Identification of a New Target in the Interactions between Staphylococcal Enterotoxin B with the Renal Proximal Tubule Epithelial Cells

Abstract

Staphylococcal eneterotoxin B (SEB) a monovalent T cell mitogen and inducer of T suppressor cells, is known to form complexes with the major histocompatibility complex class II and T‐cell receptor in a manner that is quite different from the way the natural ligands bind to the same receptors and direct normal cellular responses it bypasses the normal route of antigen processing by binding as an intact protein to the complex formed by the MHC class II receptor on the antigen‐presenting cell and the T cell receptor.It is estimated that within 90 min. post‐exposure to SEB, >75% of the toxin is cleared to the renal tubule epithelial cells. We hypothesize that SEB binds to these cells using a mechanism that does not include MHCII.Binding assays carried out in vitro in proximal tubule epithelial cells suggests that glycosphingolipids and lipid rafts play a major role in SEB interactions with these cells.CD1d is an MHC class I homologous protein that is present in the plasma membrane lipid rafts and is proposed to be involved in presenting the antigen to the NKT cells.We have studied SEB interactions with the proximal tubule epithelial cells using imaging and direct protein‐protein interaction studies and showed that SEB can interact with CD1d on the proximal tubule epithelial cells.