Peripheral blood NK cells in patients with extrinsic allergic alveolitis: phenotype and function

Peripheral blood mononuclear cells obtained from patients with extrinsic allergic alveolitis were tested with a series of monoclonal antibodies against natural killer cells, including HNK-1, NK-15, Ab8.28, OKM1 reagents. An NK in vitro functional evaluation of these cells was associated to the phenotypic analysis. Our data demonstrated an increase, with respect to controls, of the percentage and absolute number of HNK-1 positive cells in the blood of these patients. This increase was consistent with an enhanced cytotoxic in vitro activity. These findings provide evidence that in patients with extrinsic allergic alveolitis, the exposition to antigenic stimuli triggers the NK system. Possible immunopathogenetic mechanisms, especially in comparison with other interstitial lung disorders, are discussed.