Cynomolgus Monkey (Macaca fascicularis) Interleukin-1 Alpha (IL-1α) is a pro-inflammatory cytokine belonging to the IL-1 family—which includes IL-1α, IL-1β, and the IL-1 receptor antagonist (IL-1Ra)—and plays a key role in initiating innate and sterile inflammatory responses. IL-1α is constitutively expressed in epithelial and endothelial tissues and functions as an intracellular alarmin that is rapidly released upon cell injury, necrosis, or viral infection. Upon binding to the IL-1 receptor type 1 (IL-1R1), cynomolgus IL-1α activates NF-κB and MAPK signaling pathways that drive leukocyte recruitment, endothelial activation, fever, and amplification of downstream pro-inflammatory cytokine cascades. Highly homologous to human IL-1α, it is critically involved in nonhuman primate models of infectious diseases such as dengue, influenza, SARS-CoV-2, tuberculosis, and bacterial sepsis, where early IL-1α release contributes to systemic inflammation and disease severity. IL-1α is also relevant in studies of autoimmune disease, tissue injury, and cytokine release syndromes evaluated during biologic safety testing. Because cynomolgus monkeys are widely used in preclinical research due to their close genetic and immunologic similarity to humans, characterization of IL-1α supports investigations into inflammasome-independent inflammation, host–pathogen interactions, and therapeutic modulation of IL-1 signaling, providing critical translational insight into human inflammatory and infectious diseases.