CD79A and rheumatoid arthritis: Given the significantly elevated levels of IgA AHAs against IgG1 F(ab’)2MMP-3 and IgG/IgA AHA against IgG4 F(ab’)2MMP-3 in RA, it seems likely that upregulated immune responses by IgG1/IgG4 F(ab’)2MMP-3 fragments are characteristic of RA.