Phytohemagglutinin-induced gut hyperplasia and the growth of a mouse lymphosarcoma tumor

NMRI mice injected subcutaneously with Krebs II lymphosarcoma cells and fed on a diet containing the kidney bean lectin phytohemagglutinin (PHA) within the range 0.45-7.0 mg/g diet, developed tumors during a 10 day period which on average were only 35% of the dry weight of tumors in lactalbumin (La) fed mice (control). The reduction in growth occurred in a dose-dependent manner in the range 0.45-3.5 mg/g diet. The degree of hyperplasia of the small intestine in response to feeding the PHA diets was higher in non-injected compared to injected mice. A lipolytic effect of PHA was observed above 1.75 mg/g diet in control mice and the highest concentration had a major effect on body weight. Since the index of hyperplasia at the lowest PHA concentration tested did not correlate with the reduction in tumor size, it is suggested that other factors in addition to the initial lectin-induced gut hyperplasia are involved in slowing down the progression of tumor growth.