T-Cells from CLL patients. Homo sapiens

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. Overall design: 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.