Binding immunoglobulin protein treatment alters cell surface molecule expression and cytokine production. Binding immunoglobulin protein (BiP) treatment alters HLA-DR and co-stimulatory molecule expression and cytokine production in the xenogeneic model of synovial membrane from rheumatoid arthritis patients transplanted into severe combined immunodeficient (SCID) mice. Pieces of human synovial tissue from patients with rheumatoid arthritis were transplanted into SCID mice. After successful engraftment, BiP (10 μg/animal) or human serum albumin (HSA) (10 μg/animal) were administered intravenously, and 12 days later tissue and serum were removed for analysis. (a) Representative immunohistology photomicrographs showing explants of synovial membrane taken from mice injected with HSA (left) or from mice injected with BiP (right). (b) Scattergram showing the concentration of human cytokines IL-4, IL-6 or IL-10 detected in the sera of mice given either HSA or BiP, as detected by ELISA. Each group contained 15 animals.