Flow cytometric analysis of some activation/proliferation markers on human thymocytes and their correlation with cell proliferation.

We immunophenotyped cells from ten human thymuses with emphasis on expression of the CD38 and CD71 antigens. These antigens play role in activation cells and increased expression of them was observed in some leukemia. Simultaneously, certain attention has also been devoted to some further activation markers, e.g. CD25, CD26 and HLA-DR. The classification of leukemia is based on comparison of normal and pathological cells. The study of expression of CD38, CD71 and other markers on thymocytes simultaneously with DNA analysis can be useful for answer if expression of CD38 and CD71 on pathologic cells is a sign of their proliferative ability, a part of immature phenotype in some leukemia, or it is a case of aberrant immunophenotype. In our study, 94% thymocytes were CD38+ and only 16% were CD71+. From our immunophenotypic results including MESF (molecules of equivalent soluble fluorochrome) values and analysis of the cell cycle, the conclusion could be drawn that antigen CD71 can participate in regulation of thymocyte development and presence of both -CD38 and CD71 on pathologic cells will be in all probability the case of aberrant phenotype. We observed a clear correlation of the percentage and MESF values of CD71-positive cells with the cell proliferation only after in vitro thymocytes stimulation with PHA and IL-2. In summary, a strong parallelism was observed regarding the positive relationship between the proliferative rate (assessed by the number of S-phase cells) of stimulated thymocytes and the quantitative (% and MESF) values of some markers - CD71, CD25, CD26 and HLA-DR and negative one with CD38 marker values.