Hypogammaglobulinaemia in systemic lupus erythematosus: report of a case with evidence for spontaneously activated T suppressor cells.
A patient with hypogammaglobulinaemia associated with systemic lupus erythematosus (SLE), a healthy HLA-A, B, C, D-identical and mixed lymphocyte culture (MLC)-negative sibling, and two mutually HLA-A, B, C, D-identical siblings were investigated. Blood mononuclear cells from the patient contained a high proportion of T lymphocytes with the suppressor/cytotoxic phenotype, and in vitro no development of Ig-secreting cells was observed in response to pokeweed mitogen (PWM) or to Epstein-Barr virus (EBV), as opposed to cell cultures from the siblings. In cell cultures from the two healthy HLA-identical siblings, T-lymphocytes as well as monocytes/macrophages (M phi's) could be replaced with corresponding cells from the sibling without major alterations of the pokeweed mitogen (PWM)-induced B cell response. In PWM-stimulated co-cultures of B cells from the patient with healthy HLA-identical T cells, moderate numbers of IgM-secreting cells developed, but not IgG- or IgA-secreting cells. T cells from the patient co-cultured with healthy HLA-identical B cells suppressed their Ig-secretion; this effect was abolished by irradiation of the T cells. The in vitro generation of T suppressor cells by concanavalin A (ConA) was normal. No evidence for abnormal suppressor function of monocytes/macrophages was obtained. Thus in this patient, spontaneously activated T suppressor cells as well as defective B cells were associated with hypogammaglobulinaemia.