Although none of these included patients with fibrotic disease, Liaoet al. [59] showed, in the first published single-cell transcriptomic data on BAL cells from sarcoidosis patients, that those with progressive compared to nonprogressive sarcoidosis (n=2 each) had increased expression of five genes in their macrophages, three of which were major histocompatibility complex (MHC) II alleles, namely, human leukocyte antigen (HLA)-B, HLA-DQA2 and HLA-DRB5. The gene discussed is HLA-DRB5; the disease is sarcoidosis.