IL1A and rheumatoid arthritis: However, there is a possibility of lower efficacy of treatment, for instance with b/tsDMARDs, in HTLV-1-positive compared to -negative RA patients because HTLV-1 infection of T-cells and synovial fibroblasts has been shown to induce enhanced production of cytokines such as TNF-α, IL-1α (30–32).