IgG Subclasses in Bronchoalveolar Lavage Fluid from Patients with Asthma

Abstract

We have measured Immunoglobulin G (IgG) subclasses in serum and bronchoalveolar lavage fluid (BALF) from 12 non-smoking patients with stable asthma and 9 non-smoking healthy volunteers to obtain information on their possible role in local immunological reactions. The quotients (concentration of IgG subclass in BALF)/(concentration of IgG subclass in serum) were calculated. In controls QIgG3 were lower than QIgG1, QIgG2 and QIgG4. The IgG subclasses in BALF and epithelial lining fluid (ELF) from patients with asthma were significantly higher than in controls, mainly due to increased leakage from the blood. Again QIgG3 were lower than Q of other subclasses. In the analysis of local production of IgG, albumin or ceruloplasmin was used as reference protein. Several patients showed a local production or a preferential accumulation of one or more IgG subclasses. We conclude that in healthy persons the IgG subclasses in ELF originate from the systemic circulation by passive permeation. In patients with asthma, the permeability of the respiratory membrane may be increased resulting in increased concentrations of subclasses in lung-lining fluid. In some patients with asthma, an additional local production of IgG subclasses occurs.

IL-33–dependent induction of allergic lung inflammation by FcγRIII signaling

“…Taken together with the fact that inhaled allergens can be contaminated with endotoxins, these 2 signals could augment Th2 inflammation in the lung during secondary responses (19). Intriguingly, this hypothesis is supported by clinical studies that have shown increased IgG levels in the bronchoalveolar lavage (BAL) of patients with asthma due to increased leakage from the blood as well as increased local IgG production (20,21). Furthermore, other studies have identified allergen-specific ICs in the sera of allergic individuals (22).…”

Immunoglobulin levels in bronchoalveolar lavage fluid of children with chronic chest disease

“…There was an increase in IgG-1 and to a lesser extent in IgG-3 in asthmatic patients (Group A). This is in contrast to the findings of Out et al, 9 who found IgG-3 levels lower in BALF of healthy adults compared to their serum concentrations of IgG-3. We have no explanation why IgG-3 levels in that particular study were not increased, since it is well known that IgG-1 and IgG-3 are regulated together.…”

“…27 These differences are probably due to the chronic inflammation at the mucosal level in asthmatic patients, whereas nonasthmatic patients with recurrent infections were examined during infection-free periods; we do not have an explanation for their higher concentrations of IgG-1. Out et al 9 proposed that delayed plasma transudation of IgG-3 was due to its higher molecular mass and shorter half-life compared to the other IgG-subclasses. This led to lower levels of IgG-3 in BALF.…”

“…Although total concentration of IgG has been quantified in bronchoalveolar lavage fluid (BALF) of humans, the contribution of IgG-subclasses to total recoverable IgG protein has been assessed in only a few studies. [9][10][11][12] In adults it is known that the subclasses IgG-1, IgG-2, and IgG-4 are elevated in stable asthma when compared to healthy controls, while IgG-3 is lower. 9 In healthy adults Merrill et al 10 found a good correlation between serum concentrations of IgG-1 and IgG-2 and lavage concentrations, while IgG-4 was found in relatively higher percentage in BALF.…”

Subtle Immunodeficiency in Severe Asthma: IgA and IgG₂ Correlate with Lung Function and Symptoms

“…While IgE levels can be extremely elevated in asthma, the majority of subjects with asthma has serum immunoglobulin levels (including IgE) within the normal range and lacks other symptoms consistent with immunodeficiency [1]. Also, immunoglobulin levels in bronchoalveolar lavage (BAL) or airway lining fluid have been reported to be increased, as would be expected for an ongoing airway inflammatory process [3, 4]. Only a fraction of severe asthmatics have serum immunoglobulins (most often IgG) below normal levels, and this reduction has generally been attributed to steroid therapy [5, 6].…”