IMMUNOGENICITY OF RAT RENAL ALLOGRAFT NEPHRON COMPONENTS IN VIVO

Abstract

Cultured rat nephron components--i.e., tubular cells, glomerular mesangial cells, and glomerular epithelial cells--were compared with cultured rat heart endothelial cells for their in vivo immunogenicity using the primed rejection assay (PRA). Gamma-interferon (gIFN) was used to regulate the class I and class II MHC antigen expression of the cells tested. The heart endothelial cells proved to be the only cell type capable of inducing a maximal rejection response in the native state. This was achieved with a cell number of 10(6) when the survival of a subsequent heart allograft from a relevant donor was reduced from 5 to 3 days. All kidney nephron components proved to be immunogenic in PRA but to a far lesser extent than the endothelial cells. A reduction of graft survival from 5 to 4 days was achieved with a cell number of 10(6) cells, and no immunogenic effect (with the exception of mesangial cells contaminated by a small number of macrophages) was observed in smaller cell numbers. The gIFN-treated endothelial cells were more potent than untreated endothelial cells. They reduced the graft survival to 4 days with a cell number of 10(3) and caused a maximal reduction of the survival to 3 days with a cell number of 10(5). The nephron components failed to increase their immunogenicity after 3-day gIFN treatment, regardless of a high increase in their class I and class II expression rates. The study suggests that, in contrast to the endothelial cells, none of the nephron components are able to act as an antigen-presenting cell on their own.