Correlation of serum vitamin D concentration with humoral-specific IgG2 and IgG4 levels in high responders to immunotherapy with a 300 IR sublingual house dust mite tablet

This study involves house dust mite (HDM)-allergic individuals enrolled in a double-blind, placebo controlled clinical trial of a 300-IR sublingual HDM tablet. It shows that the pretreatment serum concentration of vitamin D is not predictive of the clinical response to sublingual immunotherapy (SLIT). On this basis, vitamin D cannot be considered a biomarker of the outcome of SLIT to HDM. However, in those individuals who highly respond to SLIT, the pretreatment serum concentration of vitamin D correlates with the clinical outcome. Moreover, it correlates with the serum concentrations of HDM-specific IgG4 and IgG2 before and/or after treatment. Such correlations are not observed in low responders to SLIT. Overall, this study points to a previously evidenced specific behaviour of immune responses in high responders to SLIT.