Activation of neutrophils by immune complexes in synovial fluid contributes to the pathology of rheumatoid arthritis . Chronic activation of neutrophils may also initiate tumour development because some ROI generated by neutrophils damage DNA and proteases promote tumour cell migration. In patient suffering from severe burns , a strong correlation has been established between the onset of bacteremic infection and reduction in the proportion and absolute numbers of neutrophils positive for antibody and complement receptors. Uptake of these oxidized LDL by macrophages is thought to initiate atherosclerosis . Hydrolytic damage to host tissue and therefore chronic inflammatory conditions may occur only when antioxidant and antiprotease screens are overwhelmed.
Antiprotease deficiency is thought to be responsible for the pathology of emphysema .
Although the circulation is rich in antiproteases, these large proteins may be selectively excluded at sites of inflammation because neutrophils adhere hightly to their targets. Oxidative stress may initate tissue damage by reducing the concentration of extracellular antiproteases to below the level required to inhibit released proteases. ANCA are antibodies directed against enzymes that are found mainly within the azurophil or primary granules of neutrophils. There are three types of ANCA that can be distinguished by the patterns they produce by indirect immunofluorescence when tested on normal ethanol-fixed neutrophils. The target antigen is usually proteinase 3.