Salivary specific IgG is a sensitive indicator of the humoral immune response to Helicobacter pylori

In humans, salivary antibodies are secreted during humoral immune response. Helicobacter pylori infection is associated with systemic humoral immune response reflected by raised serum levels of specific IgG. The present study was aimed at exploring whether salivary concentrations of specific H. pylori IgG are a reliable indicator of H. pylori infection. Serum and salivary samples were obtained from 291 subjects attending the GI clinic and tested for H. pylori-specific IgG by a direct ELISA (94% sensitivity, 95% specificity for serum determinations) using a crude H. pylori sonicate as antigen. Data are given as optical density (mean +/- S.D.). Levels of salivary H. pylori IgG paralleled those of circulating specific IgG in the 291 subjects studied (0.981 +/- 0.431 vs. 0.777 +/- 0.682, respectively). A significant positive correlation was found between specific H. pylori IgG in sera and saliva samples (r = 0.981, P < 0.0001). An overall concordance between circulating and salivary H. pylori IgG was observed in 238 out of the 291 (81.7%) subjects. Salivary H. pylori IgG represent a sensitive marker of specific humoral immune response and they may substitute circulating H. pylori IgG measurement when sera samples are not available.