Sulfated glycoconjugate determinants recognized by monoclonal antibody, SG-1, correlate with the experimental metastatic ability of KHT fibrosarcoma cells

Abstract

We have examined the binding and functional activity of monoclonal antibody (MAb) SG-1 that was raised by immunization against embryonal carcinoma cells and screened using KHT fibrosarcoma cells. Quantitative absorption, binding and in situ immunochemical staining assays indicate that the MAb SG-1-defined epitopes are expressed preferentially by the highly metastatic KHT35-L1 cells relative to the weakly metastatic, parental KHTp cells. Furthermore, there was a significant correlation (p less than 0.05) between the expression of MAb SG-1-defined antigen on the cells, following trypsin treatment, and their metastatic ability. Binding of MAb SG-1 to antigen was inhibited by specific sulfated polysaccharides including cerebroside sulfate (brain sulfatide), fucoidan, and dextran sulfate (500 kD) but not by heparan, chondroitin, keratan or dextran (5 kD) sulfates. Initial characterization of antigen from KHT cells indicates that the epitope of MAb SG-1 is defined by sulfated glycoconjugates containing galactose and sulfate but not N-acetylglucosamine. In the total lipid extracts of KHT35-L1 cells the antigen was detected in the delipidated protein fraction as well as in the chloroform/methanol fraction. These results suggest that the sulfated glycoconjugate determinants identified by MAb SG-1 may be relevant to the metastatic process of KHT fibrosarcoma cells.