TNF and dry eye syndrome: The association between conjunctival epithelial cells and IL6 has been described in many studies: increased expression of IL-1β, IL8, IL6, and TNF-α in conjunctival epithelial cells and tear fluid in the patients with dry eye syndrome [19, 20] and increase of IL-1β, IL8, and, especially, IL6 in impression cytology [21, 22].