INCREASE IN POSITIVE SELECTION OF CD8(-CELLS IN TAP1-MUTANT MICE BY HUMAN BETA(2)-MICROGLOBULIN TRANSGENE() T)

Mice harboring a deletion of the gene encoding the transporter associa ted with antigen presentation-1 (TAP1) are impaired in providing major histocompatibility complex (MHC) class I molecules with peptides of c ytosolic origin and lack stable MHC class I cell surface expression. T hey consequently have a strongly reduced number of CD8(+) T cells. To examine whether selection of CD8(+) T cells is dependent on TAP-depend ent peptides, we partially restored MHC class I cell surface expressio n in TAP1-deficient mice by introduction of human beta 2-microglobulin . We show that selection of functional CD8(+) T cells can be augmented in vivo in the absence of TAP1-dependent peptides.