Superantigen-induced CD4 memory T cell anergy. I. Staphylococcal enterotoxin B induces Fyn-mediated negative signaling

► A bacterial toxin (SEB) causes memory CD4 T cell inactivation (anergy). ► We show that anergy is dependent upon activation of Fyn kinase. ► Inhibition or loss of Fyn kinase prevents anergy. ► We show that Fyn associates with c-Cbl in response to SEB. ► Fyn/c-Cbl complexes prevents ZAP-70 from binding to the TCR/CD3 complex.