Variability in peripheral blood enrichment techniques can alter equine leukocyte cellularity, viability and function

Area of Science:

• Comparative immunology
• Equine veterinary science
• Cellular biology

Background:

• Peripheral blood analysis is crucial for assessing animal health.
• Leukocyte enrichment techniques vary, potentially impacting experimental outcomes.
• Standardized methods are needed for reliable equine immune cell analysis.

Purpose of the Study:

• To compare the efficacy of two equine peripheral blood leukocyte enrichment techniques.
• To evaluate the impact of Histopaque (His) versus syringe-lymphocyte separation medium (Syr-LSM) on immune cell characteristics and function.
• To determine how enrichment method affects key immunological assay endpoints.

Main Methods:

• Peripheral blood from 12 healthy horses was processed using two enrichment methods: Histopaque gradient (His) and modified syringe-lymphocyte separation medium (Syr-LSM).
• Evaluated endpoints included cell recovery, viability, purity, cell marker phenotype (CD8+, CD21+), spontaneous and mitogen-induced proliferation, and TNFα secretion.
• Specific assays involved flow cytometry for cell phenotyping and cell culture for proliferation and cytokine analysis.

Main Results:

• The Syr-LSM technique yielded significantly higher leukocyte recovery per mL of blood and improved cell viability compared to His.
• The His technique resulted in a significant increase in CD8+ and CD21+ T-cell subsets and Concanavalin A (Con A)-induced proliferation.
• Leukocyte purity and TNFα concentrations after 72-hour culture were comparable between the His and Syr-LSM methods.

Conclusions:

• The choice of peripheral blood leukocyte enrichment technique significantly influences immunological assay results in horses.
• Syr-LSM enhances cell yield and viability, while His enriches specific T-cell populations.
• Methodological differences in leukocyte enrichment can alter data interpretation in equine immunology studies.