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T cell subpopulations were assessed by two colour flow cytometry with phycoerythrin conjugated anti-CD45RA and anti-CD29 and fluorescein conjugated anti-CD4 and anti-CD8 monoclonal antibodies, on peripheral blood lymphocytes from 12 patients with systemic sclerosis and from nine control subjects. The percentage of CD4+CD29+ cells was significantly higher in patients with systemic sclerosis than in controls (mean (SEM) 68.8 (3.1) v 47.9 (4.1) respectively). CD4+CD45RA+ cells were not significantly different in patients and controls. CD8+CD29+ and CD8+CD45RA+ subpopulations were significantly higher in patients with systemic sclerosis than in controls (83.0 (3.2) v 58.7 (6.8) and 80.2 (3.0) v 66.9 (3.2) respectively). The increase in the percentage of CD29+ cells suggests an activation of memory cells in patients with systemic sclerosis, which may play an important part in the pathogenesis of the disease.

Several immunoregulatory defects of Epstein-Barr virus (EBV) induced B cell activation have been described in patients with rheumatoid arthritis (RA), suggesting that EBV may have a role in the pathogenesis of RA. We assessed EBV specific T cell regulation in 20 patients with progressive systemic sclerosis (PSS) and immune to EBV and in 10 control subjects also immune to EBV by comparing the secretion of IgM into supernatants of 16 day cultures of B cells alone and cocultures of B and autologous T cells. In control subjects autologous T cells mediated a significant decrease in the secretion of IgM by B cells at 12 and 16 days of culture. Analysis of individual responses showed the existence of two subgroups of patients with PSS: group I (10 patients) had a suppressor T cell function similar to that of controls; group II (10 patients) had a defective T cell function. Differences in the duration or severity of the disease, the slow acting therapeutic agents, and anti-inflammatory drugs could not account for these subdivisions. These results suggest that several immunoregulatory defects of EBV induced B cell activation exist in different connective tissue diseases.