INVITRO EFFECTS OF LIPOPROTEIN-ASSOCIATED CYTOTOXIC FACTOR ON RAT PROSTATE ADENOCARCINOMA CELLS

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  • 1 January 1978
    • journal article
    • research article
    • Vol. 38  (9) , 2956-2961
Abstract
As assayed by the colony inhibition technique, sera from rats at an advanced stage of pregnancy were cytotoxic to a number of tumorigenic and nontransformed cell lines. The cytotoxic effect was not species specific. Primary fetal rat kidney cells wre not susceptible to this cytotoxic effect. The level of demonstrable cytotoxicity in sera rose gradually as gestation advanced; it peaked at 48 h before parturition and disappeared thereafter. Sera from control nonpregnant rats were not cytotoxic. The cytotoxic factor(s) in sera was demonstrable only in the very low-density lipoprotein (VLDL) (hydrated density less than 1.006 g/ml) fraction. Reconstitution studies suggest that inhibitors which usually mask the cytotoxic activity of VLDL in whole serum are present; and pregnancy initiates enhanced VLDL synthesis, which exceeds the masking effect. The possible role of this cytotoxic VLDL in host defense against neoplasia is discussed.