MUC1 glycoprotein expression in non–dry eye and dry eye. Filter membranes prepared by impression cytology were stained with PAS and the mAb KL-6. Sections (5 μm) were prepared from filters of non–dry eye conjunctiva (
A,
B). The membrane filter primarily picked up superficial cells (
B,
arrows) and absorbed secreted mucin (
A,
B,
arrowheads), and occasionally whole goblet cells (
A,

). Note that the mAb KL-6 did not label goblet cell mucin. Rose bengal–stained bulbar conjunctival epithelia (
C,
small arrowheads) in moderate dry eye are weakly stained by mAb KL-6 (
D), but were still PAS positive (
E). Non–dry eye corneal epithelium (
F) was weakly stained by the mAb KL-6. A prominent mosaic pattern of KL-6 was observed in the corneal epithelium of moderate (
J) and severe (
L) dry eye and a weak mosaic pattern of KL-6 was observed in mild dry eye (
H). In bulbar conjunctival epithelium, a honeycomb pattern was seen in non–dry eye (
G); a mosaic pattern without strong positive cells in mild dry eye (
I); a mosaic pattern with strong positive cells in moderate dry eye (
K); and only a few weak positive cells in severe dry eye (
M). PAS-positive mucin secreted by goblet cells was observed in non–dry eye (
G), only a few in mild dry eye (
I), and none in moderate (
K) and severe (
M) dry eye. Scale bars: (
A,
B) 10 μm; (
C–
M) 100 μm.