Immunologic monitoring of the cardiac transplant patient

Peripheral blood lymphocyte morphology and cell surface markers were repeatedly evaluated in 49 orthotopic cardiac transplant patients over a period of three years to determine the utility of these parameters in predicting an episode of acute cardiac rejection. Lymphocytes were measured with a calibrated microscope and termed "activated" if greater than 10 mu in diameter. If a patient demonstrated greater than 30 activated lymphocytes/cu mm, the same lymphocytes were stained with monoclonal antibodies directed to T-cell subsets and B cells. These findings were retrospectively correlated with endomyocardial biopsy results. Absolute numbers of T-cell subsets and B cells were analyzed via Student's t test to identify significant differences during acute cardiac rejection. Of 347 biopsy specimens, 47 demonstrated histologic features of acute cardiac rejection. Simultaneous immune activation of lymphocytes occurred with 33 of 47 samples, while another 51 episodes of lymphocyte activation were detected without acute rejection. No statistically significant differences in absolute numbers of T-lymphocyte subsets were noted at the time of acute rejection.