Pokeweed mitogen activated suppressor T-cells preferentially reduce immunoglobulin secretion by differentiated B-lymphocytes.

In contrast to pokeweed mitogen (PWM), S. aureus Cowan I (SAC) does not activate suppressor T-cells in cultures of human peripheral blood mononuclear cells, although the SAC induced response leading to the appearance of immunoglobulin secreting cells (ISC) is suppressed by PWM activated suppressor T-cells. Therefore, cultures co-stimulated by SAC and PWM were chosen to find out which stage of the SAC triggered B-cell response is controlled by PWM activated suppressor T-cells. By incorporation of [3H]thymidine and determination of B-cell number in culture it was shown that neither PWM itself nor PWM induced suppressor T-cells interfere with SAC induced B-cell proliferation. The final stages of B-cell maturation were monitored by parallel evaluation of cells producing immunoglobulins (cells with intracytoplasmic immunoglobulins) and secreting them (plaque assay). It was shown that PWM activated suppressor T-cells reduce the number of ISC more effectively than the number of immunoglobulin producing cells, indicating that these two features of differentiated B-lymphocytes may be independently controlled.