Use of monoclonal antibodies to sialylated Lewisx and sialylated Lewisa for serological tests of cancer.

A new monoclonal antibody, CSLEX1, directed against sialylated Lewisx was tested in parallel with a monoclonal antibody, CSLEA1, directed against sialylated Lewisa antigen. In tests with a solid-phase radioimmune sandwich assay, the sialylated Lewisx monoclonal antibody detected sera from certain cancer patients that were negative with the sialylated Lewisa monoclonal antibody. Some sera from cancer patients showed the reverse reaction. We conclude that the combined use of these two monoclonal antibodies detects a wider range of sera from cancer patients than the use of a single antibody alone. It should be possible in the future to use multiple monoclonal antibodies to increase detection.