Immunologic effects of interferon-α in man: Treatment with human recombinant interferon-α suppresses in vitro immunoglobulin production in patients with chronic type B hepatitis

The effect of human recombinant interferon-α on lymphocyte proliferation and differentiation was studied in 18 patients with chronic type B hepatitis who were participating in a randomized controlled trial of interferon-α therapy. Peripheral blood mononuclear cells (PBMC) were obtained by lymphopheresis before and during a 4 mo course of interferon. Pokeweed mitogen-induced immunoglobulin synthesis by PBMC obtained from patients before therapy was similar to that of PBMC from normal individuals. However, after 2 wk treatment with human recombinant interferon-α mitogen-induced immunoglobulin production was decreased by an average of 50%. Staining for cytoplasmic immunoglobulin revealed decreases that paralleled secreted immunoglobulin, indicating that interferon-α treatment inhibited immunoglobulin synthesis. Mixing autologous T and B cell enriched populations from before and during interferon treatment revealed that the decrease in immunoglobulin synthesis involved a defect in the B cell-enriched population. In contrast to immunoglobulin synthesis, pokeweed mitogen-induced lymphocyte proliferation was not significantly affected by in vivo administration of interferon-α. Thus a major effect of in vivo interferon-α on immunoregulation in patients with chronic type B hepatitis appears to be an inhibition of the late stages of B cell differentiation into immunoglobulin producing and secreting plasma cells.