DETERMINATION OF CD4 AND CD8 LYMPHOCYTE SUBSETS BY A NEW ALTERNATIVE FLUORESCENCE IMMUNOASSAY

The purpose of this study was to evaluate a new alternative fluorescen ce immunoassay method (Zymmune CD4/CD8 Cell Monitoring Kit; Zynaxis, I nc., Malvern, Pa.) for determining the absolute CD4(+) and CD8(+) T-ly mphocyte concentrations in, whole blood. The investigation was perform ed as a two-site comparison of the reference whole blood flow cytometr ic method with the Zymmune method. In this investigation, a total of 1 66 patient samples were evaluated of which similar to 20% were from hu man immunodeficiency virus-positive individuals. The mean value for sa mples performed by the Zymmune CD4 assay was 1,094 (range, 74 to 2,586 ) cells per mu l, while the reference method yielded a mean of 890 (ra nge, 35 to 2,033) cells per mu l. The correlation coefficient for regr ession analysis was 0.940. The mean value for samples performed by the Zymmune CD8 assay was 700 (range, 212 to 1,813) cells per mu l, while the reference method yielded a mean of 545 (range, 82 to 2,158) cells per yl. The correlation coefficient for regression analysis was 0.921 . No site-specific differences or trends in CD4 or CD8 values were see n when the data were analyzed by site of collection. The average preci sion of the CD4 assay varied from 6 to 14%, corresponding to the high and low concentration ranges. For CD8, the average precision varied fr om 8.3 to 16% over the respective high to low concentration ranges, We conclude that the Zymmune CD4/CD8 Cell Monitoring Kit method provides absolute CD4(+) and CD8(+) T-lymphocyte concentrations which are equi valent to those given by the reference flow cytometric method.