702 EVIDENCE FOR EXCESSIVE T SUPPRESSOR CELL ACTIVITY IN X-LINKED IMMUNODEFICIENCY WITH HYPER-IgM

Abstract

Increased T suppressor cell activity has been detected in patients with common variable hypogammaglobulinemia. In the present study, we used both a plaque-forming cell (PFC) assay that detects cells producing IgM antibody to sheep red blood cells (SRBC) and a double antibody radioimmunoassay to measure IgM synthesized by mononuclear blood cells in evaluating two patients with x-linked immunodeficiency with hyper IgM (HypM). Cultures from 18 normal individuals gave a range of 180-2,254 PFC/106 viable cells, and co-cultures of cells from pairs of normals averaged 83% of the PFC's predicted from individual culture data. The two HypM patients failed to produce PFC to SRBC, and co-cultures of HypM and normal mononuclear cells showed complete suppression of PFC activity by the normal cells. The HypM patients cells were capable of synthesizing IgM following pokeweed mitogen stimulation but suppressed IgM synthesis by normal cells in co-culture. In patient DM, the nature of the suppressor cell was investigated by co-culturing lymphocyte subpopulations and by adding hydrocortisone (HC). The following data were obtained: The findings indicate that patients with this defect have excessive numbers of hydrocortisone-sensitive T cells that can suppress IgM synthesis by normal B cells and suggest that these cells develop secondary to the patients' excessive IgM production.