Figure 2. Generation of NOD mice that have a class II deficiency on the B cells (NOD.B^CIID mice).

NOD mice were crossed with I-A^b-/- B6 mice on the H-2^b genetic background (K^bD^b) to generate NOD mice expressing the class II knockout mutation. Since MHC class I is in strong linkage disequilibrium with MHC class II, the introduction of the MHC class II knockout mutation introduces not only I-A^b-/- but also alters the MHC class I molecules of the NOD haplotype (K^dD^b) to K^bD^b. NOD female mice then were irradiated and reconstituted with bone marrow from these NOD.I-A^b-/- mice and NOD.µMT-/- mice. This generated mice that had T cells and non-B cell antigen-presenting cells from both NOD I-A^b-/- mice and NOD.µMT-/- mice. Therefore, the resulting mice expressed the NOD I-A^g7 (derived from the NOD.µMT-/- mice) on the non-B cell antigen-presenting cells. However, in the B cell compartment, the mice would only express B cells from the NOD I-A^b-/- mice as NOD.µMT-/- mice do not have mature B cells. Thus the B cells would not express MHC class II and the MHC class I molecules are de-rived from the H-2^b haplotype. All the other cells in the NOD B^CIID mice express MHC molecules of both H-2^g7 (K^dD^bI-A^g7) and I-A^b-/- (K^bD^b) haplotypes.