Alpha 2-macroglobulin in gingival fluid: correlation with alveolar bone loss in periodontal disease

The concentration of total, free and bound (complexed forms) of alpha 2-macroglobulin was measured by crossimmunoelectrophoresis in patients with different degrees of periodontal disease as indicated by the gingival index (GI) and the proportion of alveolar bone loss (ABL). The concentration of total alpha 2-M (bound and free forms) is lower in gingival fluid taken from sites with more inflamed gingivae. Its concentration decreases with an increase in the pocket depth and the alveolar bone loss at the sites of fluid collection. The concentration of alpha 2-M bound form, i.e., the presence of alpha 2-M: protease complexes, in gingival fluid is low or absent at the sites with more pronounced bone loss (above 15%). Our results support the hypothesis that unbalanced protease activity damages the periodontal tissue. Not only the proteolytic but also inhibitory activities are altered and correspond to the severity of the disease.