The influence of intraperitoneal injections of histamine on tumour growth in fibrosarcoma-bearing mice.

Twenty C57BL/6 male and 20 C3H female mice carrying a methyl cholanthrene-induced fibrosarcoma received, daily, intraperitoneal injections of histamine dihydrochloride (1.8 mg or 6 mg histamine base/mouse). In all histamine-treated C57BL/6 mice, tumour growth was significantly slower than in control mice until day 18. Thereafter, the tumour growth rate of treated compared to control mice was accelerated. In 10 out of 20 C3H mice, tumour growth was significantly slower until day 25; in histamine responsive C3H mice, histological studies showed numerous and large loci of acute haemorrhagic necrosis in the tumours.