Difference in cytokine production in acute and chronic rejection of rat lung allografts

In Brown Norway to Lewis rat lung transplantation, short-term administration of cyclosporine produces permanent adoption of allografts; however, the adopted grafts show symptoms of chronic rejection. To clarify the difference in cytokine production in acute an chronic rejection of the allografts, an immu-nohistochemical study was performed. In acute rejection, positive cells for respective cytokines were observed in infiltrating cells, increasing in number as the days after transplantation passed, and reaching a maximum on the fifth day. The strongest reactivity was observed perivenously. In chronic rejection, TNF-α positive cells were observed in the perivascular and peribron-chial regions, especially around class II positive epithelia. The number of positive cells was, however, less than that in the vascular phase of acute rejection. Few cells were positive for IL-lβ, IFN-γ and, unexpectedly, for IL-4. These facts indicate the functional difference of infiltrating cells between acute and chronic rejection.