Human Cytomegalovirus Specific CD8+ T Lymphocytes Display Interferon-γ 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)-γ secreting CD8+ T cells was determined using intracellular INF-γ staining after NLVPMVATV pulsing in vitro. The proportion of IFN-γ secreting pentamer-stained CD8+ T cells was calculated, representing the capacity for INF-γ secretion among HCMV-specific CD8+ T cells. We observed that the frequency of HCMV-specific pentamer-stained CD8+ T cells and HCMV-specific IFN-γ secreting CD8+ T cells both remained unchanged, yet the proportion of IFN-γ 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-γ 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.