A novel acute phase marker in cattle: lipopolysaccharide binding protein (LBP)

The host response to infection, the 'acute phase response' is a highly cons erved series of physiological reactions including marked changes in concent rations of plasma proteins. These proteins have been shown to participate i n the immune response to infections. Several recent studies have elevated t he role of acute phase proteins (APPs) as predictive markers in infection. APPs such as serum amyloid A and haptoglobin but not C-reactive protein (CR P) have been identified as markers of inflammation in cattle. In humans, li popolysaccharide (LPS) binding protein (LBP) has certain biological functio ns in host defence and participates in acute phase reactions. We measured p lasma levels of LBP in a group of 20 calves experimentally infected with Gr am-negative Mannheimia haemolytica (Pasteurella) in comparison to haptoglob in, the most widely studied APP in cattle. In infected calves, LBP levels r ose significantly 6 h after infection, reaching a maximum at 24 h. Haptoglo bin concentrations significantly rose after 12 h, and peak responses were m easured 48 h after infection. Thus, LBP may prove to be a diagnostic marker in cattle infection and is faster than haptoglobin in detecting sepsis.