Human leukocyte antigen-DRB1*1502 (DR2Dw 12) transgene reduces incidence and severity of arthritis in mice

A strong correlation exists between susceptibility to RA in humans and some DRB1 * alleles of the MHC region such as DRB1* 0.401 and DRB1 *0101. Meanwhile, incidences of other specificities, such as DR2* DR5, or DR7 have been found reduced among RA patients. Like RA, susceptibility to mouse CIA is influenced by the MHC class II loci. To analyze the effect of a DRB1 molecule associated with low incidence of RA on mouse CIA, a human DRB1*1502 (DR2Dw12) transgene was introduced inter CIA-susceptible B10.RQB3 (H2A⁺¹) mice. Transgene-positive DHRB1*1502 mice showed a significant reduction in the incidence and severity of arthritis. Moreover, the clinical reduction of arthritis correlated with the T-cell proliferative response of B10.RQB3- DRB1*1502 mice against a self-derived DRBI peptide from the third hypervariable region. Our results suggest that the DRB1 *1502-mediated protection against CIA can be explained by the DRBI molecule acting as a source of self-antigenic peptide which interferes with the T-cull response against immunodominant region(s) of the arthritogenic type II collagen molecule. By analogy, a similar mechanism might play a critical role in influencing the class II-associated predisposition to RA.