“…19,21,22 IL-4 is a Th2 cell-derived cytokine that inhibits IL-2 and IFNg production by Th1 cells, promotes Th2 cell differentiation, and inhibits proinflammatory cytokine (IL-4, IL-6, IL-8 and TNFa) production by monocytes/ macrophages. 23 Several studies that have investigated the role of IL-4 in allograft rejection, either by systemic administration of rIL-4, [24][25][26] use of IL-4 knockout or transgenic mice, 27 or IL-4 gene transfer to the graft, 28 suggest that IL-4 functions to prolong transplant survival. On the other hand, administration of soluble IL-4R delays heart allograft rejection, 29 whereas IL-4-deficient mice can reject allografts with the same vigor as wildtype recipients, and develop the same extent of obliterative vasculopathy as those transplanted to wild-type counterparts.…”