Tumor cell origin of histaminase activity in ascites fluid from patients with ovarian carcinoma

We have demonstrated by tissue assay and immunohistochemical techniques that tumor cells appear to be the source of the increased histaminase activity found in 60% of ascitic fluids from patients with ovarian carcinoma. The histaminase activity in 64% of tumor tissues studied was greater than 100 U/g of tissue, a value higher than that for normal tissues other than kidney and intestine. The presence of elevated ascitic fluid histaminase activity (greater than 3.5 U/ml) correlates with the presence of high histaminase activity in tumor tissue. Histaminase activity is higher in ascitic fluid from the patients than it is in their plasma, probably reflecting the direct entry of histaminase into the peritoneal cavity.