Neutrophil infiltration is implicated in the sustained thermal hyperalgesic response evoked by allergen provocation in actively sensitized rats.
It has been proposed that allergen provocation induces hyperalgesia but the involvement of immunoglobulin E and leukocytes remains poorly understood. Here, we have compared the profile of allergen-evoked thermal hyperalgesic response in both passively and actively sensitized rats, and investigated the role of leukocytes in allergen-evoked nociception. Wistar rats were passively sensitized with an intraplantar injection of immunoglobulin E anti-dinitrophenylated bovine serum albumin monoclonal antibody (0.5 microg/paw), and challenged with dinitrophenylated bovine serum albumin (0.5 microg/paw) 24 h later. Alternatively, the animals were actively sensitized with a mixture of Al(OH)3 and ovalbumin and challenged intraplantarly with ovalbumin (12 microg/paw) 14 days later. We found that the thermal hyperalgesic responses set in very rapidly and with comparable intensity in both passively and actively sensitized rats. However, while in the former group the response was shorter, peaking within 1 h and reducing thereafter, a marked plateau was observed from 1 to 6 h post-challenge in the latter group. Actively sensitized rats also had higher neutrophil influx in the plantar tissue, as attested by both myeloperoxidase activity and histological analysis. Treatment of actively sensitized rats with either fucoidin (10 mg/kg, i.v) or anti-rat neutrophil antiserum (i.p.) reduced neutrophil accumulation and the late hyperalgesic response noted from 3 to 6 h post-challenge. Thus, we conclude that though immunoglobulin E-mediated mechanisms can cause thermal hyperalgesia, components of the cellular immune reaction are crucial in order to amplify and sustain the immediate hyperalgesic response triggered by allergen, in a process dependent on neutrophil recruitment.
Lavich
Tatiana Ramos
TR
Departamento de Fisiologia e Farmacodinâmica, Instituto Oswaldo Cruz-Fiocruz, Rio de Janeiro, Brazil.
Siqueira
Rodrigo de Azeredo
Rde A
Farias-Filho
Francisco Alves
FA
Cordeiro
Renato Sérgio Balão
RS
Rodrigues e Silva
Patrícia Machado
PM
Martins
Marco Aurélio
MA
D000485:Allergens / Q000008:administration & dosage / Q000276:immunology*; D000818:Animals; D006930:Hyperalgesia / Q000139:chemically induced* / Q000276:immunology* / Q000473:pathology; D007073:Immunoglobulin E / Q000276:immunology*; D008297:Male; D020556:Neutrophil Infiltration / Q000187:drug effects* / Q000276:immunology*; D051381:Rats; D017208:Rats, Wistar
D000485:Allergens; D007073:Immunoglobulin E