This unit describes two protocols that can be used to quantitate interferon (IFN-), an important modulatory lymphokine that regulates natural,
cell-mediated, and humoral
immunity by eliciting a number of biological responses in many different
cell types. Depending upon the specificity of the reagents used, the
assays will detect either human or murine IFN-. The Basic Protocol is an
enzyme-linked immunosorbent
assay (
ELISA) based on IFN-'s unique antigenic structure. The Alternate Protocol is a functional activity
assay based on IFN-'s ability to induce major histocompatibility (MHC) class II antigens (also termed Ia antigens) on responsive
cells. The advantage of the
ELISA protocol is its specificity, while the advantage of the MHC protocol is its sensitivity.