How can C3d be measured when it is non-specific to any food?

Antibodies are a part of the adaptive immune system, and C3d is a part of the innate immune system. Measuring both immune system responses captures the most comprehensive picture of immune reactivity. Reaction to the specific food will worsen if C3d activation is present along with an IgG antibody response. The C3d protein attaches to the antigen and amplifies the IgG response, increasing the inflammatory potential of IgG titer.