FOLATE BINDING-PROTEIN DISTRIBUTION IN NORMAL-TISSUES AND BIOLOGICAL-FLUIDS FROM OVARIAN-CARCINOMA PATIENTS AS DETECTED BY THE MONOCLONAL-ANTIBODIES MOV18 AND MOV19

Folate-binding proteins (FBP), which are molecules relevant in folate metabolism, are overexpressed in ovarian carcinomas, as detected by th e monoclonal antibodies (MAb) MOv18 and MOv19, which recognise two dif ferent epitopes of the gp38/FBP. In this paper, features of the FBP su ch as the distribution on normal tissues and the release in biological fluids of normal and tumour origin have been investigated. Immunohist ochemical analyses on frozen sections of normal tissues showed the pre sence of the gp38/FBP on some epithelia. The reactivity of both the MA b on Fallopian tubes was intense and comparable to that observed on ov ary carcinoma sections. The kidney, bronchial glands, alveolar epithel ium of the lung, oesophagus, stomach, pancreas, breast and thyroid sho wed different levels of staining. By MOv18/MOv19 double-determinant im munoradiometric assay (DDIRMA), the gp38/FBP was found in soluble form in ascitic fluid, serum and urine of nude mice in which the human ova ry carcinoma cell line IGROV1 grew as ascitic carcinomatosis. In human biological fluids, the gp38/FBP was detected in ascites of 60% of ova rian carcinoma patients, and in 29% of those with other carcinomas, bu t not in patients with non-epithelial tumours or with other non-tumora l pathologies. The mean serum arbitrary units (a.u.)/ml values of ovar y carcinoma patients were significantly different to those of healthy donors or patients with endometriosis (P < 0.005 and P < 0.01, respect ively), but not when compared to the sera of lung carcinoma patients. In addition, the sensitivity of DDIRMA was poor, since only 24% of the ovary carcinoma patients were positive with this assay. When a restri cted number of cases selected for the presence of tumour cells in the ascites was examined, the percentage of DDIRMA-positive sera and ascit es rose to 41 and 94%, respectively. In the urine, a strong reactivity was observed in the samples of both normal and tumour origin.