DIFFERENTIAL EXPRESSION OF T-CELL ANTIGENS IN NORMAL PERIPHERAL-BLOODLYMPHOCYTES - A QUANTITATIVE-ANALYSIS BY FLOW-CYTOMETRY

Aims-To obtain reference values of the level of expression of T cell a ntigens on normal lymphocyte subsets in order to disclose differences which could reflect their function or maturation stages, or both. Meth ods-Peripheral blood from 15 healthy donors was processed by flow cyto metry with triple colour analysis. For each sample phycoerythrin (PE) conjugated CD2, CD4, CD5, CD8, and CD56 monoclonal antibodies were com bined with Cy5-R-phycoerythrin (TC) conjugated CD3 and fluorescein iso thiocyanate conjugated CD7; CD2- and were also combined with CD3-TC an d CD4-FITC. Standard microbeads with different capacities to bind mous e immunoglobulins were used to convert the mean fluorescence intensity (MFI) values of the lymphocyte subsets identified by multiparametric flow cytometry into the number of antigen molecules per cell, measured as antibody binding capacity (ABC). Results-CD4+ (helper/inducer) T c ells exhibit a higher CD3 antigen expression compared with CD8+ (suppr essor/cytotoxic) T lymphocytes. Within the CD4+ T cells, the CD4+CD7- subset expressed a lower level of CD3 compared with CD4+CD7+ and CD8+C D7+ cells, and higher CD2 and CD5 expression than the main CD3+CD7+ su bset. Major differences in antigen expression were also detected betwe en CD3+ T cells and CD3-CD56+ natural killer (NK) cells: NK cells exhi bited higher levels of CD7 and CD56 and lower levels of CD2 and CD5 th an T cells. Significantly lower CD5 expression was also detected in th e small CD5+ B lymphocyte subset compared with T cells. Conclusions-Qu antitative flow cytometry with triple colour analysis may be used to d etect antigen modulations in disease states and to increase the accura cy of diagnosis by comparison with findings in normal counterparts.