Dendrobium officinale leaf polysaccharide has a dual effect of alleviating the syndromes of immunosuppressed mice and modulating immune system of normal mice

[Display omitted] •DOLP reversed thymus and spleen damage in immunosuppressed mice.•DOLP backregulated PLT, TNF-α, INF-γ, IL-6, IgG and IgM in immunosuppressed mice.•DOLP increased levels of TNF-α, INF-γ, and IL-6 in normal mice.•DOLP improved the structure of gut microbiota in immunosuppressed and normal mice.•DOLP could exert immune modulating effects on immunosuppressed mice and normal mice. This study aimed to explore the immunomodulatory activity of Dendrobium officinale leaf polysaccharide (DOLP) in both immunosuppressed and normal mice. The data showed that DOLP significantly reversed thymic and splenic damage in immunosuppressed mice, regulated their peripheral blood cells (PLT, etc.), immune-related cytokines (TNF-α, INF-γ and IL-6) and immunoglobulins (IgA, IgG and IgM) production, and increased the relative abundance of beneficial bacteria (Lactobacillus and Bifidobacterium, etc.) while decreased that of pathogenic bacteria (Desulfovibrio, etc.). In normal mice, DOLP significantly increased immune-related cytokines (TNF-α, INF-γ, and IL-6), gut microbiota diversity, and the relative abundance of beneficial bacteria (unclassified_f_Lachnospiraceae_NK4A136_group, etc.). The results indicated that DOLP could exert immune modulating effects both on immunosuppressed mice and normal mice by modulating immune parameters and gut microbiota. These findings provide new insights into the immune-modulating effects of DOLP and a solid basis for the thorough utilization of DOLP.