Thalidomide regulation of NF-κB proteins limits Tregs activity in chronic lymphocytic leukemia.

Background: Thalidomide may represent a novel therapeutic strategy in the treatment of chronic lymphocytic leukemia (CLL). Since the activation of nuclear factor kappa B (NF-κB) causes not only malignant transformation and tumor progression, but also allows tumor cells to evade immune surveillance, NF-κB signaling components might constitute a potential target for future therapy in CLL.

Objectives: The current study is an attempt to characterize proteins regulated by thalidomide. Thalidomide's influence on NF-κB proteins and on regulatory T cells (Treg) in CLL was investigated.

Material And Methods: A total of 15 patients with CLL were treated with a combined thalidomide/fludarabine regimen. Peripheral blood mononuclear cells were separated by Ficoll density gradient centrifugation. To evaluate glucocorticoid induced tumour-necrosis-factor-receptor-related protein (GITR) expression in regulatory T cells, cells incubated with anti-CD3, ani-CD4 and anti-CD25 were permeabilized and then stained with anti-FOXP3 and analyzed using flow cytometry. Human TNF enzyme-linked immunosorbent assay (ELISA) was used to determine the tumor necrosis factor (TNF) levels in the serum. To evaluate NF-κB activity, chemiluminescent oligonucleotide-based ELISA was performed.

Results: It was found that thalidomide regulates NF-κB activity differentially, and the activity of certain NF-κB components correlated with TNF levels and T regulatory cell (CD4 + CD25 high GITR + ).

Conclusions: These results might indicate that thalidomide not only regulates TNF but also directly interferes with NF-κB components.