Expression and modulation of the Lewis x antigen (CD15) on the T cell line Molt-4

The T cell lines Molt-4 and H9 exhibited a characteristic distribution of the cell adhesion molecule Lewis x (CD15, lacto-N-fucopentanose III) showing an unusually broad peak by flow cytometry ranging from cells without CD15 to cells with high expression. The cytokines IL-1, IL-2, IFN-beta, IFN-gamma, and TNF-alpha, known to activate T cells, did not affect CD15 expression. However, phorbol myristate acetate and the thymic peptide extract Thymex-L were able to enhance both the number of CD15-positive cells and the median fluorescence. The effects of both inducers were dose- and time-dependent. An additive or synergistic effect was not seen. These data suggest that phorbol esters and distinct thymic peptides can modulate the expression of the cell surface antigen CD15.