Anti-inflammatory effect of granulocyte and monocyte adsorption apheresis in a rabbit model of immune arthritis

In active rheumatoid arthritis, large numbers of granulocytes and macrophages are found in the inflamed joints. These leucocytes can promote inflammation and tissue injury by releasing inflammatory cytokines, proteinases and oxygen derivatives. To see if granulocyte and monocyte (GM) depletion produces anti-inflammatory effect, GM adsorption apheresis was performed in rabbits with immune arthritis by using a column (Adacolumn) filled with cellulose diacetate beads (G-1 beads) as adsorptive carriers which selectively adsorb CD11b positive GMs. Injection of ovalbumin into the knee joints of ovalbumin-sensitized rabbits caused a marked increase in peripheral blood leucocytes, joint swelling, increased granulocyte adhesion to G-1 beads and elevated TNF-alpha production by peripheral blood mononuclear cells (PBMC). When rabbits received a 60 min adsorption apheresis, there was suppression of CD11b positive leucocyte infiltration into the joint and reduced joint swelling (P < 0.01) compared with controls. Additionally, there was a significant (p < 0.01) suppression of TNF-alpha production by PBMC in the post column blood. These results suggest that GM depletion may serve as a non-pharmacological strategy to modify inflammatory disorders.