Key Takeaways

• IL-15 is a proinflammatory cytokine that is essential for the development, survival, and activation of NK cells and CD8+ T cells, which are important in the immune response to pathogens and cancer.
• Dysregulated or chronically high IL-15 signaling contributes to several autoimmune diseases, osteoarthritis pain, and certain blood cancers, making “too much IL-15” a problem in some contexts.​ Low IL-15 may contribute to a blunted immune response to cancer or persistent infections.
• Genetic variants in IL15 and IL15RA influence muscle strength gains from exercise as well as risks for celiac disease, leukemia, and osteoarthritis.​
• Lifestyle and supplement factors—including sleep/circadian alignment, exercise, vitamin D, zinc, probiotics, beta-alanine, butyrate, and colostrum—can modulate IL-15 signaling up or down, which may be helpful depending on whether infection, autoimmunity, or cancer is the primary concern.​