KINETICS OF IMMUNOGLOBULIN-SYNTHESIS AND SECRETION BY RESTING AND POKEWEED MITOGEN-TRANSFORMED HUMAN LYMPHOCYTES

The kinetics of immunoglobulin (Ig) synthesis and secretion were examined in human plasma cells, resting lymphocytes and pokeweed mitogen (PWM)-transformed lymphocytes to define the Ig production properties of the PWM-transformed lymphocyte which is often used as a model for the plasma cell. By pulse labeling with [3H]leucine, the time course of intracellular Ig synthesis was similar for lymphocytes and plasma cells. Plasma cells differed basically by exhibiting secretion of labeled Ig into the culture medium exceeding intracellular Ig levels after several hours of pulsing; resting lymphocytes were nonsecretory. PWM-transformed peripheral blood lymphocytes had a spectrum of morphologic differentiation from numerous large lymphoblasts to relatively few plasmacytoid cells. They had enhanced intracellular Ig synthesis (2.5-fold increase over baseline resting state) but no significant rise in secreted Ig, thus exhibiting enhanced Ig production but retaining a lymphocyte-like Ig kinetic profile. The PWM-transformed peripheral blood lymphocyte apparently represents only a partial differentiation toward the mature antibody-secreting plasma cell.