Characterization of peripheral blood and pulmonary leukocyte function in healthy foals.
Abstract: Studies in infants and foals indicate an age-dependent maturation of peripheral lymphocyte subsets. The age-dependent relationship for maturation of cellular immune responses, such as phagocytosis and lymphocyte responses of the peripheral and pulmonary-derived leukocytes, has not been characterized in foals. Lymphocyte subpopulations, mitogen stimulation response of lymphocytes, lymphokine-activated killing cell activity, phagocytosis and oxidative burst activity, and serum immunoglobulin (Ig) classes G and M concentrations were determined in developing foals. This study illustrates age-dependent changes in immunoglobulin class concentrations, lymphocyte subsets, and EqMHC Class II expression in cells of the peripheral blood and lungs of developing neonatal-to-weanling foals. The increase in peripheral blood and BAL B-lymphocytes and serum immunoglobulins in developing foals suggests expansion of immune cell populations during a time in which environmental pathogen exposure is great. General immune function, mitogenic responses, LAK cell activity, opsonized phagocytosis, and oxidative burst activity of newborns was similar to the adult horse. Total immune-cell numbers, rather than function, seemed to be the limiting factor in the development of the equine neonatal immune system. There was an age-related percent increase in the appearance of pulmonary lymphocytes, but a percent decrease in macrophages. Although development of the respiratory immune system follows changes in the peripheral blood, cellular expansion, activation, and migration may occur at a slower pace, making the respiratory environment susceptible to pathogens prior to optimal immune system maturity.
Publication Date: 2000-03-14 PubMed ID: 10713340DOI: 10.1016/s0165-2427(00)00149-5Google 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
This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.
This research focuses on understanding the development of immune functions, particularly leukocyte (white blood cell) behavior, in young foals. Age-dependent changes such as lymphocyte growth, mitogen stimulation response, immunoglobulin concentrations, and more were examined in newborn-to-weaning foals. Findings suggest that while newborn foals have similar immune function to adult horses, the total number of immune cells, not their function, may limit immune development.
Age-Dependent Maturation of Leukocytes
- This study investigated the development of immune responses in young foals, specifically looking at potential age-dependent maturation of lymphocyte subsets, immune cells important in fighting disease. The researchers detailed cellular immune responses including phagocytosis, a process by which cells engulf harmful foreign particles, and lymphocyte responses of peripheral and pulmonary-derived leukocytes, white blood cells derived from the blood or lungs.
Key Findings on Immune Cell Population Expansion
- The findings highlighted age-dependent changes in immunoglobulin class concentrations, lymphocyte subsets, and EqMHC Class II expression in cells of the peripheral blood and lungs in young foals. Immunoglobulins are types of proteins that function as antibodies, while EqMHC Class II refers to a set of cell surface proteins essential for the immune system to function properly.
- It was observed that there was an increase in certain white blood cells (peripheral blood and BAL B-lymphocytes) and serum immunoglobulins in foals as they develop, which, according to the authors, indicates an expansion of the immune cell populations during a time of high exposure to environmental pathogens.
Comparison with Adult Horses
- The study found that the immune function, mitogenic responses, opsonized phagocytosis, and oxidative burst activity of newborn foals were similar to those of the adult horse. Mitogenic responses refer to the response of lymphocytes to mitogens, substances that encourage cells to divide, while oxidative burst activity refers to a process where certain cells rapidly release reactive oxygen species to kill invading microbes.
Limitations in Immune System Development
- Despite the similarities with adult horses, the authors concluded that the total number of immune cells might be the limiting factor in the development of the equine neonatal immune system, rather than the function of these cells.
- The researchers also noted there was an age-related percentage increase in the number of pulmonary lymphocytes, but a percentage decrease in macrophages, which are a type of white blood cell crucial in killing pathogens.
Immune System Vulnerability to Pathogens
- The development of the respiratory immune system was seen to follow changes in the peripheral blood. Despite this, expansion, activation, and migration of immune cells may occur at a slower pace, making the respiratory environment susceptible to pathogens prior to optimal immune system maturity, according to the authors. This information suggests that younger foals could potentially be more susceptible to respiratory infections due to their immature immune system.
Cite This Article
APA
Flaminio MJ, Rush BR, Davis EG, Hennessy K, Shuman W, Wilkerson MJ.
(2000).
Characterization of peripheral blood and pulmonary leukocyte function in healthy foals.
Vet Immunol Immunopathol, 73(3-4), 267-285.
https://doi.org/10.1016/s0165-2427(00)00149-5 Publication
Researcher Affiliations
- The James A. Baker Institute for Animal Health, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853, USA. mbf6@cornelll.edu
MeSH Terms
- Aging / physiology
- Animals
- Animals, Newborn / physiology
- Bronchoalveolar Lavage Fluid / cytology
- Female
- Horses / immunology
- Immunoglobulin G / analysis
- Immunoglobulin M / analysis
- Immunophenotyping / veterinary
- Killer Cells, Lymphokine-Activated / physiology
- Leukocyte Count / veterinary
- Leukocytes / physiology
- Lung / immunology
- Lymphocyte Activation
- Lymphocyte Subsets / physiology
- Male
- Phagocytosis / physiology
- Respiratory Burst / physiology
Citations
This article has been cited 23 times.- Anna M, Łukasz M, Adam O, Chełmońska-Soyta A. Effectiveness of immunization with multi-component bacterial immunomodulator in foals at 35th day of life. Sci Rep 2022 Sep 22;12(1):15795.
- Rowland AL, Burns ME, Levine GJ, Watts AE. Preparation Technique Affects Recipient Immune Targeting of Autologous Mesenchymal Stem Cells. Front Vet Sci 2021;8:724041.
- Bordin AI, Cohen ND, Giguère S, Bray JM, Berghaus LJ, Scott B, Johnson R, Hook M. Host-directed therapy in foals can enhance functional innate immunity and reduce severity of Rhodococcus equi pneumonia. Sci Rep 2021 Jan 28;11(1):2483.
- Migdał A, Migdał Ł, Oczkowicz M, Okólski A, Chełmońska-Soyta A. Influence of Age and Immunostimulation on the Level of Toll-Like Receptor Gene (TLR3, 4, and 7) Expression in Foals. Animals (Basel) 2020 Oct 26;10(11).
- Rowland AL, Xu JJ, Joswig AJ, Gregory CA, Antczak DF, Cummings KJ, Watts AE. In vitro MSC function is related to clinical reaction in vivo. Stem Cell Res Ther 2018 Nov 8;9(1):295.
- Tallmadge RL, Wang M, Sun Q, Felippe MJB. Transcriptome analysis of immune genes in peripheral blood mononuclear cells of young foals and adult horses. PLoS One 2018;13(9):e0202646.
- Cywes-Bentley C, Rocha JN, Bordin AI, Vinacur M, Rehman S, Zaidi TS, Meyer M, Anthony S, Lambert M, Vlock DR, Giguère S, Cohen ND, Pier GB. Antibody to Poly-N-acetyl glucosamine provides protection against intracellular pathogens: Mechanism of action and validation in horse foals challenged with Rhodococcus equi. PLoS Pathog 2018 Jul;14(7):e1007160.
- Tallmadge RL, Žygelytė E, Van de Walle GR, Kristie TM, Felippe MJB. Effect of a Histone Demethylase Inhibitor on Equine Herpesvirus-1 Activity In Vitro. Front Vet Sci 2018;5:34.
- Tallmadge RL, Miller SC, Parry SA, Felippe MJB. Antigen-specific immunoglobulin variable region sequencing measures humoral immune response to vaccination in the equine neonate. PLoS One 2017;12(5):e0177831.
- Prieto JMB, Tallmadge RL, Felippe MJB. Developmental expression of B cell molecules in equine lymphoid tissues. Vet Immunol Immunopathol 2017 Jan;183:60-71.
- Cohen ND, Bourquin JR, Bordin AI, Kuskie KR, Brake CN, Weaver KB, Liu M, Felippe MJ, Kogut MH. Intramuscular administration of a synthetic CpG-oligodeoxynucleotide modulates functional responses of neutrophils of neonatal foals. PLoS One 2014;9(10):e109865.
- Battista JM, Tallmadge RL, Stokol T, Felippe MJ. Hematopoiesis in the equine fetal liver suggests immune preparedness. Immunogenetics 2014 Nov;66(11):635-49.
- Tallmadge RL, Stokol T, Gould-Earley MJ, Earley E, Secor EJ, Matychak MB, Felippe MJ. Fell Pony syndrome: characterization of developmental hematopoiesis failure and associated gene expression profiles. Clin Vaccine Immunol 2012 Jul;19(7):1054-64.
- Ryan C, Giguère S. Equine neonates have attenuated humoral and cell-mediated immune responses to a killed adjuvanted vaccine compared to adult horses. Clin Vaccine Immunol 2010 Dec;17(12):1896-902.
- Flaminio MJ, Tallmadge RL, Salles-Gomes CO, Matychak MB. Common variable immunodeficiency in horses is characterized by B cell depletion in primary and secondary lymphoid tissues. J Clin Immunol 2009 Jan;29(1):107-16.
- Jacks S, Giguère S, Crawford PC, Castleman WL. Experimental infection of neonatal foals with Rhodococcus equi triggers adult-like gamma interferon induction. Clin Vaccine Immunol 2007 Jun;14(6):669-77.
- Flaminio MJ, Borges AS, Nydam DV, Horohov DW, Hecker R, Matychak MB. The effect of CpG-ODN on antigen presenting cells of the foal. J Immune Based Ther Vaccines 2007 Jan 25;5:1.
- Flaminio MJ, Rush BR, Davis EG, Hennessy K, Shuman W, Wilkerson MJ. Simultaneous flow cytometric analysis of phagocytosis and oxidative burst activity in equine leukocytes. Vet Res Commun 2002 Feb;26(2):85-92.
- Berghaus LJ, Venner M, Helbig H, Hildebrandt D, Hart K. The potential value of cytokine, cortisol and vitamin D profiles in foals from birth to weaning for respiratory disease prediction on a farm endemic for Rhodococcus equi pneumonia. Equine Vet J 2026 Mar;58(2):359-371.
- da Silveira BP, Kahn SK, Legere RM, Bray JM, Cole-Pfeiffer HM, Golding MC, Cohen ND, Bordin AI. Enteral immunization with live bacteria reprograms innate immune cells and protects neonatal foals from pneumonia. Sci Rep 2025 May 25;15(1):18156.
- Julia M, Felippe B. Equine common variable immunodeficiency: lessons from 100 clinical cases. Equine Vet Educ 2024 Oct;36(10):543-554.
- 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.
- Hostetter SJ, Clark SK, Gilbertie JM, Wiechert SA, Jones DE, Sponseller BA. Age-related variation in the cellular composition of equine bronchoalveolar lavage fluid. Vet Clin Pathol 2017 Jun;46(2):344-353.
Use Nutrition Calculator
Check if your horse's diet meets their nutrition requirements with our easy-to-use tool Check your horse's diet with our easy-to-use tool
Talk to a Nutritionist
Discuss your horse's feeding plan with our experts over a free phone consultation Discuss your horse's diet over a phone consultation
Submit Diet Evaluation
Get a customized feeding plan for your horse formulated by our equine nutritionists Get a custom feeding plan formulated by our nutritionists
