Activated T lymphocytes in the peripheral blood of patients with systemic lupus erythematosus induce B cells to produce immunoglobulin.

Systemic lupus erythematosus (SLE) is characterized by multiple T and B cell abnormalities. This study was designed to investigate the cell surface membrane characteristics of T cells by using single and double immunofluorescence and examine the role of HLA-DR+ T cells in the production of immunoglobulin by B cells. The results presented: (a) confirm the presence of a larger population of T-cells bearing DR antigens in patients with SLE than in normal controls, (b) demonstrate that DR positive cells are equally distributed in helper/inducer and suppressor/cytotoxic subsets of lymphocytes from patients with SLE, (c) show no elevation in the percentage of T cells bearing interleukin 2 (IL-2) receptors, (d) demonstrate that DR positive, but not DR negative T-cells, multiply in the presence of conditioned media and, (e) demonstrate that DR positive T cells provide helper factors which enhance the production of immunoglobulin by B cells. We propose that T-cells bearing DR antigens in patients with SLE are functional in vivo, and may be responsible for the B cell overactivity.