IMMUNOREGULATION IN HYPERSENSITIVITY PNEUMONITIS - PHENOTYPIC AND FUNCTIONAL-STUDIES OF BRONCHOALVEOLAR LAVAGE LYMPHOCYTES

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Abstract
The immunologic phenotype and function of bronchoalveolar lymphocytes isolated from 4 pigeon breeders who developed hypersensitivity pneumonitis symptoms on exposure to pigeons, and 6 asymptomatic but equally exposed individuals were examined. Similar numbers of bronchoalveolar lymphocytes were found in symptomatic breeders compared with the asymptomatic, and the percent of T11, T4 and T8 bearing cells as well as the T4/T8 ratios were similar in both groups. Despite these similarities, the groups had significantly different functional activity. Bronchoalveolar lymphocytes from symptomatic breeders demonstrated a marked (P < 0.001) increase in blastogenic activity to both phytohemagglutinin and pigeon serum stimulation when compared with asymptomatic breeders. Enriched bronchoalveolar T-cells suppressed the autologous preincubated peripheral blood lymphocyte response to both phytohemagglutinin and pigeon serum in the asymptomatic compared with the symptomatic breeders. A discrepancy between immunoregulatory T-cell subset phenotype and function in bronchoalveolar lavage lymphocytes may exist in pigeon breeder''s disease. Functional immunoregulatory imbalances play a role in hypersensitivity pneumonitis in pathogenesis.