IMMUNOGENETIC CONTROL OF EXPERIMENTAL COLLAGEN-INDUCED ARTHRITIS IN RATS. II. ECIA SUSCEPTIBILITY AND IMMUNE RESPONSE TO TYPE II COLLAGEN (CALF) ARE LINKED TO RT1

The segregation of genes controlling ECIA susceptibility and the level of immune response to native calf type II collagen were determined in the F2 progeny of matings between WF (RTI^u/u; ECIA-susceptible; high responders) and LEW.B3 (RT1^n/n; ECIA-resistant; low to intermediate responders). RT1^n/n F2 progeny showed resistance to ECIA, low skin test reactivity to type II collagen and intermediate levels of IgG anti-collagen antibodies (-log₂ of 6.2 ± 2.6; mean ± SD, n= 10). RT1^u/u and RT1^u/u F2 progeny were susceptible to ECIA and were high responders to type II collagen by skin testing and IgG antibody titres (-log₂ of 12.1 ± 1.3, mean ± SD, n= 26). Although all rats that developed arthritis were also high responders to type II collagen one group of immature F2 progeny, RT1^u/u and RT1^u/n, showed high anti-collagen immune responses in the absence of detectable arthritis. The data indicate that genes linked to RT1.A control susceptibility to ECIA and at least part of the immune response to native calf type II collagen in WF and LEW.B3 rats.