Association of helper activity for B-lymphocyte differentiation with lymphocytes having both SRBC and complement receptors in a patient with lymphoproliferative disease

Approximately 96% of the lymphocytes of a patient with lymphocytic leukemia were found to possess surface membrane complement receptors, showed T-lymphocyte antigen, and formed spontaneous rosettes with sheep erythrocytes (SRBC). These cells showed the morphology of small- to medium-size lymphocytes and lymphoblasts. A lymphocyte transformation study showed that these T lymphocytes with complement receptors gave no response to phytohemagglutinin-P or concanavalin A and a low response to pokeweed mitogen (PWM) stimulation. No production of anti-SRBC antibody was detected with these lymphocytes as determined by a plaque assay after the lymphocytes had been stimulated by PWM. Using this plaque assay, these lymphocytes were cocultured with normal lymphocytes to test for their influence on normal antibody production. It was shown that the T lymphocytes with complement receptors were capable of providing helper activity for B-lymphocyte differentiation.