Primary and steroid-induced antibody deficiency in severe asthma: a real-life analysis of a well-defined biologic-treated cohort.

BACKGROUND

Severe asthma is frequently associated with recurrent exacerbations and prolonged systemic corticosteroid use, which may lead to secondary immunodeficiency (SID). In addition, unrecognized primary immunodeficiencies (PIDs) may increase susceptibility to infections and complicate disease management. Data on antibody deficiencies in biologic-treated severe asthma are limited.

OBJECTIVE

To evaluate immunoglobulin levels, the frequency of primary and steroid-induced secondary antibody deficiency, and their clinical associations in patients with severe asthma receiving biologic therapy.

METHODS

This retrospective real-life cohort study included adult patients with severe asthma treated with biologic agents between 2015 and 2024 at a tertiary allergy and immunology center. Serum IgG, IgA, IgM, and IgG subclasses were assessed when clinically indicated. Antibody deficiency was classified as primary or secondary; SID was defined as normalization of immunoglobulin levels after discontinuation of systemic corticosteroids. Demographic characteristics, asthma-related parameters, exacerbation history, corticosteroid exposure, and early treatment response were analyzed.

RESULTS

A total of 146 patients (73.3% female; mean age 52.9 ± 13.7 years) were included. Primary antibody deficiency was detected in 18.3% and steroid-induced SID in 5.8% of evaluated patients. IgA levels differed between biologic treatment groups (p = 0.049), whereas IgG and IgM levels were similar. Immunodeficiency status was not associated with pulmonary function, asthma control, or exacerbation rates during the first three months of biologic therapy. Eosinophil counts significantly decreased after treatment (p < 0.001).

CONCLUSIONS

Antibody deficiencies are relatively common in severe asthma patients receiving biologics. Although immunodeficiency did not affect short-term clinical outcomes, prospective studies are needed to determine long-term impact.