Establishment of murine macrophage hybridoma clones capable of acquiring tumoricidal activity upon activation with recombinant interferon-γ and lipopolysaccharide

Murine macrophage hybridoma clones were established by fusing glycogen-elicited peritoneal exudate cells (glycogen-PEC) derived from C3H/HeN mice and the hypoxanthine-aminopterin-thymidinesensitive murine macrophage cell line, J774.3-2. The macrophage hybridomas were further screened for the capacity to acqurie tumoricidal activity upon stimulation with lipopolysaccharide (LPS) and recombinant interferon-γ (IFN-γ) using murine mammary adenocarcinoma MM48 cells as targets, and three macrophage hybridoma clones, KM-1, KM-2, and KM-3, were established. With concomitant stimulation with LPS, IFN-γ activated these hybridomas dose dependently to exhibit high tumoricidal activity, whereas single stimulation with either INF-γ or LPS, even with higher concentrations, did not activate the macrophage hybridomas. This contrasted with the activation of glycogen-PEC for eliciting tumoricidal activity with a single stimulation with LPS (>1 ng/ml) or IFN-γ (>10 IU/ml). Thus, the macrophage hybridoma clones established here represent inflammatory macrophages which require both IFN-γ and LPS for their activation.