The isolation and purification of esterase 1 will be pursued further. If, as expected, an homogeneous enzyme is obtained, attempts will be made to obtain antibodies to the enzyme. The study of the role of activation of enzymes of phospholipid metabolism and particularly the role of arachidonic acid metabolites in the biochemical events leading to granule enzyme secretion and other neutrophil responses will be explored. We will also explore further the nature and function of the receptor on the neutrophil membrane that reacts with synthetic chemotactic factors. We will attempt to define further the nature and role of the two changes in calcium translocation in the neutrophil induced by the chemotactic factors.