Deposits of immunoglobulins and complement factor C3 in human dental periapical inflammatory lesions

Thirty-five human dental periapical lesions were studied by immunofluorescence technique using polyclonal anti-IgG (F(ab)2), anti-IgM (F(ab)2), anti-IgA (F(ab)2), anti-IgE and anti-C3c as well as monoclonal anti-IgE. Prewashed ethanol-fixed specimens showed a great number of plasma cells staining for IgG. Cells containing IgA, IgM or IgE were also seen. Deposits of immunoglobulins and C3c suggestive of immune complexes were demonstrated using a double staining technique combining FITC-labeled immunoglobulins with TRITC-conjugated C3c. The complexes were located intracellularly in macrophages, as well as in vessel walls and in the basement membrane zone of proliferating epithelium. Immune complexes may be involved in the epithelial proliferation in those granulomas which lead to cyst formation. Monoclonal anti-IgE demonstrated plasma cells and mast cells, as well as intercellular IgE in epithelial strands of granulomas. The role of IgE in the epithelium is obscure. The study strongly indicates the involvement of hypersensitivity reactions type I and III in periapical inflammatory lesions.