Antigenic determinants on B cells of farmer's lung patients.

Peripheral B lymphocytes of 36 HLA typed farmer's lung (FL) patients were tested in a microcytotoxicity assay with 37 sera from multiparous women. The sera had been previously found negative with T lymphocytes from 150 healthy persons. The control groups consisted of 24 healthy spouses of the FL patients, 30 healthy local people, and 58 healthy kidney donors, each HLA typed. B cells from 75% of the FL patients, but only from 25 to 40% of the controls, reacted with six of the 37 sera. Mixed lymphocyte culture tests with lymphocytes of six positive FL patients and their seven HLA identical healthy siblings also revealed antigens on patients' B cells. The reactions are unlikely to be explainable by determinants of the known major histocompatibility antigens.