Impaired B lymphocyte function during open heart surgery

: Sequential in vitro lymphocyte function tests in 13 patients undergoing cardiac operation were performed to study B lymphocyte function following operation. Lymphocytes were stimulated with phytohemagglutinin (PHA), pokeweed mitogen (PWM) and Staphylococcus aureus Cowan 1 (SAC). Mitogen responses were measured by 3H-labeled thymidine incorporation. The SAC responses were significantly depressed following operation. Immunoglobulin secreting cells were measured by protein A plaque forming cell assay. The numbers of immunoglobulin secreting cells induced by PWM or SAC decreased remarkably at least as long as 3 day after the operation. The percentage of circulating B lymphocytes increased significantly postoperatively. This indicates that the B lymphocytes remaining after the operation were functionally impaired.