A NEW APPROACH TO FECAL OCCULT BLOOD TESTING BASED ON THE DETECTION OF HAPTOGLOBIN

BACKGROUND. Colorectal carcinoma is a common disease, occurring in 1 i n 20 adults in Western society, and there is a compelling need for an effective early diagnostic test, Several serum tests, including carcin oembryonic antigen have been used, but none are sufficiently sensitive or specific for the early diagnosis of the disease. METHODS. In a nov el approach using fecal extracts from patients with colorectal cancer as the antigen for immunization, several MoAbs were produced. One (FE1 4.1) was found to react with the feces from patients with colon cancer , but not with those from normal subjects. A sandwich enzyme-linked im munoadsorbent assay was developed, and its ability to diagnose colorec tal carcinoma evaluated. RESULTS. Of the patients with colorectal carc inoma, 91.5% (43/46) were positive compared with 1.9% of normal indivi duals (4/211). Analysis of the N-terminal amino acid sequence of a sub unit of the molecule detected by FE14.1 shows it to be the beta chain of haptoglobin. CONCLUSIONS. The assay developed in this study has sev eral advantages compared with current fecal occult blood tests, includ ing no requirement for dietary restriction and the ability to distingu ish between upper and lower gastrointestinal bleeding, while retaining the sensitivity and specificity of the current tests. Furthermore, th e sensitivity of the tests increases to 100% if the FE14,1 and HemeSel ect are combined. In addition, the study shows the potential to produc e anticancer agents by immunizing with fecal material. (C) 1996 Americ an Cancer Society.