Assessing immune function in adult bronchiectasis

Abstract

SummaryBronchiectasis is characterized by chronic airway infection and damage and remains an important health problem. Recent literature has emphasized the role of host defence and immune deficiency in the pathogenesis of bronchiectasis, but there have been few studies of immune function in adult bronchiectasis. A comprehensive screen of immune function was conducted in 103 adult patients with bronchiectasis, encompassing full blood examinations, immunoglobulins and IgG isotypes, complement levels, lymphocyte subsets and neutrophil function. Full blood examinations were normal in this cohort, as were complement levels. Statistical analysis confirmed that a significant number of subjects had low levels of IgG3 (13 patients), B cell lymphocytes (six patients) and T helper cell lymphocytes (seven patients) when compared with controls ( P < < < < 0·05). The most common abnormality was found with testing of the neutrophil oxidative burst. All subjects had a normal neutrophil phagocytic function but 33 of the subjects had an oxidative burst that was below the normal range ( P < < < < 0001). Almost half the group (45 subjects) had abnormally low levels of one of these four parameters. The findings of low B cells, Th cells and oxidative burst in bronchiectasis are novel. The results emphasize the importance of immune function assessment for adult bronchiectasis.

Management of bronchiectasis in adults

“…Airway bacterial colonisation occurs because of impaired mucociliary clearance and because of failure of neutrophil opsonophagocytic killing. Since neutrophils from bronchiectasis patients are believed to be normal prior to their arrival in the airway, it is likely that the airway inflammatory milieu itself impairs bacterial clearance [15,16]. Work over several decades has implicate neutrophil elastase in this process.…”

Immunity and bacterial colonisation in bronchiectasis

“…Similarly, King et al 25 showed no major abnormalities in testing of immunoglobulin levels in their cohort. Stead et al 50 also concluded that isolated antibody subclass deficiency was an uncommon cause or association with bronchiectasis in patients beyond the fourth decade.…”

“…In 2006, King et al 25 demonstrated that phagocytosis was normal in patients with bronchiectasis compared with controls, but that oxidative burst was lower. It was suggested this was either due to a suppressive effect of bacterial products on neutrophil function or an intrinsic defect of neutrophil oxidative burst.…”

Bronchiectasis

“…By the way, there is some controversy over whether deficiencies of immunoglobulin G subclasses have a role in the development of bronchiectasis. In a study estimating immune function in adults with bronchectasis, a number of subjects (14%) had low level of immunoglobulin G3, but the significance of this finding was uncertain17. Another small, single center, case-control study showed that almost half (48%) of the patients with bronchiectasis of unknown etiology have low serum concentrations of one or more immunoglobulin G subclasses, and the patients with immunoglobulin subclass deficiency revealed impaired antibody response to H. influenza type b conjugated vaccine18.…”