IL4 and oral lichen planus: In this study, although expression of the Treg-type cytokine (IL-10) was detected in the lymphocytic infiltration of lamina propria from GS and OLP patients, expression of the Th2-type cytokine (IL-4) and the Th17-type cytokine (IL-17) was detected in the OLP patients, but not the GS patient.