Biochemical and morphologic changes in a mast-cell neoplasm during treatment with cyclophosphamide.

Treatment of mice bearing the P-815 aseites mast-cell neoplasm produced biochemical and morphologie alterations in the cell population. The metachromasia of cells increased concon fitantly with a rise in serotonin content, while the histamine content of cells remained unchanged. The urinary excretion of 5-hydroxyindoleacetic acid was enhanced, and serotonin was excreted in large amounts in the urine. The excretion of tryptophan metabolites along the kynurenine pathway decreased. The significance of these observations and the usefulness of functional animal tumor systems are discussed. A method for the simultaneous assay of serotonin and histamine content of this neoplasm is described.