), from the synovial fluid (SF) of patients with arthritis. Characterisation of seven of these SF-derived T cell lines showed them to be T3+, T11+, and to contain a significant proportion of T8+ cells (mean 41%). The proportion of T4+ cells varied among the lines, with a mean T4+/T8+ ratio of 0.6. A significant autologous mixed lymphocyte reaction (AMLR) was observed only in one of four T cell lines assayed. Two of four lines assayed showed natural killer (NK) cell-like activity, while one line displayed a significant suppressor activity, suggesting that the T cell population in SF contained NK-like cells or suppressor cells, or both, either of which may be selected in the establishment of SF-derived T cell lines.