Complement in acute and chronic arthritides: assessment of C3c, C9, and protectin (CD59) in synovial membrane.

OBJECTIVES: To investigate the role of complement cascade induced damage and protection against it in acute arthritides compared to rheumatoid arthritis and other chronic joint derangements. METHODS: C3c, C9, and protectin (CD59) were examined by avidin-biotin-peroxidase complex staining. RESULTS: Marked deposits of C3c and C9 were found in synovial vasculature and intercellular matrix of the lining in rheumatoid arthritis and in acute arthritides (including bacterial, reactive, and osteoarthritis flare up). Furthermore, protectin was not visible in synovial lining cells and was relatively weakly expressed in stromal and endothelial cells in rheumatoid arthritis; also in acute arthritides protectin expression was weak. In contrast, C3c and C9 deposits were not found in chronic conditions associated with degenerative diseases (osteoarthritis and osteochondritis dissecans) or mechanical causes (patellar luxation and a ruptured meniscus), in which also the protectin expression was prominent in synovial lining, endothelial and some stromal cells. CONCLUSIONS: Activation of the complement in rheumatoid arthritis and in acute arthritides seems to be associated with a decreased protection of synovial cells against cellular effects and lysis mediated by membrane attack complex.

Activation of the complement system and adverse effects of biodegradable pins of polylactic acid (Biofix) in osteochondritis dissecans.

Biodegradable pins of polyglycolic acid (PGA) or polylactic acid (PLA) have been used in the treatment of fractures and osteotomies during the past 5 years. Adverse effects reported have included swelling at the implantation site and sinus formation, considered to represent nonspecific foreign-body reactions. Recent reports, however, have shown severe reactions after intraarticular fracture fixation. Reactions in 2 patients, treated with polylactic pins for osteochondritis dissecans (OCD) in our hospital, prompted the present clinical investigation and further evaluation of the complement-activating potential of polylactic pins. 10 knees underwent arthroscopic fixation of an OCD-lesion with Biofix (PLA) pins. Clinical follow-ups were carried out at 2, 6, and 12 weeks and at 6 and 12 months. Blood samples were collected from 5 patients 9-24 months postoperatively for biocompatibility tests. Quantification of human C5a des Arg was performed with a recently developed sandwich ELISA technique, using neoepitope-specific monoclonal antibodies. 6 knees developed diffuse swelling and a prolonged postoperative course. 2 patients had a particularly prolonged course which could not be attributed to infection. Levels of C5a des Arg in plasma incubated in the presence of polylactic acid were higher than in plasma incubated in the absence of PLA. The high frequency of long-term postoperative inflammatory signs in these knees treated for OCD and the demonstration of a complement activation potential of PLA pins warrant further studies on the biocompatibility of this material. Until more information is available, we do not recommend intraarticular use of PLA pins.