Background. The role of the cytokine, interleukin (IL)-4, in allograft rejection and protection is not clear. We have previously shown that IL-4 transgenically 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 from C57BL/6 donors. The former received pancreas grafts from 1- to 2- day-old BALB/c donors which did or did not transgenically express IL-4 in the graft. Three weeks after the cell infusion, the spleens were removed and the splenocytes 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 mice receiving grafts compared with mice not receiving grafts. The presence of 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 transgenically expressed IL-4 to protect the allograft was not associated with up-regulation of a graft antigen-specific IL-4 response.
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