[Establishment of rat myelomonocytic leukemia cell line (c-WRT-7)--induction of differentiation and transplantation into syngeneic and non-syngeneic rats].

A long term cultured cell line (c-WRT-7) was successfully established from the transplantable rat myelomonocytic leukemia (WRT-7). Analysis of cell surface markers and phagocytic properties of c-WRT-7 cell showed that about 10% of c-WRT-7 cells differentiated spontaneously from blastic cells to macrophage-like cells in the culture. The differentiation of c-WRT-7 cells was markedly enhanced by in vitro treatment of cells with lipopolysaccharide (LPS), phorbol ester (TPA) and retinoic acid. Of these chemicals, LPS was the strongest enhancer of the differentiation of c-WRT-7 cells over the wide range of doses tested. The transplantation of c-WRT-7 cells into the peritoneal cavity of WKA rat (derived host) proved lethal with a significant increase of blastic tumor cells. Conversely, in SHR rat, which has a common major histocompatibility antigen with WKA rat (RT-1k), although the transplanted c-WRT-7 cells grew well as was observed in WKA rat, increased blastic cells were replaced by the differentiated macrophage-like cells and finally were rejected. Furthermore, the increasing differentiation activity of c-WRT-7 cells in vitro was detected in the peritoneal fluid and serum of SHR rat accompanied by the transplantation of c-WRT-7 cells. This is significantly different from the case of the Fischer rat with a different major histocompatibility antigen (RT-1l) in which transplanted c-WRT-7 cells scarcely grew and were rejected immediately.