The masking of antigens on trophoblast and cancer cells

Cellular reaction in trophoblastic tumours

The presence of a mononuclear cell reaction to 41 gestational choriocarcinomata, 10 invasive moles and 13 malignant trophoblastic teratomata has been investigated. The intensity of the reaction was graded; there was a significantly better response to therapy and survival rate in those with a "severe" cellular reaction than in those with a "mild" reaction to gestational choriocarcinoma. The pathological and clinical features of invasive moles showed no relationship with the cellular reaction to the tumour. The cellular reaction to trophoblastic teratomata was generally poor but there was a marked cellular reaction to the tumour of one patient who has enjoyed a sustained remission.The relationship of cellular reaction and response to treatment with other histological and clinical features was examined. With the exception of a positive correlation between the degree of vascular invasion and response to treatment, none was found.It is suggested that an infiltrate of mononuclear cells in gestational choriocarcinoma is probably a response to the presence of tumour antigens. The infiltrate favourably affects the response to chemotherapeutic agents, suggesting that it contributes to tumour cell death and it may be interpreted as an immunological response directed at tumour rejection.

Immunotherapy of cancer: immunospecific rejection of tumors in recipients of neuraminidase-treated tumor cells plus BCG

Firmly established methylcholanthrene fibrosarcomas in syngeneic mice will totally disappear if the hosts are treated with living tumor cells that have been exposed to Vibrio cholerae neuraminidase in vitro. The effect is magnified by the simultanieous injection of a nonspecific immunostimulant, BCG. The rejection of the methylcholanthrene tumor is immunospecific and can be induced only with tumor cells, treated with Vibrio cholerae neuraminidase, identical in type with the growing tumor.

Macrophage-melanoma cell heterokaryons. IV. Unmasking the macrophage-specific membrane receptor

Mouse peritoneal macrophages possess a specific plasma membrane receptor for antibody-coated particles. Sheep red cells coated with rabbit 7S antibody attach readily to the macrophage surface and are subsequently interiorized. The fusion of macrophage with nonphagocytic mouse melanoma cells produces heterokaryons in which the macrophage receptor is drastically altered. The receptor is present shortly after fusion and heterokaryons are actively phagocytic. The ability to bind and ingest red cells is, however, progressively lost over the next 12-24 hr and does not reappear thereafter. Exposure of heterokaryons to trypsin (1-100 microg/ml for 30 min at 37 degrees C) results in the reappearance of initial receptor activity and the unmasking of the surface receptor. This property is again lost upon subsequent cultivation. The masking process takes place when cells are cultivated in the absence of IgG so that the adsorption of antibody from the medium is not responsible for this phenomenon. Inhibition of heterokaryon protein synthesis preserves phagocytic activity in a reversible fashion and prevents the masking of macrophage receptors. Inhibition of melanoma RNA synthesis before fusion is also able to block subsequent masking, but is ineffective if delayed until after fusion. Ultraviolet irradiation of the melanoma cell before fusion prevents subsequent masking, whereas similar treatment of the macrophage has no effect. Cells differ markedly in their ability to mask the macrophage phagocytic receptor after fusion. Ehrlich ascites tumor cells mask the receptor rapidly, primary chick fibroblasts minimally, and embryonic chick erythrocytes not at all.

Negative assoication between allergy and cancer

In a survey of 140 patients in the gynaecology wards of a large general hospital, the subjects were asked whether they suffered from any of the common hay-fever type allergies, for example, to flowers, bedding dust, etc. An incidence of 20 per cent was established. Surgical and biopsy reports on this ward population established an incidence of malignant conditions at 28 per cent. These two groups of comparable age turned out to be mutually exclusive.

Reports of pregnancy nausea were also taken. Previous susceptibility to this varied from none to severe, and correlated positively with reports of common allergic type reactions, and consequently, inversely, with liability to gynaecological cancers in later life. The possible significance of this result in the studies of cancer is discussed.