<b><i>Background:</i></b> The role of salivary-specific IgG4 and IgA in subcutaneous immunotherapy (SCIT) is not well defined. We aimed to investigate the change of IgG4 and IgA in both serum and saliva and their correlations with IgE-blocking-factor (IgE-BF) during SCIT. <b><i>Method:</i></b> 307 <i>Dermatophagoides pteronyssinus</i> (DP) allergic rhinitis and/or asthma patients were recruited for this study. 286 patients received DP-SCIT for 1 year. Twenty-one patients received only symptomatic treatment. DP-, Der p 1-, and Der p 2-specific IgE in serum, specific-IgG4 and Der p 2-specific IgA1 and IgA2 in both serum and saliva were measured at timepoints 0, 4, and 12 months during DP-SCIT. Correlation between salivary and serological IgG4, IgA, and their correlation with DP-specific IgE-BF measured in serum was evaluated. <b><i>Results:</i></b> During DP-SCIT, the allergen-specific IgG4 in both saliva and serum increased and correlated significantly, the correlation becomes stronger over the treatment time. DP-specific IgE-BF significantly correlated with DP-specific IgG4 in serum (<i>p</i> < 0.0001) at different timepoints and in saliva at 12 months of SCIT (<i>p</i> < 0.01). No change in Der p 2-specific IgA during DP-SCIT was observed, and the IgA in serum did not correlate with IgA in saliva. There was no correlation between DP IgE-BF and Der p 2-specific IgA in serum or saliva. The control group did not exhibit significant changes in any antibody level measured. <b><i>Conclusion:</i></b> The IgE blocking activity induced by DP-SCIT treatment correlated with specific IgG4 and not IgA. The IgG4 in saliva correlates with serum IgG4 and can be an alternative immunological marker beyond 1 year of SCIT treatment.
Specific immunoglobulin G4 inhibits Th2 cytokine production in allergic asthmatics with Dermatophagoides pteronyssinus subcutaneous immunotherapy
