CELL SUPPRESSION IN PPD-INDUCED BLAST SPECIFIC RESPONSE OF HUMAN PERIPHERAL-BLOOD LYMPHOCYTES

Abstract

Specific stimulation of T[thymus-derived]-cells by PPD [purified protein derivative] was inhibited by their autologous B [bone marrow-derived] cells. This inhibition was obtained with B cells separated by depletion of E-RFC [sheep erythrocyte rosette-forming cells] or by elution with human IgG [immunoglobulin G] of lymphocytes bound to Sephadex beads coated with rabbit anti-human Fab fragment antibody. The suppression was proportional to the number of B cells added to 106 T cells incubated with PPD. As previously reported, the suppression was more marked in the case of B or T cells from BCG-vaccinated subjects with negative skin tests. The suppressive phenomenon required viable B cells, and was inhibited by cycloheximide, but was not altered by pretreatment of suppressor cells with actinomycin D or colchicine. B-suppressor cells probably interfere with recognition of PPD by T cells rather than with the proliferative phase of the specific blast response. Using various surface markers (i.e., Ig, C3 [the 3rd complement component] and Fc receptors) it was shown that the suppressor cells represent a subset of Ig-bearing B cells which do not carry Fc receptors.