Background:
Hypersensitivity Pneumonitis (HP) is an interstitial inflammatory lung disease in response to inhaled antigens. The precise pathogenic mechanism is unclear. The respiratory symptoms include shortness of breath due to restriction of gas transfer suggesting predominantly alveoli involvement. However, the known association HP with bronchial hyper-reactivity and with chronic bronchitis suggests that large airways may be involved also.

Aims and Methods:
Large airway function was evaluated by FEV1 in 50 pigeon fancier and 10 controls and was compared with indices of immune sensitisation to avian antigens.

Results:
IgG antibody to avian antigens was significantly higher in pigeon fanciers with HP compared to those without. There was a significantly reduced decrease in mitogen-driven lymphocyte proliferative response (LPR) in symptomatic pigeon fanciers and this correlated inversely with the antibody titre. The FEV1 was only marginally lower in symptomatic pigeon fanciers compared with those without symptoms. However, the FEV1 correlated significantly with the LPR (r = 0.53, p < 0.001) and the blood CD8+ lymphocyte count (r = -0.52, p < 0.001).

Conclusion:
It has been demonstrated previously that FEV1 decreases with increasing years of avian exposure. This index of large airway function appears to be associated with lymphocyte phenotype and function. These observations support the hypothesis that upper airways are involved, perhaps sub-clinically, in the disease process of HP and that as yet unexplored areas of lymphocyte function may be involved in pathogenesis.

This abstract is funded by: British Pigeon Fanciers Medical Research Trust

Am J Resp Crit Care Med. 2003;167:7,A359