Activity of feline interferon-omega after ocular or oral administration in cats as indicated by Mx protein expression in conjunctival and white blood cells.
OBJECTIVE
To assess the biological response to recombinant feline interferon-omega (rFeIFN-omega) following ocular or oral administration in cats via estimation of Mx protein expression in conjunctival cells (CCs) and WBCs.


METHODS
10 specific pathogen-free cats.


METHODS
In multiple single-dose drug experiments, each cat received various concentrations of rFeIFN-omega administered topically into both eyes (50 to 10,000 U/eye) and orally (200 to 20,000 units). The same cats received saline (0.9% NaCl) solution topically and orally as control treatments. The CCs and WBCs were collected prior to treatment (day 0), on day 1, and every third or seventh day thereafter until samples yielded negative results for Mx protein. Samples were examined for Mx protein expression via immunohistochemistry and immunoblotting procedures involving murine anti-Mx protein monoclonal antibody M143.


RESULTS
After topical application of 10,000 U of rFeIFN-omega/eye, CCs stained for Mx protein for a minimum of 7 days, whereas WBCs were positive for Mx protein for a minimum of 31 days. After topical application of lower concentrations, CCs did not express Mx protein, in contrast to WBCs, which stained for Mx protein at 1,000 units for at least 1 day. Following oral administration, Mx protein was expressed in WBCs at rFeIFN-omega concentrations as low as 200 units, whereas CCs did not stain for Mx protein at any concentration.


CONCLUSIONS
Results indicate that Mx protein expression (a marker of the biological response to rFeIFN-omega) in CCs and WBCs of rFeIFN-omega-treated cats depends on the dose of rFeIFN-omega, site of administration, and cell type.
Bracklein
Thorsten
T
Ophthalmology Unit, Department of Small Animals, Vetsuisse Faculty, University of Zurich, Winterthurerstrasse 260, 8057 Zurich, Switzerland.
Theise
Sandra
S
Metzler
Alfred
A
Spiess
Bernhard M
BM
Richter
Marianne
M
D000284:Administration, Oral; D000287:Administration, Topical; D000818:Animals; D000998:Antiviral Agents / Q000008:administration & dosage / Q000494:pharmacology; D002415:Cats / Q000097:blood / Q000378:metabolism*; D003228:Conjunctiva / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D005260:Female; D019204:GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D005786:Gene Expression Regulation / Q000187:drug effects*; D007370:Interferon Type I / Q000008:administration & dosage* / Q000494:pharmacology*; D007962:Leukocytes / Q000187:drug effects* / Q000378:metabolism; D008297:Male; D064547:Myxovirus Resistance Proteins
D000998:Antiviral Agents; D007370:Interferon Type I; D064547:Myxovirus Resistance Proteins; C063743:interferon omega 1; D019204:GTP-Binding Proteins