Human cytomegalovirus specific CD8(+) T lymphocytes display interferon-gamma secretion impairment in kidney transplant recipients with pp65 antigenemia.

Our study sought to investigate the immune response of cytotoxic T lymphocytes to human cytomegalovirus (HCMV) in kidney transplant recipients with virus reactivation. Nine kidney transplant recipients with serum HCMV immunoglobulin G and HLA-A 0201 genotype displayed HCMV pp65 antigenemia and were compared with 29 control recipients who were free of antigenemia. The frequency of total HCMV-specific cytotoxic T cells was determined using HLA-A2-NLVPMVATV-pentamer staining. The frequency of HCMV specific interferon (INF)-gamma secreting CD8(+) T cells was determined using intracellular INF-gamma staining after NLVPMVATV pulsing in vitro. The proportion of IFN-gamma secreting pentamer-stained CD8(+) T cells was calculated, representing the capacity for INF-gamma secretion among HCMV-specific CD8(+) T cells. We observed that the frequency of HCMV-specific pentamer-stained CD8(+) T cells and HCMV-specific IFN-gamma secreting CD8(+) T cells both remained unchanged, yet the proportion of IFN-gamma secreting CD8(+) T cells showed a significant difference between the 2 groups (39.2% +/- 17.2% vs 20.0% +/- 13.3% respectively; P = .004), reflecting impaired IFN-gamma secreting capacity of HCMV-specific CD8(+) T cells among kidney transplant recipients displaying antigenemia, which may be a crucial reason for HCMV reactivation in immunosuppressed patients.