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Vet Microbiol. 1987 Aug;14(3):307-20.

Interaction of Rhodococcus equi with phagocytic cells from R. equi-exposed and non-exposed foals.

Author information

1
Department of Medicine, School of Veterinary Medicine, University of California, Davis 95616.

Abstract

The interaction of Rhodococcus equi with alveolar macrophages from adult horses, foals experimentally exposed to R. equi (sensitized foals) and non-exposed foals was studied using in vitro bactericidal assays, cytochemical staining and transmission electron microscopy. It was demonstrated that R. equi is a facultative intracellular parasite, able to survive and multiply within the alveolar macrophages of the host by interfering with phagosome-lysosome fusion. Opsonization of R. equi with antibody against capsular components was associated with increased phagosome-lysosome fusion and significantly enhanced (P less than 0.05) killing of the organism by alveolar macrophages from non-exposed foals. Macrophages from non-exposed foals were able to ingest the non-opsonized organism, but unable to kill greater than 65% of the infective dose by 6 h post-exposure. Alveolar macrophages from sensitized foals behaved as adult macrophages, able to kill greater than 95% of the infective dose by 6 h. Lymphocyte factors, derived by in vitro incubation of sensitized peripheral blood lymphocytes with R. equi surface antigens, enhanced macrophage bactericidal activity. Macrophages from non-exposed foals incubated in the presence of the lymphocyte factors had a 50% increase in killing of R. equi, while sensitized macrophages incubated with lymphocyte factors had a greater than 100% increase in killing capacity.

PMID:
3672873
DOI:
10.1016/0378-1135(87)90118-0
[Indexed for MEDLINE]

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