A MANUAL BEAD ASSAY FOR THE DETERMINATION OF ABSOLUTE CD4(-INFECTED INDIVIDUALS() AND CD8(+) LYMPHOCYTE COUNTS IN HUMAN IMMUNODEFICIENCY VIRUS)

CD4(+) T lymphocytes are currently the most common surrogate marker in dicating disease progression in individuals infected with human immuno deficiency virus (HIV), Since the cost of enumerating lymphocyte pheno types is quite high, an inexpensive bead assay analyzed by light micro scopy (cytosphere assay; Coulter Corporation, Hialeah, Fla.) was devel oped as an alternative method for counting CD4(+) and CD8(+) T lymphoc ytes, To evaluate the reliability of the cytosphere assay, heparinized blood was collected from 117 HIV-infected individuals and tested for both CD4(+) and CD8(+) lymphocytes by flow cytometry and the cytospher e? assay. The Pearson correlation coefficient of the cytosphere assay compared with that of flow cytometry for CD4(+) T lymphocytes was 0.93 , with mean values a standard deviations of 534 +/- 509 by flow cytome try and 499 +/- 477 by the cytosphere assay, The correlation coefficie nt for CD8(+) T lymphocytes was 0.86, with mean values of 831 +/- 543 by flow cytometry and 746 +/- 472 by the cytosphere assay, The sensiti vity and specificity of the cytosphere assay in determining absolute C D4(+) T-lymphocyte counts of less than 200/mu l were 97.6 End 94.7%, r espectively, The positive; predictive value was 90.9%; and the negativ e predictive value was 98.6%, The cytosphere assay was highly correlat ive to how cytometry in determining CD4(+) and CD8(+) T-lymphocyte cou nts among HN-infected patients, The ease and limited resources needed to perform this test make it ideal in developing countries and other a reas where technology and finances are limited.