Expression of a class I MHC transgene: effects of in vivo alpha/beta-interferon treatment.

Transgenic mice containing a swine class I major histocompatibility complex (MHC) gene, PD1, express swine MHC (SLA) antigen. The tissue distribution of PD1 RNA parallels that observed in the swine, indicating that the expression of PD1 is regulated and that trans-acting factors involved in this regulation have been conserved between the species. Although PD1 RNA levels were much greater in transgenic spleen than in thymus, no difference in the chromatin organization of the PD1 gene was detected. In both tissues, a single DNase I hypersensitive site mapped within the 5' flanking region. In vivo treatment of the transgenics with mouse alpha, beta-interferon increases PD1 expression in a number of tissues. In the spleen, this increase parallels that observed for the endogenous transplantation antigen, Kb, but differs markedly from the differentiation antigen, Qa-2. Increases in cell surface expression of both PD1 and Kb occurred equally in splenic T- and B-cell populations following alpha, beta-interferon treatment. In contrast, Qa-2 expression in B cells was enhanced by alpha, beta-interferon, whereas it was unaffected in T cells and thymocytes.