IL-32, a newly-discovered proinflammatory cytokine that activates the p38MAPK and NF-kappaB pathways, is an important player in innate and adaptive immune response. IL-32, a cytokine produced mainly by T, natural killer, and epithelial cells induces significant amounts of TNFalpha and MIP-2 and increases the production of both cytokines in a dose-dependent manner. IL-32 has been implicated in inflammatory disorders, mycobacterium tuberculosis infections, inflammatory bowel disease, and influenza A virus infection, as well as in some autoimmune diseases, such as rheumatoid arthritis, ulcerative colitis and Crohn?s disease and in human stomach cancer, human lung cancer and breast cancer tissues. Moreover, it has been reported that IL-32 has pro-inflammatory effects on myeloid cells and causes the differentiation of osteoclast precursors into multinucleated cells expressing specific osteoclast markers. We recently found that human IL-32 has the capacity to provoke histamine release in human-derived cord blood mast cells (HDCBMC), but not in LAD 2 cells nor in rat peritoneal mast cells (RPMC), showing that IL-32 may be specie specific and act more in mature human mast cells (HDCBMC) than in transformed mast cells (LAD 2 cells). Certainly, IL-32 is another potent proinflammatory cytokine, however, the specific role of this newly-discovered protein in the network of cytokine biology remains to be determined.