T-Lymphocyte Activation Induced by Staphylococcal Enterotoxin Superantigens: Analysis of Protein Tyrosine Phosphorylation

Staphylococcus enterotoxin superantigens (SAgs) have the capacity to strongly activate oligoclonal populations of T lymphocytes expressing T-cell antigen receptors (TCR) that share particular V_β elements. These superantigens stimulate T lymphocytes by binding simultaneously to TCR V_β domains and to major histocompatibility complex (MHC) class II molecules on antigen-presenting cells (APCs) (1 ). Several characteristics distinguish enterotoxin superantigens from conventional antigens: (1) superantigen stimulation, although usually requiring the presence of MHC class II molecules on APCs, is not restricted to one MHC allele. Therefore, a priori any MHC class II positive cell would be suitable as superantigen presenting cell. (2) Processing of superantigens into antigenic peptides is not necessary. Therefore, just short incubations are necessary to pulse APCs with enterotoxin superantigens.