Immune system initial response
On the contrary it's not neutrophils that initially recognize a threat, but rather distressed epithelium, and immune cells like DCs or macrophages that are already distributed in the tissue that recognize pathogen- or damage-associated molecular patterns (see PAMPs and DAMPs). The primary response to these patterns is the secretion of cytokines.

Among the many cytokines secreted include a subset known as chemokines, from the Greek work for movement. The combination of chemokines and cytokines induce chemotaxis of immune cells circulating in the blood, such as neutrophils, by telling these cells that the nearby tissue is inflamed. IL-1ß, IL-6 and CXCL2 are examples of neutrophil attractants secreted by macrophages and monocytes. Complement fragments like C5a are also known to induce an inflammatory response, inducing the secretion of these molecules.