Expression of Sialyl Lewisx Antigen on Human T Cells

Sialyl Lewisx (sLex) antigen, which has been introduced as tumor-associated cell surface carbohydrates, was demonstrated to be expressed on a subpopulation of human CD4+ and CD8+ T cells. It was also demonstrated that the majority of γδT cells as well as natural killer cells expressed a high level of sLex antigen. The sLex expression on T cells were up-regulated by activation with various T cell stimulants. The sLex+ CD4+ T cells were enriched in CD4+ CD45RO+ memory type of T cells but not in CD4+CD45RA+ T cells. Moreover, sLex+ CD4+ T cells were demonstrated to show higher proliferative responses to T cell stimulants such as CD4+CD45RO+ T cells. These results initially clarified the expression of sLex carbohydrate on human T cells and indicated the important role of sLex-expressing T cells in immune responses.