Reference values for peripheral blood B-lymphocyte subpopulations: a basis for multiparametric immunophenotyping of abnormal lymphocytes.

Background and Objectives: Immunophenotyping has become a useful tool for the differential diagnosis of chronic B-cell lymphoproliferative disorders. The aim of this work was to determine reference values of normal B-cell subpopulations.
Material and Methods: Blood samples from 38 healthy volunteers were analyzed by multidimensional flow cytometry, using a panel of directly conjugated antibodies. Results were expressed as percent of positive B cells and as median fluorescence intensity, an indirect assessment of the expression level.
Results: CD20, CD22, CD24, CD40, CD79a, CD79b, FMC7, CD11a, CD18, CD44 were positive in the whole B cell population, whereas CD10, CD86, CD103, CD154 and FasL were almost absent from the B-lymphocyte population. 75% were IgD positive. The kappa/lambda ratio was 1.5. CD5, CD23, CD25, CD38, CD43, CD54, CD62L, CD80 and CD95 were positive in different B-cell subpopulations. The utility of all these markers in the differential diagnosis of chronic B-cell lymphoproliferative disorders is discussed.
Conclusion: In order to interpret a pathological immunophenotype, it is necessary to refer to quantitative and qualitative values of normal B-cell subpopulations.