DQA1*0103 mice are susceptible to collagen‐induced arthritis. (a) Per cent incidence of arthritis (DQA1*0103, n = 12; DQ6.1, n = 10; DQ6.4, n = 12; FVB, n = 12). (b) Disease severity, *P < 0·001 DQA1*0103 versus DQ6.1 and FVB. DQA1*0103 mice generate CII‐specific cellular and humoral response. (c) Anti‐CII antibodies, DQA1*0103 versus DQ6.4, P < 0·05; DQA1*0103 versus DQ6.1 and FVB, P < 0·02; DQ6.4 versus DQ6.1, P < 0·05; DQ6.4 versus FVB, P < 0·02. (d) In vitro response to recall challenge with CII, DQA1*0103 versus DQ6.1 and FVB, P < 0·04. (e) Cytokines measured from the supernatants of culture in (c). (f) Relative expression of mRNA transcripts of macrophage inhibitory factor (MIF) in splenic cells of transgenic mice. (g) In vitro peptide specific recall response using lymph node cells from mice primed with individual CII‐peptide, and n = 3 to n = 5 mice per strain for all in vitro experiments.