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Neutrophil phagocytic and serum opsonic response of the foal to Corynebacterium equi.
Abstract: This study was undertaken to examine the neutrophil response to Corynebacterium (Rhodococcus) equi, and to assess the possibility of neutrophil immaturity or malfunction in predisposition to C. equi pneumonia in foals. Neutrophil phagocytosis of Corynebacterium (Rhodococcus) equi was studied in foals from birth to 6 months of age. Chemiluminescence (CL) and bactericidal assays were used to assay the phagocytic response of peripheral blood neutrophils to C. equi in vitro. Results of in vitro bactericidal and CL assays indicate that foal neutrophils are able to ingest and kill C. equi, however are significantly more efficient in the presence of opsonization with specific antibody, and less importantly complement. Neutrophil CL was significantly decreased (p greater than .05) or eliminated by antibody adsorption, heat-inactivation, or removal of serum from the assay. The ability of the neutrophil to kill C. equi, as measured by in vitro bactericidal assay, was greater than 90% killing by 6 hours, in the presence of C. equi antiserum. Bactericidal activity was reduced to less than 40% killing when C. equi adsorbed serum was used as the opsonin source. As CL results indicated complement involvement in the opsonization of C. equi, the temporal development of hemolytic and conglutinating complement was measured in normal and C. equi infected foals. Neither defects nor age-related suppression of neutrophil function or complement activity were detected in C. equi affected foals, suggesting that these are not pathogenic mechanisms involved in foal pneumonia.
Publication Date: 1987-03-01 PubMed ID: 3109114DOI: 10.1016/0165-2427(87)90096-1Google Scholar: Lookup The Equine Research Bank provides access to a large database of publicly available scientific literature. Inclusion in the Research Bank does not imply endorsement of study methods or findings by Mad Barn.
- Journal Article
- Research Support
- Non-U.S. Gov't
Summary
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The research article looks into the response of neutrophils, a type of immune cell, to the bacterium Corynebacterium equi, in foals. The study explores whether there is a link between immature or improperly functioning neutrophils and foals’ susceptibility to pneumonia caused by C. equi.
Study Procedure
- The study observed the neutrophil response to Corynebacterium equi in young horses from birth to six months old.
- Two tests, namely chemiluminescence (CL) and bactericidal assay, were used to measure the reaction of neutrophils in the blood.
- The tests were conducted in vitro, or outside of a living organism, using conditions that mimic the internal environment of the body.
Findings
- The study concluded that foal neutrophils can consume and kill C. equi, which is more effective when opsonization occurs with a specific antibody and less importantly, complement, a part of the immune system.
- Opsonization is the process where pathogens are marked for phagocytosis (consumption) by immune cells.
- When certain conditions (like heat-inactivation, absence of serum, antibody adsorption) were introduced, the neutrophil response significantly reduced or disappeared.
- When C. equi antiserum was present, the neutrophil’s ability to kill C. equi was above 90% in six hours. But, this percentage dropped below 40% when C. equi adsorbed serum served as the opsonin source.
Significance and Conclusion
- The results suggested that complement plays a role in the opsonization of C. equi, leading the researchers to measure complement development over time in both infected and healthy foals.
- The researchers did not observe any defects or age-associated suppression of neutrophil function or complement activity in foals affected by C. equi – meaning these aren’t factors contributing to pneumonia in foals.
- These findings dispel any previous assumptions that neutrophil immaturity or malfunction might predispose foals to pneumonia caused by C. equi.
Cite This Article
APA
Hietala SK, Ardans AA.
(1987).
Neutrophil phagocytic and serum opsonic response of the foal to Corynebacterium equi.
Vet Immunol Immunopathol, 14(3), 279-294.
https://doi.org/10.1016/0165-2427(87)90096-1 Publication
Researcher Affiliations
MeSH Terms
- Animals
- Antibodies, Bacterial / immunology
- Blood Bactericidal Activity
- Complement System Proteins / physiology
- Horses / immunology
- Listeria monocytogenes / immunology
- Luminescent Measurements
- Neutrophils / immunology
- Opsonin Proteins
- Phagocytosis
- Rhodococcus / immunology
- Rhodococcus / pathogenicity
- Staphylococcus aureus / immunology
Citations
This article has been cited 8 times.- Cohen ND, Kahn SK, Cywes-Bentley C, Ramirez-Cortez S, Schuckert AE, Vinacur M, Bordin AI, Pier GB. Serum Antibody Activity against Poly-N-Acetyl Glucosamine (PNAG), but Not PNAG Vaccination Status, Is Associated with Protecting Newborn Foals against Intrabronchial Infection with Rhodococcus equi. Microbiol Spectr 2021 Sep 3;9(1):e0063821.
- Harvey AB, Bordin AI, Rocha JN, Bray JM, Cohen ND. Opsonization but not pretreatment of equine macrophages with hyperimmune plasma nonspecifically enhances phagocytosis and intracellular killing of Rhodococcus equi. J Vet Intern Med 2021 Jan;35(1):590-596.
- Flaminio MJ, Nydam DV, Marquis H, Matychak MB, Giguère S. Foal monocyte-derived dendritic cells become activated upon Rhodococcus equi infection. Clin Vaccine Immunol 2009 Feb;16(2):176-83.
- Roncada P, Bonizzi L, Fortin R, Menandro ML, Greppi GF. A proteomic approach to investigate immunity against R. Equi in foals. Vet Res Commun 2005 Aug;29 Suppl 2:215-9.
- Martens RJ, Cohen ND, Jones SL, Moore TA, Edwards JF. Protective role of neutrophils in mice experimentally infected with Rhodococcus equi. Infect Immun 2005 Oct;73(10):7040-2.
- Prescott JF. Rhodococcus equi: an animal and human pathogen. Clin Microbiol Rev 1991 Jan;4(1):20-34.
- Villalba-Orero M, Gómez CA, Valero-Gónzalez M, Venegas N, Criado G, Martín-Cuervo M. Blood parameters in neonatal foal and colostrum quality as possible early markers for increased risk of developing Rhodococcus equi pneumonia. Front Vet Sci 2025;12:1654052.
- da Silveira BP, Cohen ND, Lawhon SD, Watson RO, Bordin AI. Protective immune response against Rhodococcus equi: An innate immunity-focused review. Equine Vet J 2025 May;57(3):563-586.
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