title: Macrophages and resistance to tumours: influence of agents affecting macrophages and delayed-type hypersensitivity on resistance to tumours inducing concomitant immunity.
abstract: Early, specific concomitant immunity to each of four tumours was inhibited by treatment with silica or carrageenan. Late, non-specific concomitant immunity was, with one exception, not inhibited by these agents. Treatment of non-immune mice with silica at certain critical periods before challenge promoted the growth of four of six syngeneic methylcholanthrene-induced tumours in their feet. Treatment with carrageenan was much less effective. Early and late concomitant immunity were inhibited by one or more agents inhibiting delayed-type hypersensitivity: irradiation, niridazole and reserpine. Irradiation of non-immune mice did not effect the growth of tumours in their feet. Treatment of non-immune mice with niridazole or reserpine actually inhibited the growth of some tumours. It is suggested that (a) mice offer some natural resistance to tumour growth, macrophages perhaps being effectors; (b) some tumour isografts may survive only if an inflammatory reaction occurs; (c) mechanisms akin to those of delayed-type hypersensitivity operate in the expression of concomitant immunity; (d) macrophages are important in early, specific concomitant immunity, but perhaps less so in the late non-specific phase.
mesh_terms: D000818:Animals; D002351:Carrageenan / Q000494:pharmacology; D003864:Depression, Chemical; D005354:Fibrosarcoma / Q000276:immunology*; D006968:Hypersensitivity, Delayed / Q000517:prevention & control*; D007109:Immunity / Q000187:drug effects / Q000528:radiation effects; D007113:Immunity, Innate / Q000187:drug effects* / Q000528:radiation effects; D008264:Macrophages / Q000187:drug effects*; D051379:Mice; D009560:Niridazole / Q000494:pharmacology; D012110:Reserpine / Q000494:pharmacology; D012513:Sarcoma, Experimental / Q000276:immunology; D012822:Silicon Dioxide / Q000494:pharmacology
chemical_list: D012822:Silicon Dioxide; D012110:Reserpine; D002351:Carrageenan; D009560:Niridazole