PURPOSE. In a previous investigation into corneal autoimmunity, it tvas dem
onstrated that a putative autoantigen, a protein of 66 kDa, present in bovi
ne corneal epithelium, binds circulating autoantibodies in approximately 60
% of patients with Wegener's granulomatosis (WG). The aim of the present st
udy was to characterize and identify the 66-kDa protein.
METHODS. A purification protocol was established for the 66-kDa protein usi
ng standard chromatography techniques. During the purification procedure it
became clear that the 66-kDa protein detected in patients' sera was in fac
t two proteins, both running at 66 kDa on sodium dodecyl sulfate-polyacryla
mide gel electrophoresis, that eluted in different fractions on DE-52 chrom
atography columns. These two proteins have been labeled bovine corneal epit
helial antigen-A and -B (BCEA-A and BCEA-B). Further investigations of anti
body binding have demonstrated that patients' sera bind to either one or th
e other of these proteins with no cross-reactivity between them. Separated
BCEA-A and BCEA-B protein extracts were immunoblotted with 27 WG patients'
sera, 10 Churg-Strauss syndrome (CSS) patients' sera, 31 rheumatoid arthrit
is (RA) patients' sera, and 40 healthy control subjects' sera from the bloo
d bank.
RESULTS. Forty-six percent of WG patients' sera had antibodies to one of th
e 66-kDa antigens, whereas none of the healthy control subjects' sera had 6
6-kDa antibodies (P < 10(-5)). In the WG group, 31% were positive to BCEA-A
(versus controls, P = 0.0023), and 15% were positive to BCEA-B. WG patient
s with peripheral ulcerative keratitis (PUK) had a significant association
with anti-BCEA-A antibodies when compared with healthy control subjects (50
%, P < 10(-6)). However, in the RA group with no eye disease there was an a
ssociation with BCEA-A (25%, P = 0.011) but not in the RA group with PUK. T
he frequency of anti-BCEA-B antibodies was significantly increased in patie
nts with CSS (60%, P < 10(-7)).
CONCLUSIONS. In summary, it has been shown that vasculitis patients have an
tibodies to two 66-kDa corneal antigens and that autoantibodies to these an
tigens are mutually exclusive. It has also been shown that antibodies to BC
EA-B are associated with CSS, whereas BCEA-A antibodies are associated with
WG and RA.