Interleukin-2-induced growth inhibition of prostatic adenocarcinoma (Dunning R3327) in rats.

The present study was designed to evaluate the effect of a biological response modifier, interleukin-2 (IL-2), on the growth in rats of Dunning (R3327, androgen sensitive) prostatic adenocarcinoma. IL-2 was given to one group of tumour-bearing rats by subcutaneous infusion (Alzet micro-osmotic pump 2002, 14 days) of 424,286 IU/kg per day during 4 weeks. Another group was sham-operated and served as control. Tumour growth was calculated by weekly measurement of tumour volume. IL-2 treatment caused a significant growth delay without any significant toxicity. Plasma testosterone concentrations were similar in both groups and ventral prostatic weights did not differ. Morphometric analyses of epithelial cells, stroma, luminal compartment in tumour tissue and calculation of the number of intratumoral lymphocytes did not show any differences between the two groups. It is suggested that IL-2 treatment can decrease prostatic tumour growth without apparently affecting the testosterone metabolism. Further studies with special interest on the mechanism of action are justified.