T-Cells from CLL patients

T cells may have a role in sustaining the leukemic clone in chronic lymphocytic leukemia (CLL). In this study, we have examined the ability of T cells from CLL patients to support the survival of the leukemic B cells in vitro. Additionally, we compared global gene expression of T cells from indolent CLL patients with healthy individuals and multiple myeloma (MM) patients. Apoptosis of purified CLL cells was inhibited in vitro when cocultured with increasing numbers of autologous T cells (p<0.01) but not with normal donors. The anti-apoptotic effect exceeded that of the antiapoptotic cytokine IL-4 (p=0.02) and was greater with CD8+ T cells than with CD4+ cells (p<0.05). The effect depended mainly on cell-cell contact although a significant effect was observed in transwell experiments (p<0.05). Additionally, about 356 genes involved in different cellular pathways were deregulated in T cells of CLL patients compared to healthy individuals and MM patients. The results of gene expression profiling was verified for 7 genes (KLF6, TRAF1, CCL4, CCL5, RANTES, XCL1 and XCL2) using qRT-PCR and immunoblotting. Our results demonstrate that CLL-derived T cells can prevent apoptosis of leukemic cells and have altered expression of genes that may facilitate survival of the leukemic clone. Peripheral blood was collected by venipuncture from CLL patients, multiple myeloma (MM) patients and age-matched healthy individuals with informed consent and approval of the local Ethics Committee in keeping with the Helsinki declaration on the use of human subjects for research.