Immunoglobulins and complement in the chronic interradicular lesions of the primary teeth.

Eleven unrestorable primary molars with interradicular radiolucencies were extracted. The granulation tissue was curretted from the sockets and examined using immunofluorescence for the immunoglobulins IgG, lgA, and IgM, and the third component of complement. The results demonstrated the presence of IgG in 100%, C3 in 80%, Ig~ in 54.5%, and IgM in 18.1% of the lesions. In an attempt to describe the nature of chronic pulpal infection, several researchers successfully have cultured and identified bacterial strains from necrotic teeth. 1-~ Similar inquiry has been made into the periapical lesions of such infected teeth. Although the literature reports the successful culture and identification of microorganisms from acute abscesses,* most research has shown that microorganisms are not found in chronic periapical granulomas and cysts.5-~ Because these lesions may be sterile and are not grossly infected, a nonmicrobiologic approach to the mechanisms of periapical tissue destruction has been considered by several researchers. 1°-1~ One such mechanism is the humoral immune response. Various components involved in the humoral immune response can contribute to tissue destruction, including anaphylatoxins released during complement fixations, or lysosomal enzyme release from polymorphonuclear leukocytes (PMNs) following attachment by immune complexes. There are several lines of evidence suggesting the participation of immunologically mediated events in the pathogenesis of these lesions. ,7,, 8 Barns and Langeland,19 for example, sealed protein antigens into deep dentinal cavity preparations in monkeys and induced the production of serum antibody. These results suggest that antigens may penetrate through deep carious lesions and contact immunocompetent cells leading to an immune response. In later experiments, Morse and coworkersI~ successfully identified immunoglobulin-producing plasma cells in human periapical granulomas and cysts. They demonstrated the absence of such cells in periapical scars. More recently, Pulver and coworkers is used immunofluorescence techniques to demonstrate the presence of immunologic components within periapical lesions. They demonstrated the presence of the immunoglobulins IgG, IgM, IgA, and IgE, and the complement protein C3 in such chronic lesions. In a similar study by Kuntz and coworkers, ,1 the presence of IgG, IgM, and IgA were observed extracellularly, as well as within plasma cells. IgG-containing plasma cells were most numerous. Positive staining for C3 was found fixed to tissues, suggesting an immunological role. They also found C3 bound to circular structures (resembling blood vessels) in the absence of any detectable antibody, suggesting alternate pathway activation. Endotoxin positively has been identified in periapical lesions. Schonfeld and coworkers20 demonstrated endotoxin in 15 of 20 periapical granulomas, but in only 2 of 10 noninflamed samples. These results have significant implications in the etiology of periapical disease. It is possible that while intact bacteria are not found in significant numbers in the periapical tissues, bacterial products (such as endotoxin) are present in sufficient quantities to trigger host immune mechanisms. Endotoxin, for example, is toxic for several types of cells, including fibroblasts, and also activates the complement cascade via the alternate pathway. The process of bone resorption in periapical pathosis is multifactorial and it is evident that the humoral immune response is one of these factors. The necessity of a thorough understanding of chronic periapical disease can be appreciated from the viewpoint of treatment. Surely, it is advantageous to understand a disease in order to treat it properly and predictably. There is little or no 200 IMMUNOGLOBULINS IN INTERRADICULAR LESIONS: Berryhill et al. literature describing the immunological status of the interradicular or the periapical lesions in the primary dentition. Since it seems reasonable for such a mechanism to exist, it is the purpose of this research to determine if immune components can be identified in the chronic interradicular granulomas of the primary dentition. Methods and Materials Eleven unrestorable, untreated primary molars with interradicular radiolucencies were extracted. The granulation tissue was curetted gently from the sockets and immediately fast-frozen on dry ice. All specimens were kept frozen until processing. Frozen sections four microns thick were prepared with a cryostat-microtome. Representative sections of each lesion were stained with hematoxalin and eosin and submitted for histologic evaluation. The technique for processing the frozen sections has been described by Kuntz and coworkers.11 Sections were fixed for 30 seconds in 90% ethanol and air-dried. The sections then were washed twice in phosphate buffered saline (PBS) for 15 minutes each. Two sections of each specimen were incubated with each of the following fluorescein-conjugated goat antibodies: antihuman IgG, antihuman IgA, and antihuman IgM.o Two sections of each specimen also were incubated with rhodamineconjugated IgG fraction goat antibody to human C3.a Following incubation, each specimen was washed three times in PBS for 10 minutes. (Specimens incubated with different antibodies were not washed in the same baths.) The sections then were air-dried, mounted with buffered polyvinyl alchohol and glycerine, and examined using a microscope equipped with vertical fluorescence illumination and dichroic filter combinations specific for fluorescein and rhodamine. Negative controls consisted of human skin tissue sections which were treated in exactly the same manner as described above. All samples were evaluated as being positive or negative. No attempt was made to quantify the amount of antibody present in the positive samples.