Leukaemic T Cells from Patients with Chronic Lymphocytic Leukaemia of T‐Cell Origin Respond to Staphylococcus aureus Enterotoxin Superantigens

We investigated the in vitro responsiveness of peripheral blood lymphocytes from two patients with T‐cell chronic lymphocytic leukaemia (T‐CLL) to Staphylococcus aureus enterotoxin (SE) superantigens. T‐cell receptor (TcR) αβ(Vβ 7.1)‐expressing CD4+ leukaemic T cells from patient HE (white blood cell count 480,000/μl) proliferated in response to SEA and, only at 1000‐fold higher concentrations, to SEB, SED, and SEE. CD4+ CD8+ TcRαβ (Vβ 12.1)‐expressing leukaemic T cells from patient KO (white blood cell count 120,000/μl) were activated by SEB but not by the other tested SEs. In both instances, the activation of leukaemic T cells by SE was dependent on the presence of HLA‐DR+ cells. Southern blot analysis of TcRβ gene rearrangement confirmed that the proliferating cells were derived from the leukaemic T‐cell clone and not from contaminating normal T cells. These data indicate that leukaemic T cells from patients with T‐CLL exert a clonally variable responsiveness to SE superantigens. We conclude that recognition of specific antigen and subsequent signal transduction can be initiated via the TcR of leukaemic T‐CLL cells.