HLA-C and rheumatoid arthritis: To search for disease-causative pathogens, numerous studies on antibody responses to putative pathogens were conducted, and commonly concluded that antibodies against putative pathogens are higher, or cross-react with major histocompatibility complex (MHC) molecules or other autologous components such as collagen in rheumatoid arthritis (RA) [1], and cardiac myosin in rheumatic heart disease [2].