Substitution of Glutamic Acid at Position 71 of DRβ1*04:01 and Collagen-Specific Tolerance Without Alloreactivity.

OBJECTIVE

The DRB1 locus is strongly associated with both susceptibility and resistance to rheumatoid arthritis (RA). DRB1 alleles encoding the VKA or VRA epitope in positions 11, 71, and 74 confer the highest risk of developing RA, whereas the allele encoding VEA is protective. We therefore investigated the feasibility of creating antigen-specific tolerance without inducing alloreactivity by replacing lysine with glutamic acid at position 71 in DRβ1*04:01.

METHODS

Individual DRB1 alleles and the DRB104:01 allele were cloned into T2 cell lines to measure binding of biotinylated peptides. Transgenic animals expressing DRB104:01, DRB101:01, or DRB104:01 were injected with collagen to measure T cell proliferation. Skin and bone marrow transplants between DRB104:01 and DRB104:01 mice were performed to determine if the single amino acid change at position 71 would be recognized as foreign. DRB104:01 mice transplanted with DRB104:01 bone marrow were injected with collagen to test if resistance to collagen sensitization could be transferred.

RESULTS

Replacing lysine (K) at position 71 in DRβ104:01 with glutamic acid (E) blocked collagen peptide binding and rendered the DRB104:01 mice resistant to collagen sensitization. Skin and bone marrow transplants from DRB104:01 mice were not rejected by DRB104:01 mice, suggesting the single E difference was not recognized as allogeneic. Bone marrow from DRB104:01 mice adoptively transferred antigen-specific tolerance to collagen to DRB104:01 mice.

CONCLUSION

These studies demonstrate that editing a single amino acid in DRβ1*04:01 blocks collagen peptide binding without inducing alloreactivity and could therefore represent a gene therapy approach to induce antigen-specific passive tolerance.