Immunophenotyping of T lymphocytes by three-color flow cytometry in healthy newborns, children, and adults.

Reagents are now available which allow simultaneous assessment of three different fluorescence wave-lengths on most commercially available flow cytometers. Such three-color analyses provide more information than single- or dual-color analyses. The present study was undertaken in order to establish age-related differences in lymphocyte subpopulations by simultaneously measuring three surface antigens in newborns, children, and adults. A whole blood method was used to label cells with antibodies conjugated to FITC, PE, and perCP. We found that the percentage of lymphocytes expressing HLA-DR/CD28/CD8, HLA-DR/ CD38/CD8, CD95/CD45RO/CD8, CD95/CD45RO/CD4, CD95/CD4, and CD95/CD8 showed relative increases with age. The percentage of lymphocytes expressing CD28/CD8, CD38/CD8, and CD38/CD4 showed relative decreases with age, while the subset HLA-DR/CD38/ CD4 did not change. Three-color flow cytometry is a powerful tool to more precisely define lymphocyte subsets than the current two-color methods. We present values using a three-color panel in healthy newborns, children, and adults.