HLA-C and escherichia coli infection: To investigate the contribution of maternal immunological changes driven by mismatch between maternal and fetal MHC haplotype antigens, E. coli infection susceptibility was evaluated in C57BL/6 (H-2b) female mice bearing allogeneic pregnancies (sired by BALB/c H-2d male mice) and compared with that of mice with syngeneic pregnancies (sired by C57BL/6 H-2b male mice) (Fig. 2A).