Introduction: Hypersensitivity pneumonitis (HP) is an immunologically induced lung disease that develops after inhalation of certain environmental antigens only in subjects with susceptibility to antigens. Therefore, both environmental and host immunological factors play important roles in the aetiology and pathogenesis of HP.
Areas covered: Determination of an inciting antigen is crucial for diagnosis, treatment and monitoring. For treatment, modification of the environment and of the host immune response are important. The former includes reduction of antigenic burden (i.e. disinfectant, cleaning), protective devices (i.e. filter, respiratory protection mask, ventilation) and avoidance of inciting antigens. The latter includes corticosteroids, lung transplantation and smoking cessation. For monitoring, measurement of serum Krebs von den Lungen (KL)-6 and surfactant protein (SP)-D concentrations can be used to screen for HP and to detect HP activity. Expert commentary: Measurement of an inciting antigen may be useful to predict the progression and prognosis of the disease. Treatment and monitoring are challenging in chronic HP with fibrosis.
Keywords: CCL17; CCL18; Hypersensitivity pneumonitis; KL-6; SP-D; antigen avoidance; chronic hypersensitivity pneumonitis with fibrosis; corticosteroid; identification of antigen; inhalation provocation test; lung transplantation; measurement of environmental antigen; protective device; smoking cessation.