HUMAN NONSPECIFIC SUPPRESSOR FACTOR (HNSF) - CELL SOURCE AND EFFECTS ON T-LYMPHOCYTES AND B-LYMPHOCYTES

The human nonspecific suppressor factor (hNSF), the probable counterpa rt of the murine monoclonal nonspecific suppressor factor (MNSF), has been isolated from the ascitic fluid of a patient with systemic lupus erythematosus and characterized. hNSF presents an inhibitory activity on the proliferation and IgG production of mitogen stimulated human PB MC. In the present study, we demonstrate that hNSF can be isolated fro m the supernatants of Con A-activated T cells, but not from CD8-deplet ed T cells, indicating the CD8(+) T cells are the major source of the factor. We also studied the effects of hNSF on purified human B and T cells; hNSF strongly inhibited the proliferation and Ig secretion by h ighly purified B cells induced by SAC plus IL-2, as well as the prolif eration of T cells activated by ConA plus IL-2. These results indicate that hNSF is a CD8(+) T cell product with strong antigen-nonspecific immunoregulatory action on both lymphocyte populations.