Interaction of polymorphonuclear leukocytes with immune complexes trapped in joint collagenous tissues

The present experiments were designed to investigate in vitro interactions between polymorphonuclear leukocytes (PMN) and rabbit joint collagenous tissues containing trapped immune complexes. Articular cartilages and menisci from antigen-injected and control joints were incubated with normal PMN isolated from rabbit peritoneal exudates or blood. After incubation of cartilage and menisci from antigen-injected joints with PMN, large numbers of PMN became attached to the articular surface. In areas of superficial erosion, the PMN invaded the tissue several cell diameters below the articular surface. Through immunoelectron microscopy, degranulated PMN were observed in scattered areas to phagocytose amorphous material containing rabbit Ig. Following addition of PMN to control tissues, only a few PMN became attached to the articular surface. When tissues from monosodium urate-injected joints were incubated with PMN, these cells were found attached to the surface in moderate numbers, but invasion into the tissues was not seen. These studies indicate that immune complexes trapped in joint collagenous tissues may lead to enhanced release of lysosomal hydrolases.