CAPSULAR POLYSACCHARIDE TYPE-5 AND TYPE-8 OF STAPHYLOCOCCUS-AUREUS BIND SPECIFICALLY TO HUMAN EPITHELIAL (KB) CELLS, ENDOTHELIAL-CELLS, ANDMONOCYTES AND INDUCE RELEASE OF CYTOKINES

In order to examine the possible implication of capsular polysaccharid e (CP) types 5 and 8 (CP5 and CP8) from Staphylococcus aureus in the p athological mechanism associated with staphylococcal infections, we te sted the immunomodulatory effects of CP5 and CP8 on human epithelial K B cells, endothelial cells, and monocytes, Using biotinylated CP5 and CP8, we provide evidence that both CPs bind to KB cells, endothelial c ells, and monocytes in a dose- and calcium-dependent manner through sp ecific interactions. These results were confirmed by competition exper iments using soluble cell extracts. Furthermore, we show that CPs bind to identical cell membrane receptors on all three types of human cell s and that human normal serum contains a factor(s) which inhibits the binding of both CPs to human KB cells, endothelial cells, and monocyte s, The ability of CP5 and CP8 to stimulate the production of cytokines by the human cells was then examined. CP5 and CP8 trigger KB cells to produce interleukin-8 (IL-8); endothelial cells to produce IL-8 and I L 6; and monocytes to produce IL-8, IL-6, IL-1 beta, and tumor necrosi s factor alpha, The release of cytokines by all three types of cells i s time dependent and dose dependent, and the tumor necrosis factor alp ha production by monocytes is not affected by the addition of polymyxi n B. We further confirm that human normal serum inhibits the immunomod ulatory effects of both polysaccharides on each kind of cell, These re sults confirm that S. aureus CPs act as bacterial adhesins having immu nomodulatory effects for human cells.