In autoimmune diseases including rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE), cytokines
play a central role in initiating and maintaining diverse immune and inflammatory responses. Interleukin 22 (IL-22), a
member of IL-10 cytokine family, has been believed to be an important player in regulating inflammatory responses
associated with many autoimmune diseases. The aim of this study was to detect the role of IL-22 and Tumor necrosis
factor receptor associated factor 1 (TRAF1) in patients with RA and SLE and their correlation with disease activity. The
current study was conducted on 70 RA, 64 SLE patients and 45control subjects from Egyptian population, using ELISA to
assess IL-22 in culture supernatants of cultured lymphocytes and TaqMan genotyping assay for TRAF1 (rs10818488). A
significant increase in IL-22 levels in both RA and SLE patients than control group (pbefore and after lymphocyte stimulation. Also, a significant differences in A allele frequency with RA patients was found
(P=0.030) indicating that TRAF1 could be considered as a susceptibility gene to RA in the Egyptian population. The A
allele of TRAF1 was significantly increased RA patients with positive rheumatoid factor (RF) (p=<0.001) and/or anti-
CCP antibodies (p=0.034), this could not be demonstrated in SLE patients or controls(P=0.750). Also, IL-22 level
correlated positively with disease activity in RA and SLE patients which may rise a possible role in the pathogenesis of
both conditions. [Egypt J Rheumatology & Clinical Immunology, 2016; 4(1): 49-58]