HELPER T-LYMPHOCYTE COUNT - TRAX CD4 TEST KIT VERSUS CONVENTIONAL FLOW-CYTOMETRY

Background.-We evaluated a newly developed enzyme-linked immunosorbent assay system for measuring helper T-lymphocyte count. Methods.-Data f rom 111 human immunodeficiency virus-infected injection drug users in a cohort study were analyzed by flow cytometry and independent duplica te runs of the TRAx enzyme-linked immunosorbent assay. Results.-The me an helper T-cell counts were 470, 480, and 506 per microliter by flow cytometry and TRAx runs 1 and 2, respectively. The correlation coeffic ients for TRAx runs 1 and 2 with the flow cytometry results as the dep endent variable were .93 and .91, respectively. A cross-tabulation of the enzyme-linked immunosorbent assay helper T-lymphocyte counts with flow cytometry counts showed agreement of 71% and 76% when the flow co unt was between 201 and 500, and 88% and 90% when it was greater than 500 cells per microliter. In those samples with 200 or fewer helper T cells, agreement was 73% and 41% for each TRAx run. Conclusions.-The T RAx enzyme-linked immunosorbent assay system is an acceptable method f or measuring helper T-lymphocyte count, but should be recalibrated for better performance at helper T-cell counts below 200 per microliter.