Requirement for CD8 β Chain in Positive Selection of CD8-Lineage T Cells

Abstract
CD8 is either an αα homodimer or an αβ heterodimer, although most peripheral CD8-lineage T cells express only the CD8αβ heterodimer. The physiological function of CD8β was elucidated with mice that were chimeric for the homozygous disruption of the CD8β gene. The CD8β -/- T cells developed normally to CD4 + CD8 + stage, but did not efficiently differentiate further, which resulted in few peripheral CD8 + T cells. The number of peripheral CD8 + T cells was restored by transfer of an exogenous CD8β gene into CD8β-deficient T cells. Thus, CD8β is necessary for the maturation of CD8 + T cells.