Polyfunctional analysis of human cytomegalovirus (HCMV)-specific CD4(+) and CD8 (+) memory T-cells in HCMV-seropositive healthy subjects following different stimuli.

Abstract

Following primary human cytomegalovirus (HCMV) infection, both humoral and T-cell-mediated immune responses develop in immunocompetent subjects. However, while antibodies may be measured by different methodologies, the T-cell-mediated response remains to be analyzed in its polyfunctional aspects, in view of defining (following different stimuli) the optimal assay to monitor the HCMV-specific T-cell response in HCMV-seropositive subjects. In a group of 30 HCMV-seropositive adults, T-cell response revealed by the HCMV-infected dendritic cell (iDC) stimulus was compared with those given by the HCMV-infected cell lysate (iCL), and by a 34-peptide pool (PP). All HCMV-seropositive subjects showed presence of both HCMV-specific CD4(+) and CD8(+) T-cells in peripheral blood following iDC stimulation. One subject did not respond to PP. As compared to iDC, the number of HCMV-specific stimulated T-cells/μl blood was slightly lower for iCL (P = 0.195) and significantly lower for PP (P = 0.001). Polyfunctional analysis of the T-cell response indicated that the lower number of CD4(+) T-cells stimulated by iCL was due to the bifunctional (IFN-γ(+) TNF-α(+)) and CD40L-negative T-cell reduction, while the reduction in specific PP-stimulated CD8(+) T-cells was attributable to the reduction in tri-(IFN-γ(+) TNF-α(+) IL2(+)), bi-(IFN-γ(+) TNF-α(+)) and mono-(IFN-γ(+)) functional T-cells. In addition, 15/30 (50%) subjects showed a CD4(+) cross-response to PP, and 11/30 (37%) a CD8(+) cross-response to iCL. HCMV-specific stimulus given by iDC is not significantly different from that of iCL on CD4(+) and is significantly superior to that of PP on CD8+ T-cells. However, iCL may contribute significantly to CD8(+), and PP to CD4(+) T-cell stimulation.