A modification of the (75Se) selenomethionine assay for the detection of complement-dependent antibody in human tumor systems.

A modification of Brook's prelabeling (75SE) selenomethionine assay was developed and evaluated for detection of complement-dependent antibody (CDA) in a human tumor system. CDA was indeed detected in some breast cancer patients' sera. To determine whether the assay was reliable and reproducible, xenoantibodies were raised in rabbits by immunization with a human breast cancer line, Sk-Br-3, and tested against that line and five other unrelated human cancer lines. Multiple tests were performed on separate days. It can be concluded from the data that the assay is reliable and reproducible. The assay has wide application in investigating the biologic role of complement-dependent antibody activity in human and experimental animal tumor systems.