Characteristics of histamine receptors present on suppressor T cells in "healthy individuals".

Twelve to 30% histamine receptor bearing cells were detectable in the peripheral blood mononuclear cells of healthy tuberculin sensitive individuals. The number of binding sites per cell ranged from 2.1 X 10(4) to 5.08 X 10(4) (mean 2.5 X 10(4)) with an affinity ranging from 2.5 X 10(-6) M to 10.9 X 10(-6) M (mean 3.6 X 10(-6) M). The histamine receptors on these cells were found to be of H2 type as indicated by the abrogation of binding of 3H-histamine by cimetidine. It was further confirmed that histamine receptor bearing cells in the peripheral blood belonged to a T cell subset which formed rosettes with AET treated sheep erythrocytes and had receptors for Fc portion of IgG and phenotype markers of T3 and T8. Deletion of such cells by means of affinity chromatography on histamine bound Sepharose columns, led to enhanced antigen induced lymphoproliferation indicating the suppressor nature of these T cells.