The cross-reactivity of I-Ag7 and I-Ad tetramers

To investigate the cross reactivity between glutamic acid decarboxylase (GAD) I A g7 and I A d tetramer in diabetes prone non obese diabetic (NOD) mice (I A g7 ) and diabetes free Balb/c mice (I A d) Methods Two GAD peptide I A g7 and I A d tetramers were generated and compared for phenotype and function of sorted GAD peptide I A g7 and I A d tetramer positive (tet +) T cells Results The cross reactivity is shown in either tetramer positive percentage or tetramer staining intensity The NOD and Balb/c derived tet + T cells were able to be cross stained by GAD peptide I A g7 and I A d tetramers, and responded to both irradiated NOD and Balb/c splenotyes under stimulation by synthetic and recombinant GAD peptides Conclusion Although I A g7 and I A d are closely related in biochemical and biological aspects, their most notable difference is the presence or absence of a negatively charged residue at position β57 that links to insulin dependent diabetes mellitus