Summary The hypothesis that T‐cell responses to the 60 000 MW family of heat‐shock proteins (hsp) may be related to the severity of rheumatoid arthritis (RA) was examined. Peripheral blood mononuclear cells (PBMC) from most normal individuals and both early and established RA patients proliferated in vitro in response to human hsp 60 and mycobacterial hsp 65 as well as tetanus toxoid (TT) and mycobacterial purified protein derivative (PPD). PBMC from some patients with established RA gave responses to hsp 60 that were above the normal range and/or peaked earlier than PBMC from normal individuals. The responses of PBMC from established RA to hsp 65, but not PPD or TT, were also higher than those from normal individuals, but the peak responses to all three antigens appeared delayed. Thus a selective increase in responsiveness to hsp 60 develops with disease duration in many RA patients. Six assessments of disease activity and severity were made but apart from rheumatoid factor titre, they were unrelated to the proliferative response. Similarly, disease activity and severity did not differ between those RA patients whose hsp 60 stimulated cells produced interferon‐γ and those who did not, although patients whose hsp 60‐stimulated T cells produced interleukin‐4 (IL‐4) and/or IL‐10, appeared to have less disease activity and severity than those who did not. Significant negative correlations were found between IL‐10 production by hsp 60‐stimulated cells and disease assessments. It is considered that RA is less severe in those patients whose hsp 60‐stimulated cells produce T‐helper 2 type cytokines.

SUMMARYIn order to determine the phenotype of the cells required for thyroid autoantibody production, peripheral blood mononuclear cells (PBMC) from patients with autoimmune thyroid disease (AITD) were transferred to severe combined immunodeficient (SCID) mice. The production of human IgG, thyroglobulin (Tg) antibody and thyroid peroxidase (TPO) antibody in the SCID recipients was monitored for up to 4 months. PBMC from 10 of 13 AITD patients produced substantial IgG (> 100 jug/ml) and detectable Tg and TPO antibodies in recipient mice. PBMC pretreated to deplete or enrich T cells produced low or undetectable thyroid-specific antibody in SCID mice. Depletion of CD4+ T cells resulted in much lower or undetectable IgG, Tg and TPO antibodies compared with levels seen in recipients of control PBMC. By contrast, depletion of CD8+ T cells from the PBMC had no overall effect on autoantibody production, although with PBMC from some patients CD8+ depletion possibly enhanced both IgG and autoantibody production. In eight of 10 experiments, autoantibody levels reached maximal titres before total IgG levels peaked. It is considered that thyroid autoantibodies are produced from memory B cells activated in SCID mice and that this activation is T cell-and CD4+ T cell-dependent.

SUMMARYWe have studied the ability of lymphocytes from the blood, thyroid and lymph nodcsof patients with autoimmune thyroid disease (AITD) to produce aiitoantibodies to thyroglobulin (Tg) and/or thyroid peroxidase (TPO) in SCID mice. Human IgG class Tg and/or TPO antibodies were delectable in plasma from SCiD mice 7 days after transfer of 15-25 x 10'' cells/moiise and ihc highest levels were recorded 2-3 weeks later. In contrast. Tg and/or TPO antibodies were undetcctable in recipients of lymphocytes from thyroid antibody negative controls. AITD thyroid lymphocytes produced the mosi antibody in recipient mice and lower levels were observed in recipients of AITD blood and lymph node lymphocytes. The amounls of Tg and/or TPO tmtibody detected were in accordance with the ability of Ihyroid and lymph node lymphocytes to secrete these autoanlibodies spontaneously in culture (indicating ihc presence of cells activated in the patient) and with the capacity of blood lymphocytes (probably B memory cells) to secrete Tgand/or TPO antibodies in ctilture in response to pokeweed mitogen. Tg antibodies in plasma from SCID recipients of thyroid lymphocytes were of subclasses IgGl. IgG2and !gG4and the proportions closely resembled those of the donor's serum Tg antibodies. Blood lymphocytes transferred to SCID recipients were also able to produce Tg antibodies of subclasses 1. 2 and 4 but the subclass distribution varied between mice and the reason for this is not clear at present. Since SCID mice provide an environment in which B lymphocytes from paiients with AITD can be activated without mitogen to secrete thyroid antibodies, this model will provide a powerful system for elucidating the mechanisms regulating the secretion of hutiian antibodies to Tg and TPO-

We have studied the ability of mononuclear cells extracted from the colon (CMC), draining lymph nodes (LNMC), peripheral blood (PBMC) and spleen (SMC) of a patient with ulcerative colitis and severe autoimmune haemolytic anemia to produce red cell autoantibodies. The LNMC, PBMC and SMC secreted immunoglobulin in vitro in pokeweed mitogen culture but not spontaneously. They also produced immunoglobulin when transferred to severe combined immunodeficient (SCID) mice but no anti-red cell activity was demonstrable. In contrast, in vitro cultures of CMC produced immunoglobulin spontaneously, showing the presence of activated B-cells and plasma cells, but anti-red cell activity could not be demonstrated. However, CMC transferred to SCID mice were able to produce IgG with anti-red cell activity. These results concur with clinical observations suggesting that the colon is the source of red cell autoantibodies in these patients.

The ability of T cells from rheumatoid factor (RF)-positive patients with rheumatoid arthritis (RA) to respond to immunoglobulin G (IgG) was assessed. Peripheral blood mononuclear cells (PBMC) from RA patients and normal individuals were cultured with and without human IgG or Mycobacterium tuberculosis-purified protein derivative (PPD) for 7 days and their proliferative response measured at intervals by their ability to take up tritiated thymidine. PBMC from 14/26 RA patients proliferated in response to IgG (taking a stimulation index of 3 or above as positive). The peak response varied between individuals but usually occurred on day 5, the same day, or 1 day later than the peak response to PPD. By contrast, PBMC from a significantly lower proportion (1/9) of normal individuals and patients with other arthritides (0/6) responded to IgG, although all responded to PPD. PBMC from 9/14 RA patients responded to Fab fragments of IgG but only 3/9 to the Fc fragment. Higher proliferative responses from RA PBMC were elicited by IgG aggregates than the original IgG preparation, but PMBC from 5/5 normal individuals and 5/6 patients with other arthritides failed to respond to the aggregates. The response to IgG was human leucocyte antigen (HLA)-DR restricted and mediated by CD4+ T cells. It is considered that these results advance the hypothesis that IgG-reactive T cells contribute to the initiation or perpetuation of RA.