Although our finding showed that the presence of both IgM and IgG antibodies were significantly higher in RA patients compared with controls, in some articles a lower frequency of IgG antibodies have been reported in RA patients compared with controls, this might be due to persistent or repeated antigenic stimulation induced by cysts, because under some conditions such as starvation, desiccation or extreme temperature, the trophozoite become encysted in a cellulose wall and survive for months or even as long as 24 years (15), a phenomenon such as toxoplasmosis (16, 17). The gene discussed is CD40LG; the disease is toxoplasmosis.