Blom AB, van Lent PLE, Holthuysen AE, van den Berg WB. Immune complexes, but not streptococcal cell walls or zymosan, cause chronic arthritis in mouse strains susceptible for collagen type II auto-immune arthritis. Cytokine. 1999 Dec;11(12):1046–56.


In this study we investigated mechanisms involved in the chronic character of experimental collagen type II induced arthritis (CIA). We compared the knee joints of mouse strains which are prone to develop this autoimmune disease (DBA/1, B10RIII) with other nonsusceptible mouse strains (C57Bl/6, BALB/c) in their reaction to different stimuli: immune complexes (IC), zymosan and streptococcal cell walls (SCW). Inflammation was evaluated by 99m Tc uptake measurements and in haematoxylin- and eosin-stained knee-joint sections. Passively induced immune complex mediated arthritis (ICA) in knee joints of C57Bl/6 and BALB/c mice, showed moderate cell influx at day 3, whereas at day 7 only minor amounts of inflammatory cells were observed. In contrast, in arthritic DBA/1 and, to a lesser extent, in B10.RIII joints, a tremendous cell influx was observed at day 3 and even at day 14 there was still significant synovitis. In contrast, if arthritis was elicited by intra-articular injection of zymosan or SCW in C57Bl/6 and DBA/1, the course of inflammation was similar in both strains and no chronic inflammation developed. In line with severe arthritis, chemotactic factor production was dramatically enhanced in ICA in DBA/1 mice, and a prolonged production of IL-1 was evident. When IL-1 was neutralized before or during the ICA using specific anti-IL-1, antibodies, inflammation could be blocked completely. Single or multiple injection of IL-1 in the knee joint of C57Bl/6 or DBA/1 showed comparable inflammation, indicating that the chemotactic response per se is comparable in both strains. No prolonged production of IL-1 was found during zymosan or SCW arthritis. Selective removal of macrophages from the synovial intima prior to ICA induction (using clodronate-containing liposomes) prevented the onset of inflammation in C57Bl/6 and DBA/1 mice. It can be concluded that immune complexes, but not zymosan or SCW, cause a more severe and chronic arthritis in mouse strains which are susceptible for collagen type II autoimmune arthritis. This is due to higher and prolonged expression of IL-1 and chemotactic factors, caused by stimulation with immune complexes. The interaction of IC with lining macrophages probably plays a dominant role in development of chronicity.

Clodronate Concentration Total Lipid Concentration Lipid Composition Lipid Mole % Liposome Type Control Liposomes Control Free Clodronate
12.5 mg/ml 23.1 mg/ml EPC/chol 84/16 MLV PBS ND
Animal Description Clodronate Dose Dosing Method/Site Target Phagocytes Systemic Dosing? Systemic Results
C57BL/6, DBA/1, male, 8-12 w 75 µg/6 µl intra-articular/knee synovial no N/A


  1. Liposome prep method cited— van Lent PL, van den Hoek AE, van den Bersselaar LA, Spanjaards MF, van Rooijen N, Dijkstra CD, et al. In vivo role of phagocytic synovial lining cells in onset of experimental arthritis. Am J Pathol. 1993 Oct;143(4):1226–37.
  2. Experimental timeline

    No explanation as to why clodronate is 2.5X more concentrated than reported in other papers. No mention of change in prep method.

  3. Mice were given intra-articular injections of clodronate liposomes in one knee while either PBS or PBS liposomes were injected into the contralateral knee.
  4. 7 d post-treatment, at the time of maximal macrophage depletion, poly-lysine-lysozyme conjugate was dosed intra-articularly 16 h post-intra-articular injection of rabbit anti-lysosome polyclonal Ab to induce immune-complex-mediated arthritis (ICA).
  5. 2 d post-induction of arthritis, mice were sacrificed for histiology or injected with 99m Tc followed by γ-counting of the knee 30 minutes later.


  1. The authors reported a 57% reduction in joint swelling as measured by 99m Tc uptake in synovial macrophage-depleted C57BL/6 mice and 58% reduction in DBA/1 mice.
  2. No other experiments related to clodronate liposomes were reported in this paper.