In situ hybridization analysis of ICAM-1 (CD54) mRNA on conjunctival epithelium during allergic inflammation.
BACKGROUND
The intercellular adhesion molecule ICAM-1 has been detected by immunohistochemical methods on epithelial cells of the conjunctiva and nose during allergic inflammation.


OBJECTIVE
The aim of the present study was to evaluate whether ICAM-1 expression on conjunctival epithelium derives from endogenous synthesis or is merely due to passive uptake of soluble ICAM-1 released from inflammatory cells.


METHODS
In situ hybridization was performed using a 3' end dygoxygenin-labelled specific DNA oligonucleotide probe on fixed conjunctival smears from allergic subjects challenged with, or naturally exposed to the allergen, and from healthy subjects. Immunocytochemistry for ICAM-1 was performed by alkaline phosphatase antialkaline phosphatase.


RESULTS
In allergic patients, both naturally exposed to the allergen and after specific challenge, a clear hybridization pattern on epithelial cells was apparent. Out of allergen exposure, some symptomfree pollinosic subjects, as well as a few healthy volunteers showed mild ICAM-1 mRNA cytoplasmic staining in the absence of immunohistochemically detectable ICAM-1. This finding may explain the very early appearance of ICAM-1 on conjunctival epithelium following specific challenge in allergic individuals.


CONCLUSIONS
These results indicate that the presence of ICAM-1 on conjunctival epithelium during allergic inflammation derives from endogenous synthesis and not from uptake of soluble ICAM-1.
Bagnasco
M
M
Allergy and Clinical Immunology Service, Department of Internal Medicine, University of Genoa, Italy.
Pesce
G
G
Fiorino
N
N
Riccio
A M
AM
Ciprandi
G
G
Buscaglia
S
S
Canonica
G W
GW
D016475:3T3 Cells; D000328:Adult; D000818:Animals; D002460:Cell Line; D003228:Conjunctiva / Q000276:immunology*; D003233:Conjunctivitis, Allergic / Q000276:immunology*; D004848:Epithelium / Q000276:immunology; D005260:Female; D006801:Humans; D017403:In Situ Hybridization; D018799:Intercellular Adhesion Molecule-1 / Q000096:biosynthesis*; D008297:Male; D051379:Mice; D008875:Middle Aged; D009296:Nasal Cavity / Q000276:immunology; D012333:RNA, Messenger / Q000032:analysis
D012333:RNA, Messenger; D018799:Intercellular Adhesion Molecule-1