Advances in the development of a reliable assay for the measurement of stool decay-accelerating factor in the detection of colorectal cancer.
We have previously shown that stool concentrations of decay-accelerating factor (DAF; CD55), a membrane-bound complement-regulatory protein, are significantly elevated in patients with colorectal cancer and that the measurement of stool DAF may be a valuable test for the detection of colorectal cancer. Accordingly, we are working to develop a clinically useful immunoassay for fecal DAF. A requirement for such assay is a plentiful and reliable supply of anti-DAF antibodies. We developed a sandwich enzyme-linked immunosorbent assay (ELISA) for DAF in stool specimens, using two monoclonal anti-DAF antibodies recognizing different epitopes on the DAF molecule. When we first used a biotin-labeled antibody and enzyme-linked streptavidin method, we often observed stool interference, probably due to the presence of a substance(s) with biotin activity which non-specifically bound to the Fc portion of IgG of the first anti-DAF antibody on the ELISA wells. By the use of inorganic salts in the sample-dilution buffer and HRP-labeled anti-DAF as second antibody, we circumvented the stool interference and established that the new ELISA system could reliably measure DAF at low concentrations in stool specimens. Because the new assay system uses only monoclonal antibodies, we can now consistently supply ample amounts of antibodies for routine measurement of stool DAF.
Iwagaki
Naofumi
N
Department of Medicine and Medical Science (Medinen 1). Okayama University Graduate School of Medicine and Dentistry, 2-5-1, Shikata-cho, Okayama 700-8558, Japan.
Mizuno
Motowo
M
Nasu
Jyunichirou
J
Mizuno
Masakatsu
M
Okazaki
Hiroaki
H
Hori
Shinichirou
S
Yamamoto
Kazuhide
K
Okada
Hiroyuki
H
Tsuji
Takao
T
Fujita
Teizo
T
Shiratori
Yasushi
Y
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015703:Antigens, CD; D018958:CD55 Antigens / Q000096:biosynthesis; D016022:Case-Control Studies; D015179:Colorectal Neoplasms / Q000175:diagnosis* / Q000378:metabolism*; D003169:Complement Inactivator Proteins; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods*; D005243:Feces; D005260:Female; D006801:Humans; D008297:Male; D008562:Membrane Glycoproteins; D008875:Middle Aged
D015703:Antigens, CD; D018958:CD55 Antigens; D003169:Complement Inactivator Proteins; D008562:Membrane Glycoproteins