A prospective study of the clinical utility of lymphocyte monitoring in the cardiac transplant recipient.

Monitoring peripheral lymphocytes for changes in antigen expression or subpopulations was performed by flow cytometry in an attempt to identify infection or rejection in cardiac transplantation recipients (CTRs). In this study, 32 cardiac transplantation recipients were followed prospectively, and the results of 274 lymphocyte analyses for transferrin receptor expression, an indicator of lymphocyte activation, and CD4/CD8 lymphocyte ratios were correlated with the patient's clinical status, e.g., infection (early or late), rejection (mild, moderate, or severe), or quiescence. The percentage of lymphocytes expressing the transferrin receptor (%TR+) increased significantly during all stages of infection (2.9%, P = 0.02), or stratified into early (2.7%, P = 0.03) or late stage infection (2.6%, P = 0.03). The increase in %TR+ lymphocytes was also noted during mild (2.8%, P = 0.01) and moderate (3.0%, P = 0.008) rejection. The specificity and positive predictive value of an increased %TR+ lymphocyte was 97% and 93%, respectively, during early infection; 92 and 71%, respectively, during mild rejection; and 85 and 80%, respectively, during moderate rejection. The CD4/CD8 lymphocyte ratio did not correlate with either infection or rejection (P greater than 0.05). In conclusion, an increase in the %TR+ lymphocytes indicates the presence of infection, especially acute infection, or, less likely, rejection in the cardiac transplant recipient, but its clinical utility may be as a screening test for the presence of infection, especially early infection in CTRs during the posttransplantation period. The CD4/CD8 lymphocyte ratio does not correlate with the presence of infection or rejection in the CTR.