IL6 and rheumatoid arthritis: In a similar line of study, the basal levels of serum proinflammatory cytokines, Interleukin 6 (IL-6) and Tumor Necrosis Factor alpha (TNF-alpha), were markedly higher in the rheumatoid arthritis patients than the healthy controls; the serum levels of IL-6 and TNF-alpha significantly reduced in the rheumatoid arthritis patients after laughter intervention (Matsuzaki et al., 2006).