Magne K. Fagerhol

Affiliates

Deparment of Gastroenterology, Ullevaal University Hospital, Oslo, Norway

Abstract

FELISA: A Better and simpler ELISA for fecal calprotectin
Magne K. Fagerhol
Background: Commercial calprotectin kits may give different results; in some samples The Bühlman kits have given about ten times higher values than other kits in some fecal samples. Possible explanations are heterogenic structure of fecal calprotectin, complex formations, decreased number of antibody binding epitopes and variable reaction with different antibodies.
Methods: ELISA kits were obtained from Calpro AS, Oslo. A new method, called FELISA was established based upon th finding that calprotectin, both the purified protein and that in fecal extracts, binds strongly to the plastic in microwells. Coating with capture antibody can therefore be omitted. The amount of bound calprotectin can be assayed by incubation with enzyme labelled anti-calprotectin followed by substrate; the conjugate must be shown to react with all chromatographic subfractions of fecal calprotectin. This method will also detect calprotectin molecules with only one available epitope.
Results: figure A shows a typical FELISA standard curve:

Figure B: comparison of the FELISA with the CalproLab kit.

Conclusions: The FELISA analysis time can be shortened to 40 min. I has a higher sensitivity, particularly in the cut-off region and below.