Immunostimulatory CpG-oligonucleotides induce functional high affinity IL-2 receptors on B-CLL cells: costimulation with IL-2 results in a highly immunogenic phenotype.
OBJECTIVE
CpG-oligodeoxynucleotides (CpG-ODN) have been shown to induce proliferation, cytokine production, and surface molecule regulation in normal and malignant human B cells. In the present study, we investigated the potential of CpG-ODN to induce functional high-affinity receptors in leukemic and normal B cells and the effects of costimulation with IL-2 on proliferation, cytokine secretion, and surface molecule regulation.


METHODS
Highly purified B cells from B-CLL patients and normal controls were stimulated with CpG-ODN with or without IL-2. Expression of CD25 was determined using FACS, and the presence of high-affinity IL-2 receptors was determined by scatchard analysis. Costimulatory effects of IL-2 and CpG-ODN were investigated using proliferation assays, ELISA (IL-6, TNF-alpha), and FACS analysis (CD80, CD86 expression). Reactivity of autologous and allogeneic T cells toward activated B-CLL cells was determined in mixed lymphocyte reactions and Interferon-gamma Elispot assays.


RESULTS
The CpG-ODN DSP30 caused a significantly stronger induction of the IL-2 receptor alpha chain in malignant as compared with normal B cells (p = 0.03). This resulted in the expression of functional high-affinity IL-2 receptors in B-CLL cells, but fewer numbers of receptors with less affinity were expressed in normal B cells. Although addition of IL-2 to CpG-ODN-stimulated cells augmented proliferation in both normal B cells and B-CLL cells, no costimulatory effect on cytokine production or surface molecule expression could be observed in normal B cells. In contrast, TNF-alpha and IL-6 production was increased in B-CLL cells, and the expression of CD80 and CD86 was further enhanced when IL-2 was used as a costimulus. Autologous and allogeneic immune recognition of B-CLL cells stimulated with CpG-ODN and IL-2 was increased compared with B-CLL cells stimulated with CpG-ODN alone.


CONCLUSIONS
Stimulation of B-CLL cells with CpG-ODN and IL-2 might be an attractive strategy for potential immunotherapies for B-CLL patients.
Decker
T
T
IIIrd Department of Medicine and, Technical University of Munich, Munich, Germany.
Schneller
F
F
Kronschnabl
M
M
Dechow
T
T
Lipford
G B
GB
Wagner
H
H
Peschel
C
C
D000276:Adjuvants, Immunologic / Q000494:pharmacology*; D015703:Antigens, CD / Q000235:genetics; D001402:B-Lymphocytes / Q000187:drug effects / Q000276:immunology*; D018122:B7-1 Antigen / Q000235:genetics; D051940:B7-2 Antigen; D005434:Flow Cytometry; D005786:Gene Expression Regulation / Q000187:drug effects / Q000276:immunology; D006801:Humans; D007376:Interleukin-2 / Q000494:pharmacology; D015850:Interleukin-6 / Q000235:genetics; D007700:Kinetics; D015451:Leukemia, Lymphocytic, Chronic, B-Cell / Q000097:blood / Q000276:immunology* / Q000473:pathology; D008562:Membrane Glycoproteins / Q000235:genetics; D009838:Oligodeoxyribonucleotides; D009841:Oligonucleotides / Q000494:pharmacology*; D015375:Receptors, Interleukin-2 / Q000235:genetics*; D012016:Reference Values; D014407:Tumor Cells, Cultured; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics
D000276:Adjuvants, Immunologic; D015703:Antigens, CD; D018122:B7-1 Antigen; D051940:B7-2 Antigen; C497964:CD86 protein, human; C408982:CPG-oligonucleotide; D007376:Interleukin-2; D015850:Interleukin-6; D008562:Membrane Glycoproteins; D009838:Oligodeoxyribonucleotides; D009841:Oligonucleotides; D015375:Receptors, Interleukin-2; D014409:Tumor Necrosis Factor-alpha