Collaborative study of bronchial tumour-associated antigens.

Eleven groups of workers submitted a total of 21 bronchial tumour-associated antigen preparations and 19 antisera for comparative studies. Many of the antisera proved to be polyspecific despite absorption procedures. Most of the antigen preparations contained some material reactive towards a reference antiserum to normal human serum proteins. While it appeared that no participants were studying identical antigen-antibody reactions, several cross-reactivities were identified in the antisera. When immune reactions to CEA, AFP, NCA, ferritin, lactoferrin, human pepsin and gastricsin, and the pregnancy proteins, SP1 and SP3 were excluded by use of reference antisera and electroimmunoprecipitation methods, there remained 5 antigen-antibody reactions defining unique antigens. The clinical usefulness of any of these 5 antigens has yet to be determined.