{Reference Type}: Journal Article {Title}: The complex role of IL-10 in malignant ascites: a review. {Author}: Huang Y;Zou K;Jiang H;Li Z; {Journal}: Cancer Immunol Immunother {Volume}: 73 {Issue}: 2 {Year}: 2024 Jan 27 {Factor}: 6.63 {DOI}: 10.1007/s00262-023-03616-y {Abstract}: The emergence of malignant ascites (MA) indicates poor prognoses in patients with ovarian, gastrointestinal, breast, and pancreatic cancer. Interleukin-10 (IL-10) is a pleiotropic cytokine with immunoregulatory effects in tumor microenvironment. The level of IL-10 in MA varied across cancer types and patients, influencing cancer progression and outcomes. Originating from various immune and cancer cells, IL-10 contributes to complex signaling pathways in MA. Systemic IL-10 administration, although the evidence of its efficacy on MA is limited, still emerges as a promising therapeutic strategy because it can increase CD8+ T cells cytotoxicity and invigorate exhausted CD8+ tumor infiltration lymphocytes (TILs) directly. IL-10 signaling blockade also demonstrates great potential when combined with other immunotherapies in MA treatment. We reviewed the levels, origins, and functions of IL-10 in malignant ascites and overviewed the current IL-10 signaling targeting therapies, aiming to provide insights for MA treatment.