Influence of smoking and race on immunoglobulin G subclass concentrations in early-onset periodontitis patients

Recent data indicate that smoking is an important risk factor for the development of periodontitis. Smoking is also known to reduce serum immunoglobulin G (IgG) levels. Interestingly, patients with the localized form of early-onset periodontitis (LJP) have elevated levels of serum IgG2, and those who smoke are not clinically different from nonsmoking LJP subjects. In contrast, patients with the generalized form of early-onset periodontitis (G-EOP) who smoke have more extensive destruction than their nonsmoking counterparts. Given the effects of smoking on EOP and the association of IgG2 with less severe disease, we hypothesized that smoking might reduce serum IgG2 and that this might be most apparent in G-EOP. We therefore examined the effects of smoking on serum IgG subclass concentrations in race-matched groups: LJP, G-EOP, and age-matched periodontally healthy controls (NPs). Smoking status was established from serum cotinine levels, and serum IgG subclass concentrations were determined by using radial immunodiffusion. The data indicated that the effects of smoking were remarkably selective with respect to both IgG subclass and race. Smoking did not appear to have any effect on the concentration of IgG1 or IgG3 in either black or white subjects. In contrast, smoking was associated with depressed serum IgG2 concentrations in both white NP and G-EOP subgroups. Serum IgG2 levels in black subjects did not appear to be depressed by smoking, with the single striking exception of the black G-EOP subgroup which also had depressed serum IgG4 levels. The results here confirm that smoking has effects on serum immunoglobulin levels, but the effects were both race and serum IgG subclass specific. Furthermore, the periodontal diagnosis of EOP subjects appeared to be important, as indicated by the fact that IgG2 and IgG4 levels were reduced in smoking black G-EOP subjects whereas the IgG2 and IgG3 levels in black LJP and NP subjects were not reduced by smoking.