Circulating T and B lymphocytes in progressive systemic sclerosis.

Thymus derived (T) and bone-marrow derived (B) lymphocytes were quantitated in 11 untreated patients with progressive systemic sclerosis (PSS) and in 11 age and sex matched controls. T and B lymphocytes were identified according to their receptor sites for sheep red blood cells and activated complement, respectively. All patients had a normal lymphocyte count. The mean per cent value of circulating T lymphocytes was less in PSS patients (38 per cent) as compared with controls (56 per cent) (P less than 0.005), while no significant difference existed for the circulating B lymphocytes (PSS 14 per cent; controls 11 per cent). The mitogenic response to phytohemagglutinin (PHA) was assessed by comparing dose response curves in PSS with those obtained from matched controls. No significant difference could be detected between these groups.