CD4 and sarcoidosis: Optimal cell count thresholds for the UIC-Sarcoidosis cohort, obtained with “Youden's index,” suggest that absolute lymphocyte counts ≤1.25 kcells/μL and CD4+ T-cell counts ≤524.5 cells/μL are associated with PET scan positivity with median sensitivity of 51.72 and 68.97% and a median specificity of 82.76 and 72.41%, respectively.