Correlation between perchloric-acid-soluble serum proteins, cellular immunity and tumor-cell burden.

Abstract

AbstractSeveral in vitro‐cultured neoplastic cells, particularly human mammary carcinoma and malignant melanoma cells, shed or secrete glycoproteins which are tumorspecific. These compounds contain N‐acetylneuraminic acid (NANA), and they differ from the bulk of serum proteins and glycoproteins in being soluble in perchloric acid. The present studies examined the relation between perchloric acid soluble serum proteins (PA‐proteins), and N‐acetylneuraminic acid (PA‐NANA) and the number of R3230 AdCa implanted into syngeneic Fischer rats. A graded number of R3230 AdCa cells from a mammary rat adenocarcinoma was implanted into separate groups (20 rats/group) of imbred 12‐ to 16‐week‐old female Fischer rats. At 0, 24,48, 72, 196 h, and at 6, 9, 12, 15 and 21 days after tumor cell implantation, blood was examined for protein and NANA levels, and spleen cells for migration inhibition. Vibrio cholerae neuraminidase (VCN)‐treated formalinized tumor cells were used as the antigen. Animals which received 100 R3230 AdCa cells/animal showed a progressive increase in PA‐proteins and PA‐NANA 48 h after implanting the tumor cells. The serum PA‐protein and PA‐NANA levels were time‐dependent and increased with the number of implanted tumor cells. Maximum levels were found in sera from blood drawn 196 h or later from animals which received 1,000 tumor cells/rat or more. At 72 h or more after tumor cell implantation, spleen cells from animals which received 100 or more R3230 AdCa cells per animal were inhibited on contact with VCN‐treated formalinized R3230 AdCa cells. The magnitude of inhibition increased with time and with number of implanted tumor cells. A maximum of 85% inhibition was attained with spleens from animals 196 h after implantation of 100 R3230 AdCa cell/animal, or from animals 72 h after implantation of 103 or 104 R3230 AdCa cells/animal.