This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Chester, S. J. Articles by Hixson, D. C. Search for Related Content PubMed PubMed Citation Articles by Chester, S. J. Articles by Hixson, D. C.

Improved Detection of the Early Stages of Colon Cancer by Determining Both Free Circulating and Immune Complex-bound Antigens Reactive with Monoclonal Antibody¹

Department of Research, Veterans Affairs Medical Center, Providence 02908 [S. J. C., M. P. V.], and Brown University School of Medicine [M. P. V.] and Department of Medical Oncology, Rhode Island Hospital/Brown University, Providence 02903 [Y-P. L., D. C. H.], Rhode Island

The measurement of both immune complex-bound and free unbound tumor-associated antigen was evaluated independently on a panel of sera from colon cancer patients by radioimmunoassay (RIA). A monoclonal antibody (mAb 46.3) raised against secreted antigens from human colon cancer cells in vitro was utilized in the RIA. When circulating immune complexes alone were analyzed, the data demonstrated that 5 of 5 (100%) Dukes' A patients and 11 of 16 (69%) Dukes' B patients had elevated levels of immune complexes reactive with mAb 46.3. Analysis of free circulating antigens demonstrated elevated levels of mAb 46.3-reactive antigen present in 5 of 5 (100%) Dukes' A patients and 15 of 16 (95%) Dukes' B patients. However, by analyzing total reactivity, defined by combining results from RIA with free and immune complex-bound antigen, the sensitivity of detection for Dukes' B increased to 16 of 16 (100%). Total antigen levels in sera from patients with benign diseases (ulcerative colitis, Crohn's disease, adenoma) were not significantly different from normal controls. Analysis of both free and bound antigen in RIA is, therefore, a more sensitive indicator than RIA with immune complex alone. For the advanced stages of disease, only 1 of 5 (20%) Dukes' C and 0 of 5 (0%) Dukes' D sera were positive for reactive immune complexes. When the combined RIA was evaluated, 3 of 5 (60%) and 1 of 5 (20%) Dukes' C and D sera, respectively, were positive with mAb 46.3. Taken together, these results show that RIA with mAb 46.3 is a sensitive indicator for the early stages of colon cancer.

¹ This study was supported by a Medical Research Grant of The Rhode Island Foundation and a Roger Williams Cancer Center Core Grant.

² To whom requests for reprints should be addressed, at Veterans Affairs Medical Center, Department of Research, Building T-20, Davis Park, Providence, RI 02908.

³ These two authors contributed equally to this work.

Received 3/28/94. Accepted 6/14/94.