CDw108 expression during T‐cell development

Abstract: We recently reported a gene encoding the human CDw108, a glycosylphosphatidylinositol (GPI)‐anchored membrane glycoprotein that is preferentially expressed on activated T lymphocytes and erythrocytes. The present study investigated the expression of CDw108 on various tissues and cells, particularly on T cells during development. The murine CDw108 cDNA was cloned initially, and it was highly homologous to the human CDw108 (88.0% or 89.3% similarity at the nucleotide or amino acid level, respectively) or identical to the murine semaphorin K1/Sema7A. The CDw108 mRNA was demonstrated in a few tissues including thymus and brain with the highest expression coming on day 7 in whole embryo followed by relatively consistent expression during development. Cell‐surface expression of the CDw108 during T‐cell development was further examined by flow cytometry in the human umbilical cord blood and thymus. It was preferentially expressed on a CD34 + stem cell population of umbilical cord blood, and CD3 dull CD34 +/‐ CD117 (c‐kit) + CD4 bright CD8 bright cells in the thymus that are involved in the stage of positive selection. These results suggest the contribution of CDw108 in T‐cell development, especially in the stage of positive selection in the thymus ( Note ).