Antibody Synthesis by Bone Marrow

As bstract. Normal volunteers received either initial or booster immunization with tetanus toxoid. Bone marrow and peripheral blood mononuclear cells were obtained for up to 28 d after immunization and were analyzed for synthesis of total Ig and specific antibodies to tetanus toxoid. Cells were cultured in vitro for 3 or 7 d with or without pokeweed mitogen (PWM). Synthesis of IgG and IgM antibodies to tetanus (IgG-Tet and IgMTet) and total IgG and IgM was determined by radioimmunoassay. Four functional B cell subpopulations were detected in the bone marrow after booster tetanus immunization: (a) B cells that spontaneously synthesized IgG-Tet appeared on day 7 after immunization but were undetectable by day 21; (b) B cells that synthesized IgGTet after stimulation with PWM appeared after day 21 and persisted for greater than 1 mo; (c) B cells that synthesized IgM-Tet in the presence ofPWM were detectable before and after immunization; and (d) B cells that spontaneously synthesized IgM-Tet appeared on day 7 and were undetectable by day 21. In contrast to the other three types of bone marrow B cells described, this fourth subpopulation of PWM-independent IgM-Tet-synthesizing B cells was not detected in the peripheral blood. After primary immunization, no spontaneous antibody-producing cells were detected in the blood or bone marrow, although there was a small rise in IgM-Tet in two ofthree