IL6 and Arthritis: The reason is that CRP is a protein produced by liver cells, and its concentration increases during inflammatory processes, where it is stimulated by pro-inflammatory cytokines, especially interleukin-6, which is the cytokine that causes arthritis.26 The patients also displayed a high ESR level, where its elevation indicates the presence of inflammation in the body, as inflammatory conditions lead to an increase in the number of proteins in the blood plasma.