Role of cell-mediated hypersensitivity in budgerigar breeder's lung.

Eight subjects who possessed precipitating antibodies against budgerigar serum and budgerigar dropping extracts were investigated for the reactivity of their lymphocytes to the antigen. Lymphocytes from the five symptomatic breeders were significantly stimulated by budgerigar serum, but lymphocytes from the three asymptomatic breeders were not stimulated by this antigen, even though both groups showed precipitating antibodies. To investigate the participation of the T-cell response against budgerigar serum, the peripheral blood lymphocytes were fractionated into T-cells, B-cells and monocytes. Only the T-cells responded to the antigen when the monocytes were present. We concluded from these studies that the T-cell-mediated immune response together with a significant contribution from the monocytes plays an important role in the pathogenesis of bird breeder's lung.