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

Abstract

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 2.5 × 10^-6 M to 10.9 × 10^-6 M from 2.1 × 10⁴ to 5.08 × 10⁴ (mean 2.5 × 10⁴) with an affinity ranging from (mean 3.6 × 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.