Flow cytometric analysis of cytomegalovirus-specific cell-mediated immunity in the congenital infection.

Flow cytometric analysis of CD4(+) and CD8(+) T cells specific to human cytomegalovirus (CMV) was undertaken in seven patients with congenital CMV infection, six healthy infants who had acquired infection, and six CMV-seropositive adults. Intracellular cytokine assays showed that 0.03-2.23% of CD4(+) T cells in the healthy infants and adults produced interferon-gamma (IFN-gamma) in response to CMV antigens. In contrast, such CD4(+) T cells were almost undetectable in patients with congenital CMV infection who were younger than 2 years of age. Tetrameric major histocompatibility complex/peptide complex analysis demonstrated HLA*A2402-restricted phosphoprotein 65-specific CD8(+) T cells to be present in most healthy infants and adults tested, but almost absent in the patients. Interestingly, CMV-specific CD4(+) T-cell responses were observed in two patients with congenital infection beyond the age of 5 years. The present study points to impairment of CMV-specific cellular immunity in patients in single-cell levels with congenital CMV infection during the infant period and possible restoration in later childhood.