Guideline for the In Vivo Immunomodulatory Activity Test of Polysaccharide Based on Cyclophosphamide‐Induced Mouse Model

ABSTRACT The immune system serves as the primary defense mechanism against pathogens and plays a vital role in maintaining host homeostasis. In recent years, natural polysaccharides have emerged as promising immunomodulators due to their structural complexity and ability to regulate immune responses through multi‐target pathways. Unlike conventional synthetic drugs, these biomacromolecules offer low toxicity, superior biocompatibility, and bidirectional immunoregulation, making them attractive candidates for immune‐related therapies. However, establishing a robust and reproducible immunosuppressive animal model is essential for accurately evaluating their immunoregulatory efficacy. This study systematically investigates the critical parameters affecting immunosuppressive model establishment, including animal species, sex, immunosuppressant type and dosage, administration frequency, and model termination timing. By optimizing these factors, we propose a standardized in vivo evaluation system for assessing the immunoregulatory activity of polysaccharides. This framework provides a scientifically rigorous approach to studying natural immunomodulators, facilitating their development into effective therapeutic agents.