DEFECTIVE DEPLETION OF CD45-NULL THYMOCYTES BY THE STAPHYLOCOCCUS-AUREUS ENTEROTOXIN-B SUPERANTIGEN

The development of a normal T-cell repertoire is critically dependent on the negative and positive selection events which occur at the CD4()CD8(+) (double positive, DP) stage of thymic development. Depending o n the avidity of the T-cell antigen receptor (TCR) for peptides presen ted within the thymus, DP thymocytes are either positively selected fo r maturation to CD4(+)/CD8(+) single positive cells or are depleted by apoptosis. The addition of superantigen to thymocytes within foetal t hymic organ culture (FTOC) mimics the negative selection signal of pot entially autoreactive thymocytes and induces the responding population of thymocytes to apoptose. Here we present evidence that the transmem brane phosphotyrosine phosphatase CD45 critically regulates TCR-induce d signals in thymic differentiation and present data to show defective depletion of CD45-null transgenic TCR-V beta 8 DP thymocytes in FTOC by the Staphylococcus aureus Enterotoxin B (SEE) superantigen. (C) 199 6 Elsevier Science B.V.