Submitted to: American Journal of Veterinary Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 4, 1997
Publication Date: N/A
Interpretive Summary: Adhesion molecules are involved in guiding neutrophils to sites of infection in the udder of cows. Neutrophils are a type of white blood cell involved in the protection of the udder against infection by mastitis causing bacteria. Normal neutrophil function requires the cooperation and coordination of many cellular activities within the neutrophil and cells of the vascular system. The free flowing neutrophil begins the process by rolling along the vessel wall. This first step in migration from blood to milk is mediated by an adhesion molecule called L-selectin located on the surface of neutrophils. During rolling along the vessel wall, L-selectin molecules are shed from the surface of neutrophils and can be found in the blood stream. Low blood concentrations of L-selectin are found during certain disease states. Scientists in the Immunology and Disease Resistance Laboratory, USDA-ARS, Beltsville, Maryland have recently produced antibodies to bovine L-selectin. These antibodies will be used to develop diagnostic tests that will aid in the early detection of not only mastitis but other economically important animal diseases.
Two anti-bovine neutrophil monoclonal antibodies (MAB) were characterized with regard to their effects on bovine neutrophil function and their binding antigens on the cell surface of bovine neutrophils. MAB 11G10 and 2G8 inhibited chemotactic activity of bovine neutrophils and up-regulated the amplitude of native chemiluminescence. Crosslinking both MAB with second antibody induced a rapid rise of intracellular free calcium concentration. The binding of both MAB to neutrophils treated with trypsin was increased compared to controls. Neutrophils treated with phosphatidylinositol specific phospholipase C had a decreased binding density of both MAB. The binding of both MAB to neutrophils from calves with bovine leukocyte adhesion deficiency was lower when compared to neutrophils from normal calves. Immunoprecipitation revealed that 90 to 96 kd antigens (under reducing conditions) were recognized by both MAB. Immunoblotting experiments proved that MAB 11G10 and 2G8 recognized L-selectin molecules with a molecular mass of 120 kd on bovine neutrophils under non-reducing conditions. Results will facilitate the development of useful reagents for studying cell surface receptors on bovine neutrophils and the design of new therapeutic strategies to combat mastitis.