Evaluation of a dual‐color flow cytometry immunophenotyping panel in a multicenter quality assurance program

A basic immunophenotyping panel that employed dual‐color combinations of fluorescein isothiocyanate (FITC) and phycoerythrin (PE) conjugated monoclonal antibodies (mAb; FITC‐CD45/PE‐CD14, FITC‐IgG₁/PE‐IgG₂, FITC‐CD3/PE‐CD8, FITC‐CD3/PE‐CD4, FITC‐CD3/PE‐CD16+PE‐CD56, and PE‐CD19) was utilized in a quality assurance program to determine whether the 4 laboratories participating in a multicenter AIDS study obtained similar lymphocyte subset percentage values for T cells, B cells, NK cells, and CD4⁺ and CD8⁺ T cells. Over a 1½ year period, 78 shared peripheral blood specimens Were prepared and analyzed in each laboratory. The CD45^brightCD14⁻ percentage for each specimen was used to correct that individual's lymphocyte subset values. Interlaboratory coefficients of variation (CV) for the human immunodeficiency virus type I (HIV) seronegative (n = 38) and HIV‐seropositive (n = 40) specimens using this panel were <3% for total T cells; <5% for CD4⁺ T cells and CD8⁺ T cells; ≤17% for B and NK cells; and <8% for CD4^T/CD8^T ratios. The 6‐tube basic immunophenotyping panel has several notable features: (a) for clinical studies, it permits comprehensive evaluation of an individual's major lymphocyte subsets, i.e., T, B, NK, and CD4⁺ and CD8⁺ T cells; (b) for interlaboratory proficiency testing programs, it allows the detection of differences among laboratories in measurements of several functionally distinct cell populations; and (c) for within‐sample quality assurance, it provides several quality control checks, including the lym‐phosum, i.e., the sum of an individual's corrected T + B + NK values, a sum that was generally 100 ± 5% on the HIV‐seronegative specimens analyzed in this study. © 1993 Wiley‐Liss, INc.