Monitoring of human cytomegalovirus (HCMV)-specific CD4+ T cell frequency by cytokine flow cytometry as a possible indicator for discontinuation of HCMV secondary prophylaxis in HAART-treated AIDS patients

Objective: Absolute CD4⁺ T cell count and human cytomegalovirus (HCMV)-specific CD4⁺ T cell frequency (as determined by cytokine flow cytometry, CFC) were compared for their ability to predict HCMV disease and safe discontinuation of HCMV secondary prophylaxis. Study design: Three groups of AIDS patients with previous nadir CD4⁺ T cell count + T cell count (group C). Results: During follow-up, while some patients showed a stable HCMV-specific CD4⁺ T cell response, others had a fluctuating response (unstable responders) or showed no response at all. In detail, 13/48 group A patients were either HCMV non-responders or unstable responders and 2 of them developed HCMV viremia; 3/11 group B patients were unstable responders, none developing either HCMV viremia or disease; finally, 9 group C patients discontinued HCMV prophylaxis based on absolute CD4⁺ T cell count >150cells/μl, but in 2 of them lacking HCMV-specific response HCMV retinitis relapsed. None of the seven group C patients discontinuing HCMV prophylaxis on the basis of CFC showed HCMV disease relapse. Conclusions: CFC may support absolute CD4⁺ T cell count for both guiding HCMV prophylaxis discontinuation and better monitoring HCMV infection in AIDS patients with no previous HCMV disease or having discontinued HCMV prophylaxis.