Immunoglobulin isotype distribution of locally produced autoantibodies to collagen type I in adult periodontitis

Production of antibodies to collagen type I was analyzed by means of an enzyme-linked immunospot (ELISPOT) assay in patients with chronic adult periodontitis (AP) before and after periodontal hygiene treatment. Anti-collagen type I antibody-secreting cells were found among mononuclear cells enzymatically eluted from inflamed gingiva in 9 of 15 patients with untreated AP and in 4 of 14 hygiene-treated patients with a varied isotype distribution. A notably high prevalence of IgG and IgM isotypes was observed for the anti-collagen antibodies in untreated patients. With wide variation, chronic AP was characterized by a high frequency of spontaneous IgG and low numbers of IgA and IgM-producing cells. Periodontal hygiene treatment significantly reduced the number of IgA and IgM-secreting cells. Although AP is not an autoimmune disease in the accepted sense, our results indicate that local autoimmune reactions to collagen type I are common in untreated AP, implying an interplay between periodontal infection and autoimmunity.