Immune inhibition of allogeneic lymphoma cells in the peritoneal cavity of mice.

Mice were sensitized with cells of normal spleen, transplantable syngeneic lymphomas, or allogeneic lymphomas differing for alloantigens specified by the major histocompatibility complex. From three to eleven days later, the allograft reactivity of these sensitized and appropriate control mice was evaluated in the peritoneal cavity by the disappearance of injected lymphoma cells or the inhibition of DNA synthesis. For the disappearance test, target cells were labeled with [125-I]-5-ido-2'-deoxyuridine before transfer. For the inhibition test, unlabeled target cells were transferred, but these cells were subsequently exposed to the DNA precursor [125-I]-5-iodo-2'-deoxyuridine. In both procedures, cells were recovered from the peritoneal cavity without killing the hosts to measure retained radioactivity. Both tests were immunogenetically specific in detecting secondary allograft reactions, but the disappearance test was less sensitive. By inhibition of DNA synthesis, it was possible to detect primary and secondary reactions, the latter three to eight days after sensitization. Alloantigens associated with the H-2K-Ir regions of Murine Linkage Group IX were more immunogenic than those associated with the Ss-H-2D-Tla regions in eliciting antilymphoma reactions, and female mice responded better than males. It was concluded that the peritoneal inhibition test is sensitive enough to monitor transplantation immunity in vivo and could be applied to animals bearing tumors in sites other than the peritoneum and undergoing chemotherapy.