Purpose To judge the expression patterns of cytokeratin (K) 12 13 and 19 in normal epithelium of the human ocular surface to determine whether K13 could be used as a marker for conjunctival epithelium. of K12 K13 and K19 was confirmed by immunostaining with specific antibodies on histologic sections of human sclerocornea that contained the conjunctiva limbus and cornea and on impression cytology (IC) specimens of the cornea and conjunctiva from normal donors. Double staining of K13/K12 and K19/K12 on histologic sections and IC specimens was performed. Results There were 337 transcripts that were preferentially expressed in the conjunctiva. and were among the top twenty transcripts RAC1 in the conjunctiva and this preferential expression pattern GS-7340 of and was confirmed by qRT-PCR. Immunohistochemical studies showed that K13 was expressed at the posterior limbal epithelium and conjunctival epithelium but was totally absent in the cornea. K12 was expressed in the corneal and anterior limbal epithelia except for the basal layer and was absent from the conjunctiva. In contrast K19 was detected in the corneal conjunctival and limbal epithelia. Immunostaining from the IC specimens demonstrated K12+ epithelial cells in the corneal area K13+ cells in the conjunctival region and K19+ cells in the corneal and conjunctival specimens. Appearance of K13 and K12 in the ocular surface area was mutually distinctive on both histologic and IC examples using dual immunostaining. Conclusions K13 is certainly more specific towards the conjunctival epithelial cells than K19 and possibly could be utilized being a marker to recognize conjunctival epithelial cells in limbal stem cell insufficiency. Launch The ocular surface area is lined with the conjunctival and corneal epithelia. Despite having different phenotypes and histogeneses both epithelia type a continuous level and work as barriers to safeguard the ocular surface area from injury infections and desiccation. The individual corneal epithelial stem cells (limbal stem cells [LSCs]) are presumed to find in the limbus ie the transitional area between your cornea as well as the conjunctiva plus they keep up with the homeostasis of corneal epithelial cells [1 2 When LSCs are broken or lacking the conjunctival epithelium invades the GS-7340 corneal surface area which invasion qualified prospects to corneal opacity and neovascularization . This conjunctivalization process in the corneal surface impairs vision and causes blindness by the end stage  severely. Medical diagnosis of LSC insufficiency (LSCD) is manufactured by clinical evaluation and verified by impression cytology (IC) GS-7340 . The current presence of goblet cells in the presence is indicated with the cornea of conjunctival epithelium. Yet in many ocular disorders where LSCD is certainly noticed goblet cell insufficiency also coexists which coexistence qualified prospects to a false-negative result. Egbert et al.  discovered that it is challenging to tell apart conjunctival epithelia from corneal epithelia by regular cytology methods. The identification of the marker that’s portrayed in the conjunctival epithelium however not in the corneal epithelium is a developing need. Good applicants are cytokeratins which comprise a family group of intermediate filament cytoskeletal proteins in epithelial cells and so are divided into the sort I (acidic) and type II (simple to natural) subfamilies. Cytokeratins type filaments in charge of the integrity from the epithelial cell framework and for their different patterns of appearance these proteins could possibly be utilized as differentiation markers . The corneal epithelium however not the conjunctival epithelium expresses cytokeratin (K) 12 . Although K19 was proposed by Donisi et al initially.  as a particular marker of conjunctival epithelial cells and utilized by others to diagnose LSCD various other groups discovered that K19 isn’t particular to conjunctival epithelial cells GS-7340 since it is certainly portrayed in corneal epithelial cells as well [10-12]. Barbaro et al.  recently compared K12 and K19 expression in both sclerocorneal tissues and IC specimens and their results confirmed the previous finding that K19 is not specific to conjunctival epithelial cells. A more specific marker of limbal and conjunctival epithelia would be necessary to detect non-corneal epithelial cells around the corneal surface. To search for conjunctival specific marker(s) we first performed preferential gene profiling in the conjunctiva in direct comparison to that in the cornea using microarray technique. and transcripts were among the GS-7340 genes preferentially expressed in the human conjunctiva and their expression levels were confirmed.