Chapter 12 Immunodeficiencies associated with bronchiectasis

Bacterial infection of the lung is a cause of bronchiectasis and also the main clinical problem in patients with bronchiectasis. As a consequence, inherited or acquired immunodeficiencies that allow repetitive lung infection with respiratory pathogens (such as Streptococcus pneumoniae and Haemophilus influenzae) can drive the development and progression of bronchiectasis. The immune defects most strongly associated with bronchiectasis are those resulting in hypogammaglobulinaemia. These include the primary immunodeficiencies, common variable immunodeficiency and X-linked agammaglobulinaemia and the secondary immunodeficiences caused by lymphoproliferative malignancy, allogeneic bone marrow transplantation and chemo/immunotherapy. Identifying hypogammaglobulinaemia is important and allows patients to be given immunoglobulin replacement, reducing exacerbation frequency and probably progression of bronchiectasis. Conditions resulting in T-cell dysfunction (such as chronic HIV infection or immunosuppression), reduced bacterial opsonisation (such as complement deficiencies), failure of phagocyte migration (leukocyte adhesion deficiency) and impaired intracellular killing of bacteria (chronic granulomatous disease) may also predispose to bronchiectasis. In this chapter we describe the main immunodeficiencies associated with bronchiectasis and suggest a staged approach to immunological investigations.