SERUM IMMUNOGLOBULIN-G SUBCLASS CONCENTRATIONS IN PERIODONTALLY HEALTHY AND DISEASED INDIVIDUALS

Patients with localized juvenile periodontitis (LJP) often have high t iters of antibody reactive with the serotype-specific immunodominant c arbohydrate antigen of Actinobacillus actinomycetemcomitans serotype b . The vast majority of this A. actinomycetemcomitans serotype b-specif ic antibody is immunoglobulin G2 (IgG2). The present study was underta ken to determine whether the overall total levels of IgG2 in the sera of LJP patients are elevated. WP patients and nonperiodontitis (NP) co ntrols matched for age, race (black and white), and gender were studie d. Additional controls included patients with adult periodontitis (AP) and patients similar in age to LJP patients but with the more-severe, generalized form of early-onset periodontitis (SP). Sera from over 70 0 periodontally characterized subjects were examined by using radial i mmunodiffusion to quantitate IgG2 as well as IgGI, -3, and -4, which w ere included for comparison. Serum IgG2 levels increased with age, and this was most dramatic around puberty. Black subjects in all periodon tal groups had nearly 1 mg more IgG2 per mi than their white counterpa rts. Serum IgG2 levels were elevated (about 30 to 40%) in LJP patients of both races compared with their age- and race-matched NP controls ( P < 0.01). In contrast, SP patients and AP patients had IgG2 levels co mparable to their age- and race-matched NP controls. No other IgG subc lass concentration correlated with periodontal diagnosis except for Ig G3, which was elevated in white LJP patients. We reason that the high levels of serum IgG2 in LJP may be helpful in localizing periodontal d estruction.