Erythrocyte rosette inhibition as an assay for naturally occurring T lymphocytotoxic antibody in systemic lupus erythematosus.

By means of a modified sheep erythrocyte rosette inhibition assay, we were able to detect naturally occurring lymphocytotoxic antibodies in sera from patients with systemic lupus erythematosus (SLE). The incidence of lymphocytotoxic antibodies was 86% in all SLE patients, and 100% in patients with active disease. Since this assay detects only the antibodies that react with the determinants on T cells or on both T and B cells, it has a great advantage of demonstrating in combination with appropriate absorptions the antibodies specific for T cells. When an appropriate panel of target cells was used, most of the antibodies in SLE sera as detected by this assay appeared to be analogous to a natural thymocytotoxic autoantibody (NTA) of New Zealand mice in its specificity and nature. The changes in the antibody titer of a patient with SLE during the course of disease correlated well with those in the total number of T cells in the blood, the antinuclear antibody titer, and some delayed skin hypersensitivities.