blood interleukin amount blood interleukin-18 amount VT:0008634 circulating interleukin-18 concentration circulating IFN-gamma inducing factor level The proportion, quantity, or volume in whole blood, serum, or plasma of a cytokine which enhances the cytotoxic activity of NK cells and cytotoxic T-cells and appears to play a role both as neuroimmunomodulator and in the induction of mucosal immunity. circulating IL-18 level circulating IL18 level Trait.ontology EFO:0004581 circulating interferon-gamma inducing factor