Non-cytotoxic asialo-GM1-positive cells exert antimetastatic activity

Metastasis can be inhibited by asialo-GM1-positive spleen cells, and in this paper we show that there are two such spleen cell populations. One population is adherent and non-cytotoxic to YAC cells, whereas the other population is non-adherent and cytotoxic to YAC cells. Both cell populations exert an antimetastatic activity in cyclophosphamide-treated mice that are inoculated with LL2 Lewis lung carcinoma cells. We conclude that the antimetastatic activity is not only exerted by cytotoxic asialo-GM1-positive cells (apparently natural killer cells), but also by adherent, non-cytotoxic asialo-GM1+, Thy1.2-, IgG- cells. This means that the latter exert their antimetastatic activity by a non-cytotoxic mechanism.