Human tonsil B lymphocyte function. I. The proliferative response to Staphylococcus aureus and pokeweed mitogen in relation to surface heavy chains mu and delta.

Human tonsil non-T cells were separated into surface IgD positive (sIgD+), surface IgD negative (sIgD-), sIgM+ and sIgM- fractions by rosetting and gradient centrifugation with ox red blood cells, coated with immunosorbent purified goat anti-human heavy chain antibodies. No activation or suppression was found as a result of the separation technique. The sIg patterns of the isolated B cell fractions showed the effectiveness of the separations; sIgD+ and sIgM+ fractions were to a great extent overlapping populations, but there was a definite population of s mu + delta- cells (about 20% of the sIgD- fraction). The isolated fractions were tested for proliferative responses to Staphylococcus aureus (Sta) and pokeweed mitogen (PWM). The sIgM+ fraction showed the best response to Sta, eight times better than the sIgM- fraction, while the sIgD+ and sIgD- fraction showed equal responses to Sta. The sIgM- fraction responded best to PWM but all fractions responded quite well. Our results indicate that PWM is a mitogen to a whole variety of rather mature B cells while the Sta target B cell is restricted to the relatively immature sIgM+D- and sIgM+D+ cells.