Since the sensitivity of B-CLL to treatments is heavily reduced by the microenvironment within the lymphoid organs, in the present study we have analyzed primary cells isolated from 26 B-CLL affected patients (Table 1) co-cultured in the presence of stroma or stimulated with CpG-ODN and CD40L, to mimic the lymph node environment in vitro. The gene discussed is CD40LG; the disease is B-cell chronic lymphocytic leukemia.