Cytomegalovirus infection in cardiac transplant recipients associated with chronic T cell subset ratio inversion with expansion of a Leu-7+ TS-C+ subset.

Lymphocyte subsets were analysed in 18 patients during the first 3 years after cardiac transplantation. The patients received Cyclosporin A and prednisolone for maintenance immunosuppression. Serological evidence of active cytomegalovirus (CMV) infection was found in 13 cases (72%), and in 12 of these an inversion usually of the T helper/T suppressor-cytotoxic ratio (TH/TS-C) was detected. T subset inversion usually preceded the diagnostic rise in CMV antibody titre. In 69% of patients with CMV the TH/TS-C ratio remained inverted throughout follow-up (245-951 days). Persistent T subset inversion was not found in all five patients who lacked serological evidence of active CMV. Chronic inversion consisted of an average increase in TS-C of 152% and an average decline in TH cells of 31% as compared to CMV negative patients. The proportion of lymphoid cells reacting with a phenotypic marker for natural killer (NK) cells (Leu-7) was increased by 83%. These alterations were also reflected in the absolute numbers of cells with these markers. Two-colour immunofluorescence analysis revealed that the expanded TS-C population present during chronic inversion was predominantly Leu-7+. As TS-C+ Leu-7+ cells in healthy persons may be hyporesponsive NK cells, a sustained increase in this cell type in allograft recipients could further reduce immunocompetence, thereby predisposing to superinfection or malignancy.