Interaction of Bacillus Calmette--Guérin-activated macrophages and neoplastic cells in vitro. I. Conditions of binding and its selectivity

The initial interaction in vitro between Bacillus Calmette-Guérin-activated, peritoneal macrophages from C57B1/6J mice and two nonadherent neoplastic targets (P815 and EL-4) was found to represent firm physical binding of the targets to the macrophages. Binding between the Bacillus Calmette-Guérin macrophages and the EL-4 or P815 targets was greater than that between these two targets and inflammatory macrophages elicited by thioglycollate broth or between lymphocytes and either type of macrophage. Bacillus Calmette-Guérin MΦ also selectively bound three other neoplastic targets (P388, L1210, and RBL-5). The binding, which rose progressively for 60 min of cocultivation at 37 °C, was linear with respect to both the number of interacting targets and macrophages and required the presence of divalent cations and trypsin-sensitive structures on the macrophages. Binding was temperature dependent and required living, metabolically active macrophages. H-2 differences between targets and activated MΦ were not required for binding and did not prevent it. Finally, binding of the P815 targets to the Bacillus Calmette-Gue?in MΦ could be saturated by the addition of excess targets.