Inflammation-induced changes in serum modulate chicken macrophage function

Inflammation-induced changes in serum protein profiles and the effects of such serum on a chicken macrophage cell line HD11 were studied to find whether the changes in serum affect cellular immunity. Four-week-old male broiler chickens were injected subcutaneously with either olive oil or 50% croton oil mixed in olive oil to induce inflammation. The birds were bled at 48h after injection, and serum protein profiles were compared using sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and densitometric evaluation. At 48h post-injection the serum from croton oil-injected birds showed distinct changes in protein profiles characterized by a selective increase or decrease in levels of several serum proteins. The protein bands which showed increases had relative molecular weights (Mr) corresponding to 65kilo Daltons (kD), 42kD, and two or more proteins with Mr> or =200kD. The levels of serum albumin (49kD), and a 56kD protein were reduced in croton oil-injected birds. The modulating effects of such serum on HD11 cells were studied using bacterial lipopolysaccharide (LPS) or phorbol myristate acetate (PMA) induced functional activation of these cells. The LPS-induced interleukin-6 (IL-6) production by HD11 cells was not affected by the presence of either olive oil-treated control or croton oil-treated inflammatory serum but nitrite production was enhanced by the inflammatory serum. Similarly, inflammatory serum also enhanced PMA-induced respiratory burst measured using dichlorofluorescein diacetate (DCF-DA) oxidation mediated by reactive oxygen intermediates. These results suggest that inflammatory serum can modulate macrophage function by influencing the production of reactive oxygen and nitrogen species which could affect their phagocytic and bactericidal activities.