THE INDUCTION OF GUT HYPERPLASIA BY PHYTOHEMAGGLUTININ IN THE DIET AND LIMITATION OF TUMOR-GROWTH

The growth of a transplantable murine non-Hodgkin lymphoma tumour, dev eloping either intraperitoneally as an ascites tumour or subcutaneousl y as a solid tumour, has been shown to be markedly diminished by inclu ding phytohaemagglutinin (PHA), a lectin present in raw kidney bean (P haseolus vulgaris) in the diet. In NMRI mice fed PHA within the range 0.45-7.0 mg/g diet, tumours which developed during a 10 day period aft er subcutaneous injection of cells were about 35% of the dry weight of those in lactalbumin-fed (control) animals. The reduced rate of growt h occurred in a dose-dependent manner within the range 0.45-3.5 mg/g d iet. Based on these observations it has been suggested that a competit ion between the gut epithelium undergoing hyperplasia and the developi ng tumour may occur for nutrients from a common body pool, and this ma y be an important factor with regard to the observed initial low level of tumour growth following the feeding of a PHA-containing diet. Obse rvations which showed that the lever of hyperplasia of the small bowel in response to feeding the PHA diets was higher in noninjected mice c ompared to those which had been injected with tumour cells substantiat ed the concept of competition between gut and tumour for nutrients etc . required for growth. Experiments with a second murine tumour cell li ne (a plasmacytoma) in Balb/c mice gave similar results indicating tha t the effect of PHA was not restricted to a single tumour system.