Interactions between vaccinia virus and sensitized macrophages in vitro

The action of peritoneal exudate cells (PEC) from normal and vaccinia virus infected mice on infectious vaccinia virus particles was investigatedin vitro. PEC from immune mice showed a significantly higher infectivity titre reduction (virus clearance, VC) than normal cells. This effect could be clearly attributed to the macrophage. Vaccinia virus multiplied in PEC from normal animals while there was no virus propagation in cells from immunized mice. The release of adsorbed or engulfed virus was reduced significantly in PEC from immunized animals. Anti-vaccinia-antibodies seem to activate normal macrophages to increased virus clearance. This stimulating effect was demonstrable only in the IgG fraction of the antiserum. The activity of macrophages from mice injected three times over a period of 14 days with vaccinia virus could be entirely blocked with anti-mouse-IgG, while PEC from mice injected one time six days previously were not inhibited

Artificial binding of macrophages to syngeneic cells elicits cytostasis but not cytolysis.

Artificial binding of mouse peritoneal macrophages to syngeneic embryonic fibroblasts by means of rabbit anti-mouse anti-macrophage serum or Con-canavalin A inhibited the proliferation of syngeneic target cells without destroying them. It is suggested that an intimate membranal contact between macrophages and target cells triggered cytostasis, whereas cytotoxicity requires an additional step of foreign recognition