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Background: ROR1 is a receptor tyrosine kinase expressed in chronic lymphocytic leukemia (CLL) and several other malignancies but absent in most adult normal tissues. ROR1 is considered an onco-fetal antigen. In the present study we analysed spontaneous humoral and cellular immunity against ROR1 in CLL patients. Materials and Methods: Antibodies against ROR1 were analysed in 23 patients and 20 healthy donors by ELISA and Western blot. Purified serum IgG from patients was tested for cytotoxicity against CLL cells using the MTT viability assay. A cellular immune response against ROR1 derived HLA-A2 restricted 9 aa and 16 aa long peptides were analysed using peptide loaded dendritic cells co-cultured with autologous T cells from CLL patients (n = 9) and healthy donors (n = 6). IFN-γ, IL-5 and IL-17A-secreting T cells were assessed by ELISPOT and a proliferative response using a H3-thymidine incorporation assay. Results: The majority of CLL patients had antibodies against ROR1. Significantly higher titers of anti-ROR1 antibodies were noted in patients with non-progressive as compared to progressive disease. The extracellular membrane-close ROR1 KNG domain seemed to be an immunodominant epitope. Ten patients with high titers of anti-ROR1 binding antibodies were tested for cytotoxicity. Five of those had cytotoxic anti-ROR1 antibodies against CLL cells. ROR1-specific IFN-γ and IL-17A producing T cells could be detected in CLL patients, preferentially in non-progressive as compared to patients with progressive disease (p<0.05). Conclusion: ROR1 seemed to spontaneously induce a humoral as well as a T cell response in CLL patients. The data support the notion that ROR1 might be a specific neo-antigen and may serve as a target for immunotherapy. [ABSTRACT FROM AUTHOR]

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 leukemic B cells was inhibited in vitro when co-cultured with increasing numbers of autologous T cells ( p < 0.01) but not autologous B and T cells of normal donors. The anti-apoptotic effect exceeded that of the anti-apoptotic cytokine IL-4 ( p = 0.002) and was greater with CD8+ cells ( p = 0.02) than with CD4+ cells ( p = 0.05). The effect was depended mainly on cell-cell contact although a significant effect was also observed in transwell experiments ( p = 0.05). 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 were verified for 6 genes (CCL4, CCL5 (RANTES), XCL1, XCL2, KLF6, and TRAF1) using qRT-PCR and immunoblotting. Our results demonstrate that CLL-derived T cells can prevent apoptosis of leukemic B cells and have altered expression of genes that may facilitate the survival of the leukemic clone. [ABSTRACT FROM AUTHOR]

T-cell dysfunction in B-CLL patients might be attributed to altered expression of components of the TCR/CD3 complex and associated intracellular tyrosine kinases. Four-color flow cytometry was applied to the expression of these molecules as well as the T-cell regulatory cytokines (IFN-gamma and IL-4) in B-CLL patients with indolent and progressive disease. Intracellular levels [mean fluorescent intensity (MFI)] of IFN-gamma and IL-4 in both CD4 and CD8 T cells of both patient groups were significantly higher than in healthy donors. Absolute number of IL-4 producing CD4 T cells in patients with indolent was significantly higher than in healthy donors. The expression level (MFI) of the CD3-zeta chain was higher in patients than in normal donors as well as ZAP-70 in patients with indolent disease as compared to healthy donors and progressive patients. No significant difference was noted in the expression of p56lck, p59fyn, and PI3-kinase between healthy donors and patients or between the patient subgroups. The results indicate multiple T-cell abnormalities especially in indolent-stage B-CLL suggesting a state of chronic and aberrant activation. This information might be of significance when studying the immunobiology of B-CLL as well as developing new therapeutic approaches. [ABSTRACT FROM AUTHOR]