Objective: To detect the human immunodeficiency virus 1 (HIV-1) p24 antigen in CD4(+);T cells by flow cytometry (FCM) and assess its application for auxiliary diagnosis of HIV-1 infection.

Methods: CD4(+);T cells from HIV-1-infected individuals and normal controls (negative controls) were detected for intracellular p24 antigen by FCM. Samples from early-HIV-infected individuals were collected, and the intracellular p24 antigen in CD4(+);T cells was detected by FCM. P24 antigen in plasma was detected by ELISA and nucleic acids were tested by nest-PCR. The results of these 3 assays were compared.

Results: The rates of p24(+);CD4(+);T cells of the infected individuals were significantly higher than those of the negative controls (P<0.01); the 95th percentile of p24(+);CD4(+);T cell rates of the infected individuals was 1.92% and the cutoff value was 2.00%. Infected individuals with CD4(+);T ≤350 cells/μL had higher p24(+);CD4(+);T cell rates than those with CD4(+);T >350 cells/μL (P<0.05). The detection of p24 antigen in CD4(+);T cells of early-HIV-1-infected patients could identify HIV-1 infection timely, and the detection efficiency of FCM was better than that of the ELISA of p24 antigen in plasma and was equal to that of nucleic acid testing.

Conclusion: The FCM detection of p24 antigen in CD4(+);T cells could be a promising auxiliary approach for the diagnosis of early HIV-1 infection.