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 from 111 human immunodeficiency virus-infected injection drug users in a cohort study were analyzed by flow cytometry and independent duplicate runs of the TRAx enzyme-linked immunosorbent assay.

RESULTS

The mean helper T-cell counts were 470, 480, and 506 per microliter by flow cytometry and TRAx runs 1 and 2, respectively. The correlation coefficients for TRAx runs 1 and 2 with the flow cytometry results as the dependent 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 count 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 TRAx enzyme-linked immunosorbent assay system is an acceptable method for measuring helper T-lymphocyte count, but should be recalibrated for better performance at helper T-cell counts below 200 per microliter.