TNFSF13B and hypersensitivity pneumonitis: In sarcoidosis, a positive correlation between disease activity and serum and BALF BAFF levels has been reported.15 16 A link with the TH1 alveolitis is also suggested by the finding that BAFF does not only stimulate B cells but also T cells through BAFF receptors and can augment TH1-associated inflammatory responses.17 18