ORTHOTOPIC IMPLANTATION OF INFLAMED SYNOVIAL TISSUE FROM RA PATIENTS INDUCES A CHARACTERISTIC ARTHRITIS IN IMMUNODEFICIENT (SCID) MICE

The objective of this work was to study in more detail the human/murin e SCID arthritis model with special emphasis on characteristic feature s initiated by rheumatoid arthritis (RA) synovial membrane (SM) as com pared to appropriate control tissues. Small tissue samples from RA-SM, healthy lymph node, healthy SM, and granulomatous tissue of human ori gin were implanted into the left knee joint of mice with severe combin ed immunodeficiency (SCID), and the joints were analysed histologicall y after 7 days. In addition, a time course study, including non-invasi ve monitoring by serological parameters (human IgM, IgG, and IL-6) and Tc-99m-scintigraphy, was performed for up to 4 weeks on RA-SM recipie nts. All tissue implants induced transient exudative joint inflammatio n while RA-SM initiated a characteristic arthritis with pannus tissue of high cellular density, erosion, multinuclear giant cells, lining ce ll hyperplasia, fibroblast-like cell layers, chondroideal metaplasia, and fibrin deposits. Significantly elevated levels of human immunoglob ulin and characteristic signs of chronic inflammation persisted for mo re than 4 weeks. We conclude that the hu/mu SCID arthritis with RA-SM implants comprises features of non-specific inflammation which is also transiently seen with control tissues but develops characteristic fea tures of chronic RA-like synovitis thereafter. (C) 1996 Academic Press Limited