REQUIREMENT FOR CD8 BETA-CHAIN IN POSITIVE SELECTION OF CD8-LINEAGE T-CELLS

CD8 is either an alphaalpha homodimer or an alphabeta heterodimer, alt hough most peripheral CD8-lineage T cells express only the CD8alphabet a heterodimer. The physiological function of CD8beta was elucidated wi th mice that were chimeric for the homozygous disruption of the CD8bet a gene. The CD8beta-/- T cells developed normally to CD4-CD8+ stage, b ut did not efficiently differentiate further, which resulted in few pe ripheral CD8+ T cells. The number of peripheral CD8+ T cells was resto red by transfer of an exogenous CD8beta gene into CD8beta-deficient T cells. Thus, CD8beta is necessary for the maturation of CD8+ T cells.