IL4 and osteochondritis dissecans: Furthermore, increased levels of inflammatory cytokines in the olfactory cleft have been correlated with OD; elevated levels of IL-4, IL-5, and IL-13 are indeed associated with worse scores in olfactory identification tests; smell disorders have a direct correspondence with the elevated levels of cytokines IL-4 and IL-13, although the key role of the IL-4 and IL-13 pathways and their possible regulatory implications on the neurogenesis and homeostasis of olfactory neurons has not yet been fully clarified and explained [16].