Medizin - Open Access LMU - Teil 07/22 Archiv

Tissue kallikrein is an enzyme that forms the vasoactive peptide kallidin from an endogenous substrate L-kininogen. Tissue kallikrein has been identified in joint fluids and in inflammatory infiltrates within synovial membranes. It is suggested that tissue kallikrein and kinins have an important role in synovitis and joint damage. Immunoreactive tissue kallikrein and amidase activity were both measured in the synovial fluid of 24 patients with rheumatoid arthritis (RA) and 12 with osteoarthritis (OA). Active enzyme concentrations were higher in RA than in OA and correlated well with the lysosomal enzymes beta-glucuronidase and lactate dehydrogenase. Both total immunoreactive tissue kallikrein and the proenzyme values were similar in RA and OA. Tissue kallikrein was localised by immunocytochemistry to the polymorphonuclear leucocytes present in the synovial fluid and membranes of patients with RA.

Despite a high concentration of serum proteins and intact phagocytes peritonitis exudates contain a large number of viable, pathogenic bacteria. The reason for this biological paradox is unknown. Our investigations reveal a pronounced defect in humoral opsonization of foreign particles in peritonitis exudate. We evaluated a modified chemiluminescence system allowing the determination of opsonic activity in serum and exudate. In serum we found a close correlation between opsonic activity and immunologically measurable levels of C3-complement and IgG. In purulent peritonitis exudates, however, the actual opsonizing activity was much less than expected according to the opsonin concentrations. We found a pronounced difference between immunologically determined opsonin levels and impaired opsonic function. Employing crossed immunoelectrophoresis massive C3-splitting into smaller fragments could be demonstrated in peritonitis exudates. In these exudates we found very high concentrations of granulocyte proteolytic (elastase) and oxidative (myeloperoxidase) enzymes which may lead to a functional destruction of opsonins followed by impaired opsonization in peritonitis exudate. The great number of bacteria and foreign particles in addition can cause a pronounced physiological consumption of complement components. The almost complete breakdown of intact C3-complement in intraabdominal exudate explains the deficient host defence in patients with severe peritonitis.