title: [Concomitant antitumor resistance].
abstract: Concomitant resistance of tumor-bearing mice against a second tumor challenge was evaluated in euthymic and athymic mice using 17 tumors with different degrees of immunogenicity. Two temporarily separated peaks of concomitant resistance were detected during tumor development: the first peak was only observed associated with small immunogenic tumors (< 500 m3., it was tumor-specific and mediated by T cell-dependent immunological mechanisms. The second peak was exhibited by large tumors (> 2000 mm3) independently of their immunogenicity; it was non-tumor specific, thymus-independent and correlated with a serum-activity (neither antibodies nor complement) which inhibited the in vitro proliferation of tumor cells. Out of 17 tumors studied, 15 tumors exhibited a moderate or strong concomitant resistance. The remaining two, which exhibited a weak or undetectable concomitant resistance and correlatively, a low or absent serum-inhibitory activity were the only tumors which included lung metastases. This fact suggested a correlation between concomitant resistance, absence of metastases and the existence of an inhibitory factor(s) in the serum. This inhibitory factor was partially characterized: it was resistant to boiling (5-10' at 100 degrees C) and to variations of pH; its molecular weight was estimated between 850 and 1200 D; it was recovered in only one fraction from HPLC (high power liquid chromatography) columns presenting maximum absorption at 215 and 266 nm; amino acid analysis and magnetic nuclear resonance studies suggested the presence of a molecule of thyrosine and one or two molecules of carbohydrates in its structure.
authors.affiliation: Instituto de Investigaciones Hematológicas, Academia Nacional de Medicina, Buenos Aires, Argentina.
authors.forename: R A
authors.initials: RA
authors.lastname: Ruggiero
authors.forename: P D
authors.initials: PD
authors.lastname: Di Gianni
authors.forename: M
authors.initials: M
authors.lastname: Franco
authors.forename: O D
authors.initials: OD
authors.lastname: Bustuoabad
mesh_terms: D000818:Animals; D007113:Immunity, Innate; D051379:Mice; D008819:Mice, Nude; D009362:Neoplasm Metastasis; D009368:Neoplasm Transplantation / Q000276:immunology; D009369:Neoplasms / Q000097:blood / Q000276:immunology* / Q000473:pathology