Breakdown products of collagen and fibrin. In the stereotyped inflammatory response, neutrophils will be the primary cell at the site soon after injury. Macrophages will become more predominant 12-48 hours after the onset of inflammation. They are mostly derived from blood monocytes. Dying neutrophils release chemotactic factors for macrophages.
Macrophages are long-lived cells, and can divide at the site of inflammation.
Lymphocytes are poorly motile, and usually appear at the site of inflammation later in the process. The primary phagocytic cells are neutrophils and macrophages, although many cells have limited capacity for uptake of particulate material.