In this study, we aimed to comprehensively evaluate the proportions of CD4+ T cell and B cell subpopulations in peripheral blood collected from HCs and RA patients, and compared them between two locations; Tsukuba City and Karuizawa Town, which differ in altitude by 1000 m and, thus, have distinct differences in average air temperature and atmospheric pressure. This evidence concerns the gene CD4 and rheumatoid arthritis.