Objective To evaluate the effect of bacillus Calmette–Guérin (BCG) as an adjuvant to specific sublingual immunotherapy (SLIT) on the cytokine profile of peripheral blood mononuclear cells (PBMCs) and clinical outcome.
Methods Thirty-two children with asthma and rhinitis allergic to house dust mite (HDM) with negative purified protein derivative (PPD) skin test response were enrolled. After a run-in period of 8 weeks, patients were randomized to receive either SLIT only (n=16) or one dose of BCG immunization before initiation of SLIT (n=16) with a standardized Dermatophagoides pteronyssinus (D. pteronyssinus)+D. farinea 50/50 extract. PPD-negative asthmatics (n=5) allergic to HDM receiving inhaled therapy only were included for comparison of cytokine levels in PBMC cultures. Efficacy was assessed both at the end of run-in and 6 months of treatment periods with criteria including symptom, medication and quality-of-life (QoL) scores, IgE levels, lung function, provocation concentration (PC20), eosinophil count and skin prick tests. IL-4, IL-5, IL-10, IL-12, IL-13 and IFN-γ levels were determined in antigen specifically and polyclonally stimulated PBMC cultures.
Results Both treatment groups showed significant improvement at the end of 6 months for asthma and rhinitis scores and QoL, number of asthma attacks, amount of β2-agonists, inhaled and intranasal steroids, blood eosinophil counts and PC20. Interestingly, phytohaemagglutinin (PHA)-stimulated IL-12 and D. pteronyssinus-stimulated IFN-γ in PBMC were significantly higher in the treatment groups than controls. In addition, IL-12 levels in response to D. pteronyssinus and PHA stimulation were significantly higher in the SLIT+BCG group than the SLIT alone group and controls.
Conclusion The present study demonstrates that successful SLIT is parallel to increased IFN-γ production by PBMC. Although simultaneous BCG vaccination enhanced IL-12 production, it did not additionally improve the clinical outcome.