Protective role of major histocompatibility complex class II Eb^d transgene on collagen-induced arthritis

Collagen-induced arthritis (CIA) is an animal model of autoimmune inflammatory polyarthritis that has features similar to rheumatoid arthritis (RA). Much like RA, susceptibility to mouse CIA is influenced by the major histocompatibility complex (MHC), H-2, and restricted to the H-2^q and H-2^r haplotypes. Whereas the role of the H-2A molecule in susceptibility to CIA is well established, little is known about the role of H-2E molecule in the disease. In this study, we analyzed the effect of a transgenic Eβ^d molecule on CIA susceptibility in a recombinant mouse B10.RQB3, which expresses the CIA susceptible A^q genes and an Ea^k gene, but does not produce an E molecule since Eb^q is nonfunctional. In the presence of an Eb^d transgene, a viable E molecule is generated. Whereas B10.RQB3 were susceptible to CIA, B10.RQB3-Eβ^d+ showed a dramatic reduction in the incidence of arthritis as well as a decrease in the level of anti-mouse and anti-bovine CII antibodies in their serum. No clear cut differences in the expression of T cell receptor (TCR) Vβ was observed between Eβ^d+ and Eβ^d- transgenic mice. Mechanisms underlying the protective effect of Eβ^d transgenic molecule on CIA may shed light on how HLA-DR molecules influence human RA.