The tissue architecture of synovial membranes in inflammatory and non-inflammatory joint diseases. I. The localization of the major synovial cell populations as detected by monoclonal reagents directed towards Ia and monocyte-macrophage antigens.

Utilizing monoclonal reagents directed towards antigens of the monocyte-macrophage lineage and Ia antigens, the tissue architecture of synovial membranes obtained from patients with non-inflammatory joint diseases and patients with rheumatoid arthritis was studied. Emphasis was placed on the localization of the type I, type II and type III synoviocytes that previously had been defined by their cell surface phenotype with regard to the expression of monocyte-macrophage lineage (M theta) and Ia antigens as well as by their phagocytic capacity or the ability to produce glycosaminoglycans. In patients with non-inflammatory joint diseases, cells with the M theta + Ia+ (type I) phenotype constituted the majority of synoviocytes immediately adjacent to the joint cavity; cells with this phenotype were also scattered in the subsynovial tissue and in the perivascular regions. The fibroblastoid type III cells defined by the absence of both M theta and Ia antigens formed the major cell population in the subsynovial tissue in this patient group. In patients with rheumatoid arthritis, the Ia+ M theta + cells were present in a characteristic double configuration forming an intensely positive layer adjacent to the intra-articular space followed by an Ia- M theta - layer that again was succeeded by an intensely Ia+ M theta + layer. Large numbers of synoviocytes bearing M theta + Ia+ antigens were also demonstrated in the diffusely inflamed subsynovial tissue, in the perivascular regions as well as around and within lymphoid infiltrates.(ABSTRACT TRUNCATED AT 250 WORDS)