Effects of pentoxifylline on immediate and late-phase cutaneous reactions in response to anti-immunoglobulin E antibodies in clinically normal dogs.
OBJECTIVE
To characterize the effects of pentoxifylline on the gross and microscopic variables associated with immediate and late-phase inflammation following injection of IgE-specific antibodies in the skin of clinically normal dogs.


METHODS
6 healthy adult mixed-breed dogs.


METHODS
Intradermal injections (0.1 mL each) of PBS solution, histamine phosphate, and cross-linking rabbit-origin anti-canine IgE antibodies (3 injections/dog) were administered at 0 hours on day 0; wheal sizes were evaluated at 20 minutes, 6 hours, and 24 hours. Biopsy specimens of injected and noninjected skin were collected 24 hours after injection. On day 2, treatment with pentoxifylline (20 mg/kg, PO, q 8 h) was initiated and continued until day 30. For each dog, injection, measurement, and biopsy procedures were repeated on days 30 to 31 and on days 37 to 38 (ie, after discontinuation of pentoxifylline administration).


RESULTS
Pentoxifylline administration was associated with a significant decrease in wheal size at 6 and 24 hours (but not at 20 minutes) after injection of anti-canine IgE. Repeated injections performed 1 week after drug discontinuation revealed partial recovery of the 6-hour cutaneous reaction and complete recovery of the 24-hour cutaneous reaction. Pentoxifylline administration was also associated with inhibition of mast cell degranulation and significant decreases in the total numbers of cutaneous inflammatory cells and eosinophils, compared with pretreatment findings.


CONCLUSIONS
In clinically normal dogs, pentoxifylline effectively impaired late-phase reactions but not immediate reactions at sites of intradermal injection of IgE-specific antibodies by inhibiting mast cell degranulation and recruitment of cutaneous inflammatory cells, especially eosinophils.
Department of Veterinary Clinical Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge, LA 70803.
Cherie M
CM
Pucheu-Haston
Kaitlin A
KA
Kasparek
Rhett W
RW
Stout
Michael T
MT
Kearney
Bruce
B
Hammerberg
D000279:Administration, Cutaneous; D000818:Animals; D000888:Antibodies, Anti-Idiotypic / Q000009:adverse effects*; D004283:Dog Diseases / Q000139:chemically induced / Q000188:drug therapy*; D004285:Dogs; D016166:Free Radical Scavengers / Q000627:therapeutic use*; D007073:Immunoglobulin E / Q000276:immunology; D007249:Inflammation / Q000188:drug therapy / Q000662:veterinary; D007271:Injections, Intradermal / Q000662:veterinary; D007428:Intradermal Tests / Q000662:veterinary; D010431:Pentoxifylline / Q000627:therapeutic use*; D012871:Skin Diseases / Q000139:chemically induced / Q000188:drug therapy / Q000662:veterinary*; D012882:Skin Tests / Q000662:veterinary
D000888:Antibodies, Anti-Idiotypic; D016166:Free Radical Scavengers; C026408:anti-IgE antibodies; D007073:Immunoglobulin E; D010431:Pentoxifylline