IgG subclass deficiencies associated with bronchiectasis.

Abstract

Only a small number of patients with IgG subclass deficiencies (IgGSD) have been observed to have bronchiectasis. Moreover, in the series of patients with bronchiectasis, IgGSD have not been found at any frequency, and the etiology of bronchiectasis remains unclear in 29 to 49% of cases. Serum concentrations of total IgG, IgA, and IgG subclasses as well as pulmonary function were measured in 65 patients (aged: 10 to 74 yr) with bronchiectasis of unknown etiology. An ELISA test was performed to quantify subclasses 1 through 4 using subclass-specific antihuman monoclonal antibodies. IgG subclass estimation in a healthy population with age-stratified normal ranges was derived from 100 adults, 37 children aged between 10 and 12 yr, and 27 adolescents aged between 13 and 16 yr. Serum concentrations of specific IgG antibodies to Haemophilus influenzae type b capsular polysaccharide (Hib-PRP) were also assayed by an ELISA test in 19 of the patients (10 with IgGSD and nine with non-IgGSD) and in 58 healthy individuals before and 3 wk after immunization with Hib-PRP conjugated to meningococcal outer membrane protein complex (OMPC). Thirty-one patients (48%) had low serum concentrations of one or more IgG subclasses (19 IgG2 deficiencies, 2 IgG3 deficiencies, 3 IgG4 deficiencies, and 7 combined subclass deficiencies). All patients showed increased levels of total IgG, IgG1, and IgA, but this rise was significantly higher in patients without IgGSD. Patients with IgGSD showed impaired antibody response to Hib-PRP compared with patients with non-IgGSD and the control group. IgGSD, particularly IgG2 deficiency, are not an unusual cause of bronchiectasis. Therefore, serum levels of IgG subclasses must be assayed whenever other causes of bronchiectasis have been ruled out.

An Investigation into Causative Factors in Patients with Bronchiectasis

“…We only ascribed severe IgG subclass deficiency to values that fell outside the entire range found in healthy persons, and the low incidence of significant IgG subclass 1, 2, or 3 deficiency in our study (1 patient, Ͻ 1%) is similar to that found in others using the same criteria (2%) (21). Another study using less stringent control data reported a higher incidence of IgG subclass deficiency (48%) (38). Patients found to have only borderline low IgG subclass levels were not classified as immunodeficient unless they had evidence of a functional defect as well, determined by a defective response to immunization.…”

A Review of Non-Cystic Fibrosis Pediatric Bronchiectasis

“…By measuring antibody response to Haemophilus influenza type-b capsular polysaccharide vaccine, they found 48% with deficient responses and low levels of one or more IgG subclasses. Of the 31 with diminished IgG responses, 19 had IgG2 deficiency, two had IgG3 deficiency, three had IgG4 deficiency, and seven had combined subclass deficiencies [16]. Of the 225 children with chronic sinopulmonary infections evaluated by Ozkan et al, 19.1% were found to have antibody deficiencies.…”

Infectious and Noninfectious Pulmonary Complications in Patients With Primary Immunodeficiency Disorders

“…IgG subclass deficiency, particularly that of IgG2, has been associated with bronchiectasis in children [77]. Given that the incidence of bronchiectasis in patients with IgG subclass deficiency varies widely (anywhere from 4% to nearly 50%), it is difficult to establish a correlation between bronchiectasis and IgG subclass deficiency [65,69,[77][78][79]. In one study, SAD was reported in 58% of patients with idiopathic bronchiectasis [80].…”