Detection of immunoglobulins from explant cultures of periapical lesions

Relative distribution of plasma cells expressing immunoglobulin G subclass mRNA in human dental periapical lesions using in situ hybridization

Immunoglobulin G (IgG)-producing plasma cells are the predominant immunoglobulin secreting plasma cells in human dental periapical lesions, compared with immunoglobulin A- and immunoglobulin M-producing plasma cells. In this study, the cells expressing mRNA, that encoded the distinct IgG subclasses, were detected using an in situ hybridization technique in 25 periapical lesions. These lesions consisted of 14 periapical granulomas and 11 radicular cysts. Four oligonucleotide probes were chemically synthesized from IgG subclass-specific hinge region genes to ensure specificity of the probes. Plasma cells expressing mRNA, which coded for the IgG subclasses, were detected in formalin-fixed/paraffin wax-embedded sections. Background staining was negligible in all of the sections tested. The in situ hybridization method used in this study was both specific and sensitive for the detection of mRNA encoding each of the four distinct IgG subclasses, whereas the cells retained good morphology. The relative proportions of plasma cells expressing each of the IgG subclass-specific mRNAs in both granulomas and cysts were as follows: IgG1 (57.4 and 55.5%); IgG2 (34.1 and 34.6%); IgG3 (4.0 and 4.3%); and IgG4 (4.0 and 5.5%). There were no significant differences between the percentages of plasma cells expressing each of the IgG subclass mRNAs between the two types of lesions. IgG1 producing plasma cells comprised the highest proportion of IgG-producing plasma cells in both types of periapical lesion. IgG2-producing plasma cells were next in abundance, followed by plasma cells for either IgG3 or IgG4, which were in roughly equivalent numbers.

Occurrence of Prevotella nigrescens and Prevotella intermedia in infections of endodontic origin

The occurrence of Prevotella intermedia and Prevotella nigrescens in endodontic infections was studied using sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) of whole cell protein to distinguish between the species. Previous studies have shown an association between black-pigmented bacteria (BPB) and endodontic infections and that Prevotella intermedia (previously known as Bacteroides intermedius) was the most commonly isolated BPB. Recently, however, strains identified as P. intermedia were shown to in fact be composed of two separate species, P. intermedia and P. nigrescens. Fifty-six strains of BPB isolated from endodontic infections and previously identified as P. intermedia were used in this study. Following SDS-PAGE, P. nigrescens showed a unique 18.6 kDa band that was used to differentiate P. nigrescens from P. intermedia. Of the 56 strains of BPB, 41 (73.2%) were identified as P. nigrescens and 15 (26.8%) as P. intermedia. This study confirms that P. nigrescens, and not P. intermedia, is the BPB most often isolated from infections of endodontic origin.

IL-1 alpha and TNF-alpha expression in early periapical lesions of normal and immunodeficient mice

T-helper and B-lymphocytes may contribute to mechanisms that result in bone-resorptive cytokine production in periapical lesion. Mice with severe combined immunodeficiency (scid) lack functional B- and T-cell immunity. The purpose of this study was to investigate the progression of pulp necrosis and the histomorphometric features of periapical lesions in scid vs. normal mice. The expression of the bone-resorptive cytokines IL-1 alpha and TNF-alpha was also investigated. Sixteen five-week-old homozygous scid mice and 14 normal BALB/cJ mice were used. The pulps of mandibular first molars were exposed for 1, 2, 3, or 4 weeks. Blocks of tissue containing the mandibular teeth and supporting structures were processed for both light microscopic examination and immunohistochemical staining for IL-1 alpha dna TNF-alpha. Central sections were randomized, their images were blindly digitized into a computer, and the areas of the lesions surrounding the distal root apices were measured. The cells that stained positively for the cytokines in the same area of adjacent sections were counted. Pulp necrosis progressed at similar rates in teeth from both strains. A progressive and significant increase in the periapical lesion size in both strains was observed. The scid mice lesions were significantly smaller than the controls at only the three-week period. There was heavy cytokine staining in periapical lesions from both strains, especially in areas that contained a mixed inflammatory infiltrate or fibroblasts. The number of positively staining cells was proportional to the lesion size. Therefore, pulpal and periapical pathosis were independent of the presence of functional T- and B-cells in this model.

Immunoglobulins in periapical exudates of infected root canals: correlations with the clinical findings of the involved teeth

This study quantified the concentrations of IgG and IgA in the periapical exudates obtained from 69 single-rooted teeth using enzyme-linked immunosorbent assays, and examined their correlation with clinical findings of the involved teeth. Changes in the levels of these immunoglobulins during root canal treatment were also investigated. The average levels of IgG (85.61 mg/ml) was significantly higher than that of IgA (0.65 mg/ml) (P < 0.001). The exudates from the canals with large lesions (> or = 1 cm in diameter on radiographs) showed significantly higher IgG and IgA levels than small lesions (< 1 cm in diameter) (P < 0.01). The tendency for these to be a decrease in the levels of IgG and IgA was observed following the root canal treatment. These observations suggest that IgG and IgA are involved in the immunopathogenesis of periapical lesions.

Serum IgG reactive with oral anaerobic microorganisms associated with infections of endodontic origin

Numerous species of bacteria have been implicated with infections of endodontic origin. The purpose of this study was to compare the levels of serum IgG antibodies reactive with a panel of 10 oral anaerobic microorganisms implicated in infections of endodontic origin. Serum samples were collected from 4 patient groups that included healthy patients without endodontic or periodontal disease, patients with chronic adult periodontal disease, patients with endodontic disease and patients with combined endodontic-periodontal disease. When Prevotella intermedia was allowed to react with sera from the 4 patient groups, significant pairwise differences were shown between the healthy group and each of the other 3 groups. In addition, there was a significant difference between the periodontal disease group and the combined endodontic-periodontal disease group. When Porphyromonas gingivalis was allowed to react with sera from the 4 patient groups, significant pairwise differences were shown between the healthy group and the periodontal disease group, the healthy group and the combined endodontic-periodontal disease group, the endodontic disease group and the periodontal disease group and the endodontic disease group and the combined endodontic-periodontal disease group. The results of this investigation support other studies that associate P. intermedia with both endodontic disease and chronic adult periodontal disease. The results also support studies that implicate P. gingivalis as a periodontopathogen.