Monoclonal antibody reactive with the sialyl-sugar residue of a high molecular weight glycoprotein in sera of cancer patients.

A monoclonal antibody, ST-4-39, was obtained by means of a unique immunization procedure using a gastric cancer xenograft as an immunogen. ST-4-39 reacted immunohistochemically with various cancers and a limited number of normal tissues. The antigen reactive with ST-4-39 was detected in sera of cancer patients, and possessed a molecular weight of greater than or equal to 1 X 10(6). The antigenic determinant was a sialyl-sugar residue different from sialyl-Lewis a recognized by NS 19-9.