Functions of purified mouse neutrophils isolated from gelatin sponges.

When sterile gelatin sponges are implanted under the skin of a mouse and retrieved 6 hr later, approximately 10(6) neutrophils per mouse, in a 98-99% pure population, may be retrieved by simply squeezing and rinsing the sponges. These neutrophils behave similarly to peritoneal exudate neutrophils in chemotaxis and phagocytosis assays, but are bacteriostatic rather than bactericidal. The sponge method yields substantially more neutrophils than could be obtained by exsanguinating the mouse and isolating blood neutrophils, and a 5-fold purer population than is normally obtained by passage of peritoneal exudate cells over Ficoll. In addition, sponge-elicited neutrophils may be ready for use within a half hour after removal from the mouse, without being exposed to osmotic shock or Ficoll.