Chemotaxis of radiolabeled equine neutrophils

A method for the isolation of equine neutrophils was developed using metrizamide cushions. A purity of greater than 95% was routinely obtained with greater than 90% viability. These cells were radiolabeled and tested for their chemotactic response in Boyden chambers to zymosan-activated equine serum, the partially purified equine complement component C5a, and formyl-L-methionyl-L-leucyl-L-phenylalanine. The time and ionic requirements for chemotaxis of radiolabeled equine neutrophils were investigated and maximal movement was observed at 2 hours' incubation and 1.0 mM Ca and 0.5 mM Mg. Dinitrophenol in a concentration range of 10(-2) to 10(-6) M also inhibited cell movement. A Zigmond-Hirsch checkerboard assay demonstrated the pronounced chemotactic activity of zymosan-activated equine serum and the partially purified equine C5a. The equine neutrophil did not respond to formyl-L-methionyl-L-leucyl-L-phenylalanine.