sentences:  Ig is a class of antibody found only in mammals that plays an important role in allergy response and defense against many kinds of pathogens by protecting the body against them by complement activation, opsonization for phagocytosis, and neutralization of their toxins.IL-4 and IL-10 have both been shown to reduce the production of metalloproteinases (endopeptidases which break down collagen and other extracellular proteins) by human AMs.IL-4 has dual effects upon macrophage biological function, which may be either stimulatory or inhibitory.