Evaluation of alveolar macrophage function after experimental infection with equine herpesvirus-1 in horses

The role of the pulmonary alveolar macrophages (PAM) in the lung defense mechanism was evaluated in horses infected with equine hespesvirus-1 (EHV-1). Five adult horses were exposed to 10(6.6) TCID50 EHV-1 by intranasal instillation. Cytology of bronchoalveolar lavage (BAL) was performed using cytocentrifugation of samples and slides stained by Rosenfeld. Cell concentration was adjusted to 2´10(6) cells/ml, for the measurement of macrophage activity - spreading, phagocytosis of zymosan particles and release of hydrogen peroxide (H2O2). All animals were positive in virus isolation on the second, third and fifth days post-inoculation (DPI). Seroconversion was observed on the 14th DPI. Lymphocytosis was observed by BAL cytology on the 16th DPI. Measurement of macrophage activity demonstrated a marked increase in the spreading rate, on the 23rd and 30th DPI. Phagocytosis was decreased on the second DPI, and returned to levels similar to those observed before inoculation on the 23rd DPI. The amount of H2O2 released by PAM declined on day 2, but, by day 16, they returned to values similar to those observed before inoculation. The decline in PAM activity in the acute phase of disease is indirect evidence that these cells have an important role in lung defense mechanisms against this agent.

Avaliaçäo da funçäo de macrófagos alveolares em cavalos clinicamente sadios / Evaluation of alveolar macrophage function in healthy horses

Devido à importância dos macrófagos alveolares (MA) nos mecanismos de defesa pulmonar, foram realizados estudos para avaliar a atividade desses fagócitos em cavalos hígidos. Foram realizados lavados broncoalveolares (LBA) em cinco cavalos clinicamente sadios. A citologia foi realizada pela citocentrifugaçäo das ammostras e posterior confecçäo de lâminas coradas pelo método de Rosenfeld. Todas as amostras do LBA foram centrifugadas e a concentraçäo celular foi ajustada para 2x10 elevada a sexta potência células/ml, para a mensuraçäo da atividade macrofágica (testes de espraiamento, fagocitose e liberaçäo de peróxido de hidrogênio). A contagem diferencial das células presentes no LBA demonstrou a predominância de macrófagos (59,0ñ6,9 por cento). Os resultados obtidos nos testes de mensuraçäo da atividade macrofágica foram: índice de espraiamento 25,1ñ19,7 por cento, índice de fagocitose 89,4ñ6,2 por cento e liberaçäo de peróxido de hidrogênio 1,6ñ0,3nmoles/2x10 elevado a quinta potência células (sem PMA - phorbol 12-myristate 13-acetate) e 1,8ñ0,4nmoles/2x10 elevado a quinta potência células (com PMA). Os resultados demonstraram um padräo de atividade para MA de cavalos hígidos, os quais apresentaram índices de ativaçäo mesmo sem elicitaçäo prévia, indicando que as técnicas utilizadas foram adequadas para tal propósito