Whether tear IL-10 is a participant in the local Th2 inflammation or is an attempt to inhibit the pro-inflammatory actions of TNF-α at the ocular surface is not known, and further investigations are needed to clearly define the role of tear IL-10 in human allergic conjunctivitis, as well as the involvement of IL-10 activated mast cells. The gene discussed is IL10; the disease is atopic conjunctivitis.