RESIDENCE AND RECRUITMENT OF LEUKOCYTES TO THE EQUINE LUNG AFTER EHV-1 INFECTION

This study characterised bronchoalveolar leucocytes collected by lavag e from five susceptible and two immune ponies before and after nebulis ed aerosol infection with equid herpesvirus-1 (EHV-1). Leucocyte count s and lymphocyte phenotypic analyses were performed using either diffe rential staining or an indirect immunofluorescence assay with monoclon al antibodies specific for equine (Eq) CD4, CD5, CD8 and B lymphocytes . After EHV-1 infection, significant changes developed: a transient ne utrophilia occurred on Day 2, coincident with a reduction in macrophag e numbers and an EqCD5(+), EqCD4(+) and EqCD8(+) lymphopaenia. On Day 21, a significant rise in EqCD8(+) lymphocytes with an associated fall in the EqCD4(+):EqCD8(+) ratio and fluctuations in B lymphocyte pheno types were observed, This study shows that following EHV-1 infection, the bronchoalveolar compartment is subject to dynamic leucocyte migrat ion which may have an important role in immunopathogenesis and recover y from disease.