THE INFLUENCE OF ZYMOSAN AND INDOMETHACIN ON LIVER AND KIDNEY TUMOR-GROWTH - AN EXPERIMENTAL-STUDY IN RATS

Zymosan, a non-specific macrophage-stimulating agent, modifies favoura bly tumour growth in the liver but has minor effect on renal tumours. The mechanism accounting for variation is still to be clarified. The e ffect of zymosan on liver cancer may be mediated by the macrophage-mon ocyte system. Kupffer cells are in vitro cytotoxic against colon cance r cell lines. The kidney is sparse in macrophage elements. The prostag landin synthesis inhibitor, indomethacin, inhibits tumor growth. In Wi star-FU rats inoculated in the liver and the kidney with an adenocarci noma cell suspension, pretreatment with zymosan (3 mg x 100 g(-1)) sig nificantly reduced both tumour take and liver volume. This effect was attenuated by concomitant administration of indomethacin (0.2 mg x 100 g(-1)). After 2 weeks there was still reduced liver tumour volume. No significant effects on tumour take or growth were observed when the c ells were inoculated into the kidney. There was no significant effect of zymosan on an hepatoma in Lister-Hooded rats. Pretreatment with ind omethacin had no effect on tumor take or initial growth.