Cytotoxicity of liver macrophages against liver tumours. Influence of betamethasone, indomethacin and allopurinol.

Macrophage activation with zymosan has an inhibitory effect on tumour take and initial tumour growth in the rat liver. 91 rats with syngeneic transplanted hepatoma in the liver were treated with zymosan (46) or saline (45). Betamethasone (glucocorticoid), indomethacin (prostaglandin synthesis inhibitor), allopurinol (oxygen radical scavenger) or saline were administered concomitantly. Tumour take, tumour growth and relative spleen weight were used as in vivo parameters of liver macrophages cytotoxicity and general macrophage activation. Zymosan inhibition of tumour take was counteracted by betamethasone, indomethacin and allopurinol. Betamethasone increased the growth rate of the non-zymosan treated tumours during seven days. Indomethacin decreased the growth rate of the tumours in non-zymosan treated rats up to 14 days. Allopurinol significantly blocked the zymosan inhibition of tumour take and tumour growth after 7 and 14 days. Allopurinol blocked zymosan induced increased relative spleen weight. It is proposed that the liver macrophage cytotoxicity induced by zymosan is in part mediated via production of oxygen radicals.