Increased tissue histamine in tumour-bearing mice and rats.

Tissue histamine levels were studied in C3H and C57BL/6 mice bearing a methylcholanthrene-induced fibrosarcoma, in Wag rats bearing an aflatoxin B1-induced hepatoma, and in Commentry rats bearing a grafted hepatoma. Histamine levels were significantly higher (1.5 to 3 fold) in the tumour-bearing animals for ventral and dorsal skin, skeletal muscle and stomach fundus. Total histamine content was increased in the spleen. In C3H mice with McC3-1 fibrosarcoma, the excision of the tumour or its partial regression by intratumoral injections of corynebacterium parvum induced a reversion to normal values. The tumour thus appears responsible for the increased histamine levels in tissues distant from the tumour.