Dynamics of avian inflammatory response to cross-linked dextran: changes in avian blood leukocyte populations

A model inflammatory compound, cross-linked dextran (Sephadex), which preferentially recruits macrophages, was used to examine shifts in chicken leukocyte distribution and monocyte functional status during the inflammatory response. Following intraperitoneal Sephadex administration, total leukocyte counts were transiently elevated because of a fivefold increase in circulating heterophils (granulocytes). While both heterophils and monocytes may become demarginated, primarily monocytes enter the peritoneal cavity in response to Sephadex. Since leukocyte chemotaxis is an important feature of the inflammatory response, this parameter was analyzed during the recruitment period. The optimum conditions for in vitro chicken mononuclear leukocyte chemotaxis to N-formyl-methionyl-leucyl-phenyl-alanine (FMLP) were defined and compared with those for the chicken macrophage-like cell line, HD11. Mononuclear leukocytes from birds injected 6 or 12 h previously with Sephadex were significantly decreased in chemotactic ability when compared with controls; at 24 h after injection, the response to FMLP had returned to normal. This system offers an opportunity to examine differential effects of inflammatory stimuli upon leukocyte function and distribution.