Increased relative levels of IgG subclasses, mainly IgG3, in patient with bronchiectasis and history of exacerbations; preliminary results from a single tertiary center

Background: Bronchiectasis immunopathology includes Immunoglobulin G (IgG) deficiencies. IgG subclasses have unique profile, showing even a pro-inflammatory role if they are in excess. This aspects is less known in patients with bronchiectasis. Methods: Karolinska University Hospital is a part of the European Multicenter Bronchiectasis Audit and Research Collaboration (EMBARC). We have recruited patients with bronchiectasis in our outpatient clinic using EMBARC methodology and protocol. We retrospectively retrieve data on levels of Immunoglobulins ( IgG, IgG1, IgG2, IgG3, IgG4) and number of exacerbations (verified by antibiotic description) at same year. Results: Twenty patients with IgGs subclasses and antibiotic description (as a marker of active disease) at the same year were included. Median age was 68 years (70% female). The majority of patients had bronchiectasis diagnosis between 5-9 years(55%) followed by those below 5 years (30%) and those between 10-14 years (15%). Mean levels (g/L) of IgG and IgG subclasses were within normal range. In individual basis, two patient had low IgG ( Conclusions: Bronchiectasis, is often correlated with hypogammaglobinemia. Here we shown data that in a small group of patients with active bronchiectasis, there are increased relative levels of IgG subclasses, mainly IgG3. IgG3 is very effective in the induction of effector cells, thus proposing a pro-inflammatory role that needs further evaluation.