Capillary blood as an alternative specimen for enumeration of percentages of lymphocyte subsets

OBJECTIVE: Capillary blood has been increasingly used in point-of-care setting for clinical monitoring in immunology and infectious diseases. We explored whether percentages of lymphocyte subsets (T-cells; CD3+, helper T-cells; CD4+, cytotoxic T-cells; CD8+, B-cells; CD19+, NK cells; CD56+, gamma delta T-cells, and regulatory T-cells) with regard to total lymphocyte count from capillary and venous blood of healthy volunteers were in good agreement. RESULTS: All percentages of lymphocyte subsets with regard to total lymphocyte count from capillary blood were significantly correlated with those from venous blood (r ≥ 0.9 for every cell type). However, Bland–Altman plots showed high agreement between capillary and venous samples only in those of CD3+, CD4+, and CD8+ cells (limit of agreement percentages from mean venous blood < 20%). However, the agreement of percentages of other lymphocyte subsets from venous and capillary blood was mediocre. We concluded that capillary blood could be used as an alternative for venous blood to determine percentages of CD3+, CD4+, and CD8+ cells with regard to total lymphocyte count.