Functional characterization of equine neutrophils in response to calcium ionophore A23187 and phorbol myristate acetate ex vivo.
Abstract: Equine neutrophils (PMN) play a critical role in inflammatory processes in horses. The objective of this study was to characterize equine PMN function ex vivo following stimulation with calcium ionophore A23187 (A23187) and phorbol myristate acetate (PMA). These stimulants trigger different branches of the PMN activation process that occurs in vivo. Equine PMN were isolated from the whole blood of six clinically normal geldings using a one-step discontinuous Percoll gradient technique. Neutrophil aggregation, degranulation, and superoxide anion production were evaluated in assay systems which had previously been established to quantitate PMN function. Dose-response curves for A23187 and PMA were derived for the three functions. Results indicate that equine PMN aggregation and superoxide anion production are more responsive to activation by PMA as the maximum change in percent transmittance and maximum nanomoles of superoxide anion produced following PMA stimulation (60.8% and 10.4 nmol per 10(6) cells, respectively) were greater than those values stimulated by A23187 (41.5% and 5.2 nmol per 10(6) cells, respectively). However, degranulation was found to be more responsive to A23187 stimulation (maximum percent degranulation: 56.1%) than to PMA stimulation (maximum percent degranulation: 30.7%). Dose-response curves following A23187 and PMA stimulation revealed that superoxide anion production had the lowest threshold concentration among the three functions. Degranulation had the highest threshold concentration among the three functions for both stimulants. Results indicate that equine PMN functions differ in their dependence on second messengers in the activation pathway. These functions also occur in a dose-dependent manner and differ in the threshold concentrations required for their stimulation.
Publication Date: 1997-05-01 PubMed ID: 9223228DOI: 10.1016/s0165-2427(96)05750-9Google Scholar: Lookup
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- Comparative Study
- Journal Article
Summary
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The research article investigates how equine neutrophils, a type of white blood cell in horses, respond to two stimulants, calcium ionophore A23187 and phorbol myristate acetate. It discovers that the response changes depending on the stimulant used, the function of the neutrophils, and the dosage of the stimulant.
The Experiment Procedure
- The study observes equine neutrophils, which play a significant role in inflammation in horses. Neutrophils were obtained from the blood of healthy geldings.
- The aim was to understand their function following stimulation with calcium ionophore A23187 (A23187) and phorbol myristate acetate (PMA). These stimulants activate different parts of the in vivo (inside the body) neutrophil activation process.
- The team examined neutrophil aggregation (cluster formation), degranulation (release of granules), and superoxide anion generation (O2- creation, indicating a type of inflammation).
Findings From the Responses to A23187 and PMA
- Different dose-response curves for A23187 and PMA were found for the three neutrophil functions.
- Equine neutrophil aggregation and superoxide anion production demonstrated a greater response to PMA. Namely, PMA yielded a change in transmittance of 60.8%, the measure of cell aggregation, and 10.4 nanomoles of superoxide anion per million cells. This was more than A23187’s results, which were 41.5% and 5.2 nanomoles, respectively.
- However, A23187 caused more degranulation with a maximum of 56.1% compared to PMA’s 30.7%.
Implications of the Dose-Response Curves
- The dose-response curves showed that superoxide anion production had the lowest need for stimulant concentration, known as a threshold among the three functions.
- In contrast, degranulation required the highest stimulant concentration among both stimulant types.
- This suggests that neutrophil functions vary in their dependency on second messengers in the activation pathway, entities that transfer the chemical signal inside a cell on cell receptor activation.
- These functions also happen in a dose-dependent manner and vary in the stimulant concentrations required for their activation.
Cite This Article
APA
Moore T, Wilcke J, Chilcoat C, Eyre P, Crisman M.
(1997).
Functional characterization of equine neutrophils in response to calcium ionophore A23187 and phorbol myristate acetate ex vivo.
Vet Immunol Immunopathol, 56(3-4), 233-246.
https://doi.org/10.1016/s0165-2427(96)05750-9 Publication
Researcher Affiliations
- Virginia-Maryland Regional College of Veterinary Medicine, Virginia Polytechnic Institute and State University, Blacksburg 24060, USA.
MeSH Terms
- Animals
- Calcimycin / pharmacology
- Cell Aggregation / drug effects
- Cell Degranulation / drug effects
- Enzyme Activation / drug effects
- Horses / blood
- Horses / immunology
- In Vitro Techniques
- Ionophores / pharmacology
- Male
- Neutrophils / drug effects
- Neutrophils / immunology
- Neutrophils / physiology
- Protein Kinase C / metabolism
- Superoxides / metabolism
- Tetradecanoylphorbol Acetate / pharmacology
Citations
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