Primary antibody deficiencies represent an underestimated comorbidity in asthma patients: efficacy of immunoglobulin replacement therapy in asthma control.

Objective: Primary antibody deficiencies (PAD) are an underestimated comorbidity in asthma and its treatment could improve disease control.

Methods: a retrospective cohort of asthmatics, affected by IgG subclass deficiency or unclassified antibody deficiency and treated with low-dose intravenous immunoglobulin replacement therapy (IRT) was recruited. Demographic and clinical data, chest CT scan, blood eosinophils, atopy, chronic oral corticosteroid (OCS) therapy were evaluated at baseline. Asthma exacerbations, lower respiratory tract infections (LRTI), upper respiratory tract infections (URTI) and asthma-related hospitalizations were assessed after one and two years of IRT.

Results: 57 moderate-to-severe asthmatics were enrolled, mostly affected by T2 low asthma (39/57, 68.4%). After one year, IRT was effective in improving, irrespective of bronchiectasis, atopy, eosinophils and PAD type: 1) trough IgG (826.9 ± 221.3 vs 942.2 ± 195.1 mg/dl;  < 0.0001) and IgG subclasses (IgG1 355.4 ± 88.4 vs 466.7 ± 122.3,  < 0.0001; IgG2 300.1 ± 130.1 vs 347.6 ± 117.3,  < 0.0005) serum levels. 2) asthma exacerbations (6.4 ± 4.1 vs 2.4 ± 1.9,  < 0.0001), LRTI (4.3 ± 3.9 vs 1.3 ± 1.5,  < 0.0001) and hospitalization rate (0.26 ± 0.7 vs 0.05 ± 0.2,  < 0.01). These results persisted after 2 years of therapy. Estimated mean cumulative OCS exposure was reduced by 4500 mg over the 2-year period.

Conclusions: low-dose IRT is effective in improving asthma control and lessening OCS burden in asthmatics affected by PAD.