Expression of an avian CD6 candidate is restricted to αβ T cells, splenic CD8+γδ T cells and embryonic natural killer cells

摘要

AbstractA candidate avian CD6 homolog is identified by the S3 monoclonal antibody. The S3 antigen exists in a phosphorylated glycoprotein form of 130 kDa and a nonphosphorylated form of 110 kDa. Removal of phosphate groups and N‐linked carbohydrates indicates a 78‐kDa protein core. During thymocyte differentiation, the γδ T cells do not express S3, whereas mature CD4+and CD8+cells of αβ lineage acquire S3 antigen. All αβ T cells in the blood and spleen express the S3 antigen at relatively high levels. In contrast, only the CD8+sub‐population of γδ T cells in the spleen expresses the antigen and neither αβ nor γδ T cells in the intestinal epithelium express the S3 antigen. The S3 antigen is also found on embryonic splenocytes with a phenotypic profile characteristic of avian natural killer cells. The biochemical characteristics and this cellular expression pattern imply that the S3 antigen is the ch