Staphylococcus aureus Cowan Strain 1 activation of B-chronic lymphocytic leukaemia cells augments the response to CD40 stimulation

The signals involved in regulating the proliferation, differentiation and s urvival of B-chronic lymphocytic leukemia (B-CLL) cells are fully understoo d. B-CLL cells have been found to respond poorly to various activation sign als and only after successful Epstein-Barr virus (EBV) transformation has i t been possible to maintain such cells in long-term cultures. In this work we describe a new method to activate and induce proliferation in B-CLL cell s and to maintain such cells in long-term culture for longer than 1 month. We used a combination of protocols in an attempt to mimic some of the signa ls of a thymus-dependent immune response. The B-CLL cells were first activa ted with Staphylococcus aureus Cowan strain 1 (SAC) particles plus thioredo xin (Trx), followed by stimulation with interleukin (IL)-2+Trx. This treatm ent primed the cells for further stimulation with anti-CD40 monoclonal anti body (MoAb) presented on irradiated CD32L cells (the CD40-system) or solubl e CD40 Ligand, and a combination of Trx and cytokines (IL-4+IL-10), which a llowed the cells to be maintained for up to 1 month with preserved viabilit y and a variable rate of proliferation. However, induced proliferation of t he B-CLL cells was limited to approximate to 1 month, suggesting that addit ional signals are required to facilitate further proliferation.