IL17A and rheumatoid arthritis: Interleukin-17 cytokines play an important role in diseases such as multiple sclerosis, asthma, rheumatoid arthritis, psoriasis and atopic dermatitis, and arthritis; hence, for example, recombinant human monoclonal antibodies that bind IL-17A (secukinumab, ixekizumab, and brodalumab) have been used in the treatment of moderate-to-severe psoriasis.