IgG and IgM can activate the classical complement pathway and C5a, C3a, and C4a can trigger inflammation. IgA can activate the lectin complement pathway and the alternative complement pathway and C5a,...IgG and IgM can activate the classical complement pathway and C5a, C3a, and C4a can trigger inflammation. IgA can activate the lectin complement pathway and the alternative complement pathway and C5a, C3a, and C4a can trigger inflammation. IgE can bind to mast cells and basophils and trigger the release of inflammatory mediators.