IL17A and sarcoidosis: Another subset of CD4T-lymphocytes, involvement in granuloma induction or maintenance in sarcoidosis are Th17 cells, as documented by the elevated numbers of IL-17, IL-22 and IFN-γ secreting CD4T-lymphocytes found in the blood of patients with sarcoidosis, as well as an increased proportion of Th17 cells, located in and around sarcoidal granulomas [127, 144, 151].