Characterization of in vivo activated lymphocytes found in the peripheral blood of patients undergoing cardiac operation.

We studied in vivo lymphocyte activation in patients who underwent cardiac operation. A large number of deoxyribonucleic acid-synthesizing cells characterized by 3H-thymidine uptake and morphologically atypical lymphocytes were found after operation in the peripheral blood samples of patients, the peak level occurring on the sixth or seventh postoperative day. Most of the deoxyribonucleic acid-synthesizing cells were in the B cell fraction. The number of antibody secreting cells in the patients' peripheral blood samples was found increased from the normal level after operation. Immunoglobulin A-secreting cells were the most elevated fraction. The percentage of helper (OKT4) and suppressor (OKT8) cells in the postoperative samples was not significantly different from that in the preoperative samples. Only a few were Ia antigen positive cells. Co-culture of patients' B cells with their own T cells and with the T cells taken from two healthy controls revealed no signs of any helper or suppressor effect on these antibody-secreting cells. The results show that after cardiac operation the peripheral blood of patients contains an increased number of immunoglobulin secreting cells. The regulatory T-lymphocytes seem not to have any effect in vitro on these in vivo activated cells.