In vivo effects of interferon-y and anti-interferon-y antibody on the experimentally induced lichenoid tissue reaction

We investigated the in vivo effect of recotnbinant interferon-y (IFN-7) and tumour necrosis factor y. (TNF-a) treatment of mice on the development of the delayed-type hypersensitivity (DTH) reaction and hchenoid tissue reaction (LTR) following the local injection of cloned autorcactive T cells. Both the DTH reaction and the LTR were significantly enhanced by pretreatment with IFN-y, but not with TNF-a. Induction of class II MHC antigens on keratinocytes was not essential for the enhancement by IFN-7. Administration of anti-IFN-y antibody reduced the DTH reaction and LTR, although complete inhibition was not observed with our treatment regimen. The ability of IFN-y to increase the number of the cloned T cells invading the epidertnis in vivo, is in keeping with our previous observation that IFN-y treatment of cultured keratinocytes markedly increased the adherence reaction between T cells and keratinocytes in vitro.