In a study reported by Kokkonen et al., increases in the concentrations of IL-1β, IL-2, IL-6 and those indicative of activation of Th1 cells, specifically IFN-γ and IL-12, together with those of a co-existent anti-inflammatory response (IL-10 and IL-1 receptor antagonist) were found to pre-date the onset of clinically evident RA (93). Here, IFNG is linked to rheumatoid arthritis.