I. Reynolds et al., Corneal epithelial-specific cytokeratin 3 is an autoantigen in Wegener's granulomatosis associated peripheral ulcerative keratitis, INV OPHTH V, 40(9), 1999, pp. 2147-2151
PURPOSE. In a previous investigation it was demonstrated that circulating a
ntibodies to a 66-kDa corneal epithelial antigen (BCEA-A) are associated wi
th peripheral ulcerative keratitis (PUK) in patients with Wegener's granulo
matosis (WG). The aim of this study was to identify BCEA-A.
METHODS. The 66-kDa antigen was purified from a bovine corneal epithelial p
rotein extract, using DE52 ion exchange chromatography. Purified protein wa
s used to raise rabbit polyclonal antibodies. These antibodies were used to
screen a bovine corneal epithelial cDNA expression library. Positive clone
s were purified and sequenced. Clones were identified by DNA sequence homol
ogy searches of the GenBank DNA database.
RESULTS. A cDNA clone that demonstrated strong binding to both the rabbit p
olyclonal antibody and patient sera, showed 85% homology to rabbit cytokera
tin 3 (K3). K3 is a basic cytokeratin specific to corneal epithelium. No bo
vine DNA sequence for K3 is available. However, bovine K3 is larger than ra
bbit K3, with a molecular weight of 66 kDa. Immunofluorescence using both p
atient sera and the rabbit antibody demonstrated a cytoplasmic binding patt
ern on human corneal epithelium.
CONCLUSIONS. This evidence suggests that the 66-kDa autoantigen (BCEA-A) as
sociated with PUK in WG is cytokeratin 3, and this may form the basis of a
diagnostic/prognostic test.