ABSTRACT
B cells currently are not viewed as being capable of producing granzyme B or being cytotoxic. We found that B-chronic lymphocytic leukemia (B-CLL) cells treated with interleukin-21 (IL-21) produce low levels of granzyme B. The addition of either CpG oligodeoxynucleotide (ODN) or anti-B-cell-receptor antibody (anti-BCR) to IL-21 results in enhanced production of functional granzyme B by B-CLL cells. B-CLL cells treated with IL-21 and CpG ODN undergo apoptosis and are able to induce apoptosis of untreated bystander B-CLL cells. This effect can be inhibited by anti-granzyme B antibody. Benign human B cells, Epstein-Barr virus (EBV)-transformed lymphoblasts, and many standard lymphoma cell lines produce high levels of granzyme B in response to IL-21 and anti-BCR. Our results suggest that the ability to induce production of functional granzyme B by B cells could open new approaches to the therapy of B-CLL and other B-cell malignancies. Our findings also have significant implications for our understanding of the role of B cells for immune regulation and for a variety of immune phenomena, including cancer immunity, autoimmunity, and infectious immunity.
Subject(s)
Interleukins/pharmacology , Leukemia, Lymphocytic, Chronic, B-Cell/enzymology , Leukemia, Lymphocytic, Chronic, B-Cell/immunology , Serine Endopeptidases/biosynthesis , Apoptosis/drug effects , B-Lymphocytes/drug effects , B-Lymphocytes/enzymology , B-Lymphocytes/immunology , Cells, Cultured , Granzymes , Humans , In Vitro Techniques , Interleukin-21 Receptor alpha Subunit , Leukemia, Lymphocytic, Chronic, B-Cell/drug therapy , Lymphocyte Activation/drug effects , Lysosomal-Associated Membrane Protein 1/metabolism , Oligodeoxyribonucleotides/pharmacology , Receptors, Interleukin/genetics , Receptors, Interleukin-21 , Recombinant Proteins/pharmacology , T-Lymphocytes, Cytotoxic/drug effects , T-Lymphocytes, Cytotoxic/enzymology , T-Lymphocytes, Cytotoxic/immunology , Tumor Cells, Cultured , Up-Regulation/drug effectsABSTRACT
Immunostimulatory CpG-containing oligodeoxynucleotides (CpG ODN) have a number of effects on B cells, including upregulation of immunogenic molecules, and, therefore, appear attractive as potential components of immunotherapy for B cell chronic lymphocytic leukemia (B-CLL). Previous in vitro studies investigating the effect of CpG ODN on B-CLL cells used serum-low conditions and did not account for the longer-half life of CpG ODN in vitro. The present study was designed to explore how the presence of serum and exposure time affect CpG ODN-mediated changes on B-CLL cells. The optimal concentration for CpG ODN-mediated effects in the presence of 100% serum or plasma was higher (10-20 microg/ml) than for serum-low conditions. Maximal CpG ODN-mediated effects required the presence of ODN for no longer than 3 hours. The inhibition of CpG ODN-mediated effects by serum correlated with lower uptake of ODN into B-CLL cells in the presence of serum. A threshold effect on biologic response was observed, with a given amount of ODN internalized, resulting in phenotypic changes. In conclusion, systemic short-term application of CpG ODN appears to be sufficient to induce phenotypic changes, but higher doses of CpG ODN than previously thought may be necessary because of inhibition of their uptake by serum.
Subject(s)
CpG Islands/genetics , Gene Transfer Techniques , Leukemia, B-Cell/genetics , Leukemia, Lymphoid/genetics , Oligonucleotides/chemistry , Culture Media, Serum-Free/pharmacology , Dose-Response Relationship, Drug , Flow Cytometry , Humans , Immunophenotyping , Immunotherapy/methods , Phenotype , Time Factors , Up-RegulationABSTRACT
Immunostimulatory oligodeoxynucleotides (IS ODN) can mediate a number of immunologic effects. We previously demonstrated that treatment of B cell chronic lymphocytic leukemia (B-CLL) cells with one class of IS ODN, CpG ODN, alters their phenotype and increases their immunogenicity. Here, we demonstrate that in contrast to the classic understanding of CpG ODN as inhibitors of B cell apoptosis, IS ODN including CpG ODN induce apoptosis in B-CLL cells. It is important that these changes are seen not only with CpG ODN but with ODN that lack the classical CpG motif. B-CLL cells from 20 subjects were treated in vitro with IS ODN for up to 7 days. IS ODN treatment resulted in increased numbers of apoptotic cells in 13 out of 20 B-CLL samples. IS ODN enhanced apoptosis in samples with 13q deletion as a single aberration and had a heterogeneous effect on apoptosis in samples with other aberrations including 17p deletion, 11q deletion, or trisomy 12. Induction of apoptosis did not correlate with expression of the CpG ODN receptor Toll-like receptor 9. Apoptosis was dependent on the activation of caspases and was accompanied by up-regulation of CD95/Fas and its ligand. We conclude that IS ODN including CpG ODN can induce apoptosis of most B-CLL samples. The ability of IS ODN to induce apoptosis differs based on cytogenetic status. Up-regulation of CD95/Fas may play a role in IS ODN-induced apoptosis of B-CLL.
