Comparison of basic lymphocyte phenotype results between a diagnostic and a research laboratory.

Objective: Lymphocyte phenotyping is a valuable tool for monitoring the effects of antiretroviral therapy on individuals living with HIV-1. A switch study was conducted to compare T-cell subset quantification performed by a research laboratory and a diagnostic, laboratory to understand the impact on the retrospective and prospective results of a long-term study.

Methods: Using FACSCanto II Flow Cytometers, EDTA anticoagulated peripheral blood from 73 males enrolled in the Multicenter AIDS Cohort Study/Women Interagency HIV Combined Cohort Study was analyzed by both a research (laboratory 1) and a diagnostics laboratory (laboratory 2) for quantification of cluster of differentiation (CD)3, CD4, and CD8 T-cells. There were 47 males living with and 26 living without HIV-1.

Results: Bland-Altman (B-A) analysis was applied to assess the agreement between laboratory 1 and laboratory 2 results. There were 69 out of 73 CD3, 71 out of 73CD4, and 72 out of 73 CD8 T-cell results that fell within acceptable B-A limits of agreement. The mean differences between the 2 laboratories were -1.000, -0.945, and +0.685(%), respectively.

Conclusion: The strong agreement between results from laboratory 1 and laboratory 2 for CD3, CD4, and CD8 T-cell percentage suggests that the difference between laboratories using the same instrumentation and methodology will have a minimal effect on long-term study results.