Lymphocyte immunophenotyping by flow cytometry in normal adults. Comparison of fresh whole blood lysis technique, Ficoll-Paque separation and cryopreservation.

In the present report we have assessed the extent to which Ficoll-Paque separation and cryopreservation of mononuclear cells alter the measurement of lymphocyte subsets by flow cytometry. Standard Ficoll-Paque separation increased the percentage of CD4+, CD19+ and CD4+CD45RA+ cells, as well as decreasing that of CD8+, and CD4+CD29+ cells, compared to the fresh whole blood lysis technique. Moreover, cryopreservation caused a depletion of CD4+ p80+ cells, but normal whole blood values were restored following a short incubation.