To examine expression of adhesion molecules within human synovial xenografts in vivo after injection of human cytokines or peripheral blood mononuclear cells (PBMC).
Rheumatoid synovium was transplanted into subcutaneous pouches in the ears of severe combined immunodeficient (SCID) mice. Tumor necrosis factor-alpha (TNF-alpha), interleukin 1beta (IL-1beta), or PBMC were injected into the xenografts. The grafts were assessed by immunohistochemistry and quantitative video image analysis.
TNF-alpha, IL-1beta, and concanavalin A activated PBMC increased the expression of vascular cellular adhesion molecule 1 and intercellular adhesion molecule 1 significantly on vessels and nonvascular synovial cells compared with injection of medium only. Vascular expression of E-selectin, but not of MHC Class II, was also increased. These stimuli also induced the migration of murine leukocytes into the xenografts.
Rheumatoid synovial xenografts in SCID mice respond by upregulation of adhesion molecule expression when challenged in vivo with proinflammatory cytokines or activated PBMC.