HLA-C and granular corneal dystrophy type II: Mechanistically, the conventional model of ACD is thought to involve two separate phases: sensitization and elicitation.112 Haptenation of ACD allergens through complexing with cutaneous carrier proteins has been thought to be required for immune recognition, prior to internalization by APCs and presentation via MHC molecules to induce the development of memory and effector T cells.112,113 Subsequent allergenic exposure triggers rapid and heightened inflammation through stimulation of these presensitized T cells.