CD4, CD8 AND TYROSINE KINASES IN THYMIC SELECTION

Analysis of T-cell development in transgenic and gene-deficient mice s uggests that the co-receptor,function of CD8 is essential for positive selection. Recent data also demonstrate that the requirement for CD4 and CD8 in negative selection of T cells is not absolute and may be re gulated by T-cell receptor affinity for the deleting ligand, an interp retation consistent with the affinity model of thymic selection. In ad dition to its association with CD4 and CD8, it appears that p56lck is also important during the early stages of thymic development.