RESUMO
A model of topically induced conjunctival anaphylaxis has been developed. Male Sprague-Dawley rats were immunized by infection with 3000 Nippostrongylus brasiliensis larvae and challenged topically on the eye 4 weeks later. Application of worm antigen alone did not induce clinical (conjunctival edema) or histologic (mast-cell degranulation) signs of anaphylaxis. Topical challenge with antigen 15 min after topical application of dithiothreitol (DTT), a mucolytic agent, elicited conjunctival edema and mast-cell degranulation within the first hour after challenge. At 6 and 24 hr, no clinical change was evident and conjunctival mast cells had again become granulated. At none of the three intervals (1, 6 and 24 hr) was there a significant increase in neutrophils, lymphocytes, eosinophils or macrophages in tissues from DTT-pretreated, antigen-eyes. The present model of ocular anaphylaxis resembles the ocular component of human hay fever in that sensitization prior to challenge is essential, the antigen is presented topically to the ocular tissues, conjunctival edema is the clinical manifestation and mast cell degranulation characterizes the histologic changes.
Assuntos
Anafilaxia/imunologia , Antígenos de Helmintos/imunologia , Infecções por Nematoides/imunologia , Animais , Túnica Conjuntiva/imunologia , Doenças da Túnica Conjuntiva/etiologia , Ditiotreitol/farmacologia , Relação Dose-Resposta Imunológica , Edema/etiologia , Contagem de Leucócitos , Masculino , Nippostrongylus , Ratos , Ratos Endogâmicos , Fatores de TempoRESUMO
In orbital exenteration specimens from 14 rats, 93% of the mast cells were found in the lids, the limbus, and the conjunctiva, 5% in the orbital tissues, and less than 1% in the globe. The density of mast cells was highest in lid (2843/mm3), limbus (2822/mm3), and orbit (2184/mm3) and lowest in bulbar conjunctiva (794/mm3), ciliary body (512/mm3), and sclera (176/mm3). There was no significant difference in the distribution or density of mast cells in orbital exenteration specimens from normal rats compared with rats infected with the worm Nippostrongylus brasiliensis. We concluded that certain ocular structures are rich in mast cells, which suggests that these structures might be susceptible to injury mediated by mast cell products.