In vitro immunoglobulin production in mitogen-stimulated cultures of peripheral blood and bone marrow cells from young and old adults, and cases of benign monoclonal gammopathy.

Peripheral blood samples collected from normal individuals and patients with benign monoclonal gammopathy (BMG) were separated and assayed for their T-cell subpopulations, PHA blast formation as well as immunoglobulin (Ig) synthesis in vitro. Bone marrow cells of most the cases were also assayed for Ig synthesis. Age-related changes of T-cell subsets and PHA blast formation revealed a marked leveling off after the 8th decade. Comparing the age-related increase in Ig synthesis in peripheral blood lymphocytes, PWM-induced Ig synthesis of bone marrow cells was only slightly increased. The distribution of values for T-cell subsets, PHA blast formation and Ig synthesis in the BMG cases more closely resembled that in the aged than that in the age-matched controls. Immunoregulatory functions seem to be affected in BMG.