Interleukin-21 and Interleukin-23 levels in familial Mediterranean Fever before and after treatment: the role of cytokines in disease pathogenesis

In a previous study, it has been shown that the population of Th17 lymphocytes was increased in patients with FMF. IL-21 and IL-23 play significant roles in the production and differentiation of Th17 cells. In this study, we aimed to evaluate serum levels of IL-21 and IL-23 in FMF patients both at diagnosis and after treatment, and to compare these levels with those of healthy controls. Twenty-seven newly diagnosed patients with FMF in attack-free periods and twenty-seven healthy volunteers enrolled in the study. The groups were comparable with respect to age and gender. IL-21 and IL-23 levels in serum samples from patients at the time of diagnosis, in remission after treatment, and from the control groups were analysed using the ELISA method. There was no significant difference between the cytokine levels of the patient group at the time of diagnosis and the cytokine levels of the control group (for IL-21, p: 0.28 and for IL-23, p: 0.56). Similarly, there was no significant difference between the patients' cytokine levels at the time of diagnosis and after treatment (for IL-21, p: 0.99 and for IL-23, p: 0.08). Interleukin levels at the time of diagnosis did not differ among patient groups based on the presence of clinical findings or the M694V genotype. Our results suggest that IL-21 and IL-23 do not play a role in the pathogenesis of the disease. However, while interpreting these findings, it should be considered that patients with active episodes were excluded and cytokine levels were not measured in tissue samples.