Crevicular Porphyromonas gingivalis-specific-immunoglobulin A Levels in Healthy and Periodontitis Subjects

Periodontitis, a chronic inflammatory disease common to adults worldwide, is partially mediated by body defense mechanisms, particularly the humoral immune response. Objective: To elucidate an involvement of immunoglobulin A (IgA) in gingival crevicular fluid (GCF) by quantifying and comparing the levels of Porphyromonas gingivalis (Pg)-specific GCF-IgA in healthy and periodontitis groups. Methods: GCF samples were collected twice, with a 5 minute-resting period, from severe generalized chronic periodontitis subjects (n=26) and healthy periodontium individuals (n=22) as controls. GCF at shallow and deep sites of periodontitis group was collected from the same tooth type on contralateral side. The concentration or level (µg/µl) and quantity (µg) of total, Pg-specific and Pg-highly-specific GCF-IgA were then determined by enzyme-linked immunosorbent assay (ELISA). Results: Compared to the primary GCF samples, the secondary ones seem to be less contaminated with salivary IgA because lower levels of IgA were detected (pair t-test, p<0.05). Interestingly, the control group contained significantly higher levels of all types of GCF-IgA compared to the ones of periodontitis group (Mann-Whitney test, p<0.05). Furthermore, within the periodontitis group, relatively higher IgA levels were yielded in GCF samples collected from the shallow sites (Wilcoxon Sign Ranks test, p<0.05). The lowest levels of GCF-IgA were found in samples in the deep sites of the periodontitis group. These data indicate that the levels of GCF-IgA and degree of periodontitis progression seem to be an inverse relationship. Conclusion: This study has supported the hypothesis that the maintenance of high levels of total, Pg-specific and Pg-highly specific IgA in GCF may protect against Pg attack. On the other hand, this non-invasive biological marker may further reflect the challenging degree of this periodontic microbe, the risk of periodontitis development, as well as the successfulness of treatment.