Release of elastolytic activity from human monocytes and granulocytes in vitro by immune complex stimulation

Elastase from phagocytes are neutral proteolytic enzymes and potent destructors of elastic fibres, proteoglycan and collagen. Using soluble 3H-elastin as substrate in a cell culture assay we examined the ability of live, adherent human blood neutrophils and monocytes to release elastolytic activity following immune complex (IC) stimulation. While monocytes increased their elastolysis 2 1/2 times in response to IC (p less than 0.01), neutrophils did not but released lactoferrin and produced superoxide. Both cell types could be stimulated by phorbol myristate acetate (PMA) to increase elastolysis (p less than 0.02) and produce superoxide. Thus, when in contact with the elastin substrate, the in vitro response of monocytes and neutrophils to IC differed with respect to elastolytic release. These findings might be of interest in the understanding of cartilage destruction in immunocomplex-mediated diseases such as rheumatoid arthritis.