Cleavage of IgG by elastase-like protease (ELP) of human polymorphonuclear leukocytes (PMN): isolation and characterization of Fab and Fc fragments and low-molecular-weight peptides. Stimulation of granulocyte function by ELP-derived Fab and Fc fragments.

The elastase-like protease (ELP) from human polymorphonuclear granulocytes (PNM) is able to split human IgG into Fab and Fc-like fragments and smaller peptides. These fragments are similar but not identical to those produced by papain. They differ in their electrophoretical mobility as well as in their molecular weights. Both ELP-Fab and papain-Fab show antigen-binding capacity. In contrast to papain-derived split products of IgG, the ELP-generated Fab and Fc fragments could enhance granulocyte function. Both ELP-Fab and ELP-Fc increase the spontaneous reduction of nitroblue-tetrazolium (NBT) in granulocytes dose-dependent in a homologous as well as in an autologous system. Furthermore, the ELP-derived Fab and Fc induce an active release of ELP by PMN. It could also be demonstrated that Fab as well as Fc increased the peroxidase activity in granulocytes.