A rapid manual method for CD4+ T-cell quantitation for use in developing countries

Objective: To evaluate a manual method (Cytosphere) for quantifying CD4+ T-cell numbers. Design: Cross-sectional study of HIV-1-seronegative and HIV-1-seropositive individuals evaluated for absolute CD4 counts by both standardized flow cytometric measurements and manual Cytosphere technology using a hemacytometer. Setting: University research hospitals in both the United States and Africa. Patients, participants: Blood specimens from 382 patients were evaluated. These were broken down into 294 samples obtained from HIV-1-seropositive patients and 88 samples obtained from HIV-1-seronegative patients. Interventions: None. Outcome measured: Absolute CD4 cell number. Results: Evaluation of samples obtained from HIV-1 patients in both the United States and Africa demonstrated an overall correlation of the Cytosphere assay with flow cytometry of 0.912 (95% confidence interval, 0.895-0.928; P<0.001). When samples were stratified based on CD4+ T-cell counts determined by flow cytometry, the Cytosphere assay had a 96% predictive value for correctly identifying individuals with CD4 T-cell counts >200×10⁶/l and a 92% predictive value for correctly identifying individuals with CD4 T-cell counts <200×10⁶/l. Conclusions: This assay appears to have the potential for the quantitation of CD4 cells in the limited laboratory facilities in developing countries and to have a strong correlation with standard flow cytometric technology.