The product contains the polyhedrin protein co-crystalized with Human IL-5. IL-5 is hematopoietic growth factor produced by CD4+ Th2 cells, mast cells, eosinophils and NK cells. It is a homodimeric, disulphide-linked protein which, acting via the IL-5 receptor (IL-5R), mediates eosinophil proliferation and activation, as well as stimulating B-cell growth and differentiation into immunoglobulin secreting cells. Human and Murine IL-5 are approximately 70% identical, and show cross-reactivity.