Moreover, it has been reported that cytotoxic T-lymphocyte antigen 4 immunoglobulin fusion protein (CTLA-4Ig) and antibodies to tumor necrosis factor- α (TNF-α) and IL-6, which are very effective in the treatment of RA patients [18-20], also show therapeutic effects in GPI-induced arthritis [21]. This evidence concerns the gene TNF and rheumatoid arthritis.