Cloning and expression of human corneal calgranulin C (CO-Ag)

John D. Gottsch, Sammy H. Liu

Research output: Contribution to journalArticlepeer-review

20 Scopus citations


Purpose. A host-parasite interaction is thought to be involved in the pathogenesis of Mooren's ulcer. We have identified a cornea-associated antigen (CO-Ag), which may be a target for the autoimmune process resulting in Mooren's ulcer. This study presents the cloning, expression, and identification of a cDNA encoding human CO-Ag. Methods. Reverse transcription-polymerase chain reaction (RT-PCR) was performed to amplify a cDNA encoding CO-Ag in the human cornea. The cDNA fragment was cloned into a prokaryotic expression vector and the resulting plasmid was transformed into DH5 E. coli cells. Autoantibody reactivity to the CO-Ag fusion protein in patient sera was tested by Western blots. Results. A cDNA encoding human CO-Ag was amplified by RT-PCR. The entire mRNA coding region was 273 nucleotides in length, predicting a 91-amino acid protein with a molecular weight of 10,683 daltons. The cDNA sequence was identical to human neutrophil calgranulin C (CaGC). Human CO-Ag was expressed in E. coli carrying a plasmid in which the CO-Ag cDNA was under control of the E. coli trc promoter. The CO-Ag fusion protein, which comprised as much as 15% of the total bacterial protein, was purified to 90% homogeneity by affinity chromatography on an immobilized metal column. The recombinant CO-Ag protein produced was recognized by autoantibodies in the sera of 6 of 15 patients with Mooren's ulcer and none of 14 normal control sera by Western blots. Conclusion. CO-Ag is identical to calgranulin C, a neutrophil protein found on the surface of filarial nematodes. A host-parasite interaction may cause autoimmunity to CO-Ag (CaGC) in the cornea resulting in a Mooren's ulcer.

Original languageEnglish (US)
Pages (from-to)870-874
Number of pages5
JournalCurrent Eye Research
Issue number9
StatePublished - 1998


  • Autoantibodies
  • Cornea associated antigen (calgranulin)
  • Molecular cloning
  • Mooren's ulcer
  • S 100 protein

ASJC Scopus subject areas

  • Ophthalmology
  • Sensory Systems
  • Cellular and Molecular Neuroscience


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