Our results are similar to those reported by Horowitz et al. (2000), who detected antibodies against M. fermentans in 50% of patients with RA and 20% of patients with other arthritis; however there are differences respect to M. fermentans peptides detected, while Horowitz et al. detected antibodies to p107, p48 and p29, we reported antibodies to p70 and p48, the differences probably are due to the different strains and the technique used for the antigen extraction [31]. This evidence concerns the gene RBL1 and rheumatoid arthritis.