Unresponsiveness of peripheral T cells induced by apoptotic bodies derived from autologous T cells

Several reports described the dose-dependent effect of Staphylococcus aureus enterotoxin B (SEB) regarding both levels of apoptosis and anergy of T cells. We investigated here whether T-cell apoptosis induced with SEB causes unresponsiveness of naive T cells. Apoptotic bodies were isolated from human T cells stimulated with antigen-presenting cells (APCs) and SEB by the continuous density gradient centrifugation method. When naive T cells were stimulated with APCs and SEB in the presence of apoptotic bodies, their proliferation was dose dependently suppressed and their TCRs were less downregulated than those of T cells stimulated without apoptotic bodies. Furthermore, those T cells were predisposed not to respond to restimulation with fresh APCs and SEB in the absence of apoptotic bodies. These results, taken together with the observation of tight binding of apoptotic bodies to APCs, imply that T cells stimulated in the presence of apoptotic bodies may undergo unresponsiveness due to interruption of contact with APCs.