Ligand-dependent Release of Active Neutrophil Collagenase

The amount of active neutrophil (PMN) collagenase released extracellularly is dependent on the PMN-activating ligand. Neutrophils stimulated with soluble ligands, including FMLP, platelet-activating factor, or heat-aggregated IgG, released very little active collagenase, in contrast to cells stimulated with opsonized zymosan or surface-bound IgG. However, opsonized zymosan and surface-bound IgG did not differ appreciably from soluble ligands in effecting PMN production of superoxide, release of the specific granule component lactoferrin, or total (latent plus active) collagenase release, which suggests that there is more efficient collagenase activation during PMN stimulation with surface-bound ligands. These results suggest a role for surface (cartilage)-bound IgG in the release and activation of human neutrophil collagenase in the joints of patients with rheumatoid arthritis.