SELECTION OF A BROAD REPERTOIRE OF CB4(-CELLS IN H-2MA(0() T)0) MICE/

According to past reports, H-2Ma(0/0) mice express a single major hist ocompatiblity complex class II molecule, A(b), heavily loaded with a s ingle peptide derived from the invariant chain, CLIP. Despite the high ly restricted diversity of the class Il:peptide complexes expressed on thymic stromal cells in the mutant animals, a large and diverse popul ation of CD4(+) T cells is positively selected. However, two important issues remained unresolved and al are addressed here: Just how prepon derant is CLIP occupancy of the class II molecules from H-2M(0/0) mice ? How extensive and functionally competent is the CD4+ population sele cted in the mutant animals? Our results argue that a single class il:p eptide complex can select a very broad, though not complete, repertoir e of CD4+ T cells.