IL16 is a CD8+ T cell-derived cytokine that induces chemotaxis of CD4+ T cells and CD4+ monocytes and eosinophils. Analysis by gel filtration suggests that, under physiological conditions, hIL16 exists predominantly as a noncovalently linked multimer, but that some IL16 may exist as a monomer. However, only the multimeric form appears to possess chemotactic activity, suggesting that receptor cross-linking may be required for activity. IL16 also induces expression of IL2 receptor (IL2R) and MHC class II molecules on CD4 + T cells. Human and Mouse IL16 show significant cross-species reactivity. Alternative Names: Interleukin 16 protein, IL 16 protein, IL-16, IL16, LCF protein, IL-16 protein, IL-16 protein, Lymphocyte Chemoattractant Factor protein, IL 16