PROBLEM : Due to the lack of classical HLA antigens on the trophoblast , fetal antigens are possibly presented in a non major histocompatibility complex ( MHC ) restricted way .
problem : due to the lack of classical hla antigens on the trophoblast , fetal antigens are possibly presented in a non major histocompatibility complex ( mhc ) restricted way .
O O O O O O O B-protein_family_or_group I-protein_family_or_group I-protein_family_or_group O O O O B-protein_family_or_group I-protein_family_or_group O O O O O B-other_name B-protein_family_or_group I-protein_family_or_group I-protein_family_or_group O B-protein_complex O O O O