IL21 and toxic epidermal necrolysis: We observed significant upregulation of GM-CSF, CX3CL1, IFN-γ, TNF-ɑ, IL-1β, IL-2, IL-4, IL-5, IL-6, IL-8, IL-10, IL-12, IL-17A, IL-21, IL-23, and CCL4 in the tears of SJS/TEN patients at their acute stage compared to those in healthy volunteers (P value < 0.05).