Characteristics of a low‐molecular‐weight factor extracted from mouse tumors that affects in vitro properties of macrophages

Abstract

A dialysable low-molecular-weight factor capable of affecting in vitro properties of macrophages was extracted from four different mouse tumors. This factor not only modulates closely related properties of peritoneal macrophages such as spreading and migration but also inhibits lipopolysaccharde-induced tumoricidal activity of these cells. It can be extracted not only from tumor tissues but also from tumor cells grown in vitro. The appearance of this factor is unique to tumors and it is not present in detectable quantities in normal tissues. The factor from one of the tumors, Lewis lung carcinoma, was purified extensively and the partially purified factor retains all the above effects on macrophages. It is not sensitive to pronase or a mixture of bovine spleen phosphodiesterase II, E. coli alkaline phosphatase and pancreatic ribonuclease. The factor is lipid-like in character and it is soluble in both organic solvents and aqueous media. It has ionizable group(s) and is anionic at neutral pH but non-ionic under acidic conditions.

Interaction between two cellular subpopulations of a rat colonic carcinoma when inoculated to the syngeneic host

“…In other models, progressive tumors have been reported to produce soluble factors able to inhibit tumoricidal activities of T lymphocytes (Hellstrom and Hellstrom, 1970), macrophages (Cheung et al, 1979) and NK cells (Keong et al, 1983), or to prevent accumulation of tumoricidal macrophages at sites of inflammation (Fauve et al, 1974;Snyderman and Pike, 1976;Pasternack et al, 1978). Prostaglandins have been thought to be one of the potential immunosuppressive factors elaborated by progressive tumors (Plescia et al, 1976).…”

Suppression of Lymphocyte Signal Transduction by Murine Mastocytoma Ascites

“…In support of this idea, soluble factors have been isolated from tumorous ascites (3), cell-free tumor homogenates (2,6), and tumor cell culture supernatants (7,10). Among them the tumorderived suppressor factors from mouse P815 mastocytoma, a parental line of PI .HTR, have been well studied (3,4,6,7,16).…”

“…Despite considerable evidence for the existence of tumor suppressor factors that inhibit a number of immunological events, such as macrophage tumoricidal activity (2), in vitro antibody response to sheep red blood cells (SRBC) (6,10,16) and alloantigen-or mitogen-stimulated lymphocyte proliferation (3,4,10), all of the earlier studies concerned the late effector phase of immune responses, and much remains unknown about both the mechanism through which and cellular and molecular sites at which these suppressor factors affect immune responses. (14), P815 mastocytoma, and L1210 leukemia of DBA/2 mouse origin (H-2d) were used for producing the tumorous ascites.…”

Macrophage Migration Stimulation Factor

“…Mouse tumours appear to produce a low molecular weight substance that alters macropbage function [11]. This factor stimulates in vitro migration, inhibits slow spreading, and inhibits tumoricidal activity.…”