The kinetics and temporal expression of T-cell activation-associated antigens CD15 (LeuM1), CD30 (Ki-1), EMA, and CD11c (LeuM5) by benign activated T cells.

Cell surface antigens, including CD71 (T9), CD38 (T10), HLA-DR, CD25 (IL2-R), CD15 (LeuM1), CD30 (Ki-1), epithelial membrane antigen (EMA), and CD11c (LeuM5), have been identified on the surface of neoplastic T-cells. The significance of this expression is unknown since the expression of these antigens by benign T cells has not been fully investigated. In this study the kinetics, temporal relation and hierarchy of expression of these eight cell surface antigens by purified normal peripheral blood T cells following activation with phytohemagglutinin (PHA) were investigated using one- and two-color flow cytometry. All eight antigens were expressed in a hierarchical manner following activation of normal peripheral blood T cells with PHA. The sequence of antigen expression and the initial time point of this expression was: CD38, < 24 h; CD71, CD25, 24 h; EMA, HLA-DR, CD15, 48-72 h; CD30, 72 h; and CD11c, 96-120 h. The maximum percentage of T cells expressing each antigen and the time point of maximum expression was: CD38 96% at 14 and 17 days; CD71 88%, CD25 94%, EMA 55%, and CD30 31% at 96 h; CD15 56% at 120 h; HLA-DR 30% at 168 h; and CD11c 42% at 240 h. The expression of these 8 antigens clustered into six distinct immunophenotypic constellations: Group I: None; Group II: CD38 with CD71 and/or CD25; Group III: CD38, CD71, CD25 with HLA-DR, CD15 and/or EMA; Group IV: CD38, CD71, CD25, EMA, HLA-DR with CD15, CD30 and/or CD11c; Group V: CD38, CD25, CD11c with CD71, EMA and/or HLA-DR; Group VI: CD38 with CD25 and/or CD11c. Finally, EMA and CD11c were preferentially expressed by CD4 and CD8 T cells, respectively. In summary, these results demonstrate that all eight antigens (1) are associated with T-cell activation, (2) are expressed in a hierarchical manner following activation, and (3) that this expression clusters into distinct immunophenotypic constellations.