CD4 and sarcoidosis: As shown in Fig. 1a, the percentage of freshly obtained pulmonary CD4+ T lymphocytes expressing TL1A was much higher in patients with the active form of the disease (20.3 % ± 6.3), as compared to inactive sarcoidosis (9.4 % ± 4.5 of CD4+ T cells; p < 0.01 vs active disease), and to controls (1.7 % ± 1.5 of CD4+ T lymphocytes; p < 0.01 vs active disease; ANOVA p < 0.01).