Lymphocyte subpopulations in the peripheral blood of patients with farmer's lung.

The numbers of mononuclear cells having receptors for sheep red blood cells (T lymphocytes) or complement (B lymphocytes) in the peripheral blood of farmer's lung patients were determined. In patients recovering from a clinical episode of farmer's lung or exposed to moldy hay or fodder, both the percentage of T lymphocytes and the T lymphocytes per mm3 were reduced, whereas the number of B lymphocytes remained within normal limits. Farmer's lung patients having no exposure to moldy hay or fodder had T and B lymphocyte numbers similar to a normal population.