Interleukin-4 secretion by the allograft fails to affect the allograft-specific interleukin-4 response in vitro

Background. The role of the cytokine, interleukin (IL)-4, in allograft reje ction and protection is not clear. We have previously shown that IL-4 trans genically expressed in a pancreas allograft does not protect the allograft from rejection. Here, we analyze the effect of the transgenically expressed IL-4 on the cytokine profile of the allograft-specific immune response. Methods. C57BL/6SCID mice were infused with small numbers of spleen cells f rom C57BL/6 donors. The former received pancreas grafts from 1- to 2-day-ol d BALB/c donors which did or did not transgenically express IL-4 in the gra ft. Three weeks after the cell infusion, the spleens were removed and the s plenocytes were restimulated in vitro with BALB/c APC, and third party BALB .K APC. IL-2 and IL-4 levels in the culture supernatants were measured. Results. The presence of a pancreatic allograft induced an increase in the levels of both IL-2 and IL-4 in culture supernatants from splenocytes of mi ce receiving grafts compared with mice not receiving grafts. The presence o f IL-4 transgenically expressed in the pancreas allograft had no effect on the in vitro cytokine profile. Conclusions. from these results we conclude that the failure of transgenica lly expressed IL-4 to protect the allograft was not associated with up-regu lation of a graft antigen-specific IL-4 response.