INCREASED SYNOVIAL ENDOTHELIUM BINDING AND TRANSENDOTHELIAL MIGRATIONOF MONONUCLEAR-CELLS DURING SALMONELLA INFECTION

Objective. To investigate the adhesion and extravasation capacity of p eripheral blood mononuclear cells (PBMC) and the transport of bacteria l antigens within these cells during Salmonella infection. Methods. Th irteen patients who were part of 2 outbreaks of Salmonella enteritidis infection were included in this study. The capacity of PBMC from thes e patients to bind to vascular endothelium in inflamed synovium was te sted using a Stamper-Woodruff-type frozen-section assay. The same cell s were studied for the presence of Salmonella antigens by immunofluore scence staining. The transendothelial migration of mononuclear cells c ontaining Salmonella or its components through unstimulated endothelia l cell layer was quantified. Results. The capacity of PBMC to adhere t o synovial vessels was significantly increased during Salmonella infec tion (P = 0.0003). Monocytes had a transiently high adhesive state bet ween 2 and 5 weeks after the patients had eaten the contaminated food. The cells containing Salmonella antigens were concentrated in the tra nsmigrated population. Conclusion. During acute Salmonella infection t he increased binding of PBMC to vascular endothelium in inflamed synov ium and enhanced transmigration of PBMC containing Salmonella may be t he key factors leading to transport of bacterial antigens through the endothelial barrier and initiation of arthritis in susceptible individ uals.