Development and validation of an enzyme-linked immunosorbent assay (ELISA) for recombinant human gamma interferon

A one-site ELISA for the quantification of recombinant human gamma interferon (rh-IFN-gamma) was developed and validated. A single monoclonal antibody (Mab) was used as a "catching" antibody and as a horseradish peroxidase (HRP)-labeled conjugate. Detection limit and quantification limit of this assay were estimated to be 1.26 and 15 ng/mL, respectively, and the coefficient of variation was below 15%. The ELISA was specific for rh-IFN-gamma, showing no cross reactivity to other related molecules in the range of the concentrations studied. The results correlated well with those obtained by a bioassay method. By using this assay, it was demonstrated that 0.01-1% (v/v) Tween 80 protected rh-IFN-gamma during freezing and thawing.