POSITIVE SELECTION OF SELFREACTIVE AND ALLOREACTIVE CD8-CELLS IN TAP-1 MUTANT MICE( T)

Mice with a homozygous deletion in their Tap-1 gene (-/- mice) express very low levels of cell membrane major histocompatibility complex cla ss I molecules and have <1% peripheral CD8(+) T cells. We show that th ese -/- mite but not their +/- littermates display strong primary syng eneic anti-H-2K(b) and -D-b-specific responses mediated by CD8(+) T ce lls. These responses are augmented by in vivo priming. Further, -/- mi ce primed in vivo with H-2(d) alloantigens generate an anti-H-2(d) res ponse which appears nearly as strong as that found in +/- littermates. Both -/- anti-H-2(b) and anti-H-2(d) T cells do not recognize target cells from Tap-1 -/- animals or Tap-2-deficient RMA-S cells. Thus, som e CD8(+) anti-self and alloreactive T cells tan be selected in the abs ence of Tap proteins.