A RAPID AND RELIABLE ASSAY TO ENUMERATE CD4(-LYMPHOCYTES IN WHOLE-BLOOD() T)

We compared the performance of a rapid and simple anti-CD4 antibody-co ated microsphere assay with flow cytometry and immunofluorescence for quantitation of absolute count of CD4(+) T lymphocytes. A longitudinal evaluation of CD4(+) T lymphocytes by flow cytometry and microsphere assay in 10 human immunodeficiency virus (HIV)-seronegative and 59 HIV -seropositive individuals was conducted over a period of 9 months. Sta ndard flow cytometry analysis was performed to establish the absolute CD4(+) T-lymphocyte count. The microsphere assay uses whole blood; CD1 4(+) and CD4(+) cells are first blocked by small latex beads coated wi th anti-CD14 antibody, and remaining cells are stained with larger ant i-CD4 antibody-coated beads. Cells rosetted with only anti-CD4 antibod y-coated beads are counted with use of a hemacytometer. Immunofluoresc ence microscopy was performed by standard techniques with use of perip heral blood mononuclear cells. The predictive value for stratification of HIV-seropositive patients by CD4(+) T-lymphocyte values of <200/mu l was 95% when the microsphere method was compared with flow cytometr y. A correlation coefficient of 0.91 between the two assay methods was demonstrated in 281 CD4(+) T-lymphocyte tests for absolute count. Fin ally, the flow cytometry method yielded better results than did the mi crosphere assay and immunofluorescence microscopy, in descending order of accuracy. The microsphere method should be effective in determinin g absolute CD4(+) T-lymphocyte count in developing countries where, fo r a variety of reasons, no other method can be reliably performed.