Anti-metastatic effect by in vivo administration of concanavalin A through augmentation of T-derived activated killer activity: Efficacy to B16 melanoma expressed MHC antigen

Abstract

We attempted to investigate if the in vivo administration of concanavalin A (Con A), a potent T cell stimulator, would render anti-metastatic activity in hosts. Assays of activity were performed 20 days after iv inoculation of two clones of the B16 melanoma, B16-H (H-2 +, highly metastatic), B16-L (H-2 −, low metastatic), or 3LL cells into C57BL mice by enumerating lung colonies. In some experiments, hosts treated with anti-asialo GM 1 Ab were used to evaluate effector mechanisms other than NK cells. While the injection of Con A alone had no significant effect on anti-metastatic activity, in nonimmunized hosts the effect by Con A was displayed when the mice were preimmunized with B16-H cells but not in those immunized with B16-L cells. Immunization with B16-H or B16-L cells alone resulted in the generation of killer cells with promiscuous lytic activity and induced an anti-metastatic effect against B16-H, B16-L, and 3LL cells. Con A treatment significantly augmented the killer activity of spleen cells of mice preimmunized with B16-H cells but not of those immunized with B16-L cells. The effectors from mice immunized with B16-H alone or given both Con A and B16-H were mainly of Thy 1 + Lyt 2 + asialo GM1 − cells, on the other hand, those from mice immunized with B16-L cells expressed asialo GM 1 antigen. We showed the efficacy of Con A on the anti-metastatic effect in relation to the host immune response.