Immune components in human dental periapical lesions.

Immunofluorescence techniques were used to investigate perlapical lesions for the presence of components indicative of hypersensitivity reactlons medlated by humoral factors. In periapical granulomas, IgG, IgA, IgM and IgE cells represented 70, 14, 4 and 10 per cent, respectively, of the immunoglobulin-containing cells (ICC) observed. Intact and apparently degranulating mast cells were seen in the vicinity of the IgE ICC. Thus, components required for anaphylactic-type hypersensitivity were present in these lesions. The connective tissue of unwashed periapical granulomas stained intensely for IgG but less so for IgA and complement (C,). Prewashing failed to eliminate this staining which suggested that a portlon of these components were bound to tissue. Quick-frozen sections showed enhanced C, fluorescence both of connective tissue and of structures resembling small blood vessels. The potential therefore also exists for antigen-antibody complex-type hypersensitivity in this type of lesion. Radicular cysts showed a different pattern of fluorescence in that both IgG and IgA represented 45 per cent of the ICC, whereas IgM and IgE ICC each represented 5 per cent of the ICC. Only ant+IgG tissue fluorescence was noteworthy in cystic tissue. The one periaplcal scar examined revealed no cellular or connective tissue staining. Thus, periaplcal tissues can contain the components necessary for host immunopathologic responses. These responses may participate in the development of periapical pathosis.