When an extracellular
dye, Lissamine
green, or 51Cr-labeled spleen cells were injected iv into C3H mice bearing small, partially necrotic 3-methylcholanthrene-induced transplantable
fibrosarcomas (McC3), the
tumor content of these circulating elements per unit weight was substantially lower than that of other selected organs. The level of these blood-borne materials was, however, significantly augmented by the intratumor induction of passive local
anaphylaxis (PLA). The PLA-induced augmentation was inhibited by administration of the
histamine and
serotonin antagonist cyproheptadine; comparable increases were also induced by the intratumor injection of a
histamine and
serotonin mixture or BCG. The weekly intratumor induction of PLA in McC3
tumors resulted in the complete regression of a significant number of the
tumors, and this
therapeutic effect was eliminated by
cyproheptadine treatment. The intratumor injection of BCG induced the regression of approximately 50% of injected
tumors, and the combination of this
immunostimulant treatment with the generation of PLA was more therapeutically effective than either treatment alone. PLA in the vicinity of solid
tumors may, by increasing vascular permeability, potentiate antitumor effector mechanisms, particularly when these are BCG-stimulated. Despite this demonstration of a possible role of
anaphylactic reactions in
tumor immunity, no definitive evidence was found that active
reagin-mediated local
anaphylaxis occurred in C3H mice bearing the McC3
tumor, whether or not they were treated with
immunostimulants.