Whole Blood Capcellia CD4/CD8 immunoassay for enumeration of CD4+ and CD8+ peripheral T lymphocytes

We evaluated the Whole Blood Capcellia(R) CD4/CD8, an immunoenzymatic method that provides absolute counts of CD4+ and CD8+ T cells in peripheral blood. The assay is based on the separation of T cells by use of an anti-CD2 magnetic bead suspension, followed by reaction of the CD4 or CD8 molecules with the corresponding monoclonal antibody coupled to peroxidase. CD4-positive monocytes were excluded from the assay. Freeze-dried magnetic bead-T-cell complexes were used as calibrators. Capcellia counts from HIV-1-infected patients were compared with those obtained by flow cytometry as the comparison method. The results by Capcellia correlated well with those by flow cytometric analysis: r(2) = 0.95; P <0.001; (y = 0.96x - 22.1); S-y/x = 64 for CD4; r(2) = 0.81; P <0.001; (y = 1.26x - 76.4); S-y/x = 139 for CD8; n = 76. The correlation between CD4+ T-cell counts determined by two trained experimenters was significant (r(2) = 0.96). Our results indicate that this new ELISA technique far lymphocyte immunophenotyping is an efficient alternative to flow cytometry.