Variations in Suppressor Molecule <Emphasis Type="Italic">CTLA-4</Emphasis> Gene Are Related to Susceptibility to Multiple Myeloma in a Polish Population

Various phenotype and functional T-cell abnormalities are observed in multiple myeloma (MM) patients. The aim of this study was to investigate the association between polymorphisms in the gene encoding cytotoxic T-lymphocyte antigen-4 (CTLA-4), a negative regulator of the T-lymphocyte immune response and susceptibility to multiple myeloma in a Polish population. Two hundred MM patients and 380 healthy subjects were genotyped for the following polymorphisms: CTLA-4c.49A>G, CTLA-4g.319C>T, CTLA-4g.*642AT(8_33), CT60 (CTLA-4g.*6230G>A), Jo31 (CTLA-4g.*10223G>T). Our study is the largest and most comprehensive evaluation to date of the association between genetic polymorphisms in the CTLA-4 molecule and multiple myeloma. It was found that CTLA-4c.49A>G[G], CT60[G], and Jo31[G] alleles were more frequently observed in MM patients than in controls (0.50 vs. 0.44, p = 0.03, 0.65 vs. 0.58, p = 0.04, and 0.63 vs. 0.57, p = 0.03, respectively). Moreover, the haplotype CTLA-4c.49A>G[G], CTLA-4g.319C>T[C], CTLA-4g.*642AT(8_33) [8], CT60[G], Jo31[G] including all susceptibility alleles increases the risk of MM about fourfold (OR: 3.79, 95%CI: 2.08–6.89, p = 0.00001). These findings indicate that genetic variations in the CTLA-4 gene play role in susceptibility to multiple myeloma and warrant further investigation through replication studies.     

Natural killer (NK) activity in normal donors undergoing leukapheresis

The effect of leukapheresis performed with intermittent flow blood separator on normal donors NK activity is presented. There was statistically significant decrease of NK activity immediately after leukapheresis (p less than 0.001) which did not return to predonation values 1 day after leukapheresis (p less than 0.05), however, none of the donors values fell outside the normal range. It seems that NK cells are not as quickly replaced as T lymphocytes.     

Delayed hypersensitivity reactions in patients with acute leukemias and blastic crisis of chronic granulocytic leukemia

Delayed hypersensitivity reactions were studied in 34 patients with acute leukemias and 13 patients in blastic crisis of chronic granulocytic leukemia during the course of the disease. All patients were skin tested with PPD, Candida antigen, SK/SD and DNCB. A positive correlation existed in majority of patients between the response chemotherapy and delayed hypersensitivity reactions in the tested patients.     

Lack of association between an exon 1 CTLA-4 gene polymorphism A(49)G and multiple sclerosis in a Polish population of the Lower Silesia region

Multiple sclerosis (MS) a chronic inflammatory demyelinating disease of the central nervous system is believed to have a T cell-mediated autoimmune etiology. The cytotoxic T lymphocyte antigen 4 (CTLA-4) gene is a strong candidate for the involvement in autoimmune diseases because CTLA-4 plays an important role in the downregulation of the early and late stages of T cell activation and the maintenance of peripheral T cell tolerance. To examine the genetic association of the CTLA-4 gene locus with MS, we analyzed an exon 1 CTLA-4 gene polymorphism A(49)G in 102 unrelated Polish MS patients in the Lower Silesia region and 101 age- and sex-matched healthy subjects. The distribution of CTLA-4 exon 1 A(49)G genotype, phenotype and allele frequencies did not differ between patients with MS and healthy subjects.     

The significance of Treg cells in defective tumor immunity

Regulatory T cells (Treg) enriched in FoxP3+, glucocorticoid-induced TNF receptor+, and cytotoxic T-lymphocyte-associated antigen-4+ exert a potential to suppress effector T cells in the periphery. These cells exist in markedly higher proportions within tumor-infiltrating lymphocytes, peripheral blood lymphocytes, and/or regional lymph node lymphocytes of patients with cancer and their frequencies are suggested to be strongly related to tumor progression and inversely correlated with the efficacy of treatment. Tumor-specific Treg cells require ligand-specific activation and cell-to-cell contact to exert their suppressive activity on tumor-specific effector cells (CD8+ cytotoxic T lymphocytes and CD4+ Th cells), which includes decreased cytotoxity, proliferation, and Th1 cytokine secrection. Depletion or blockade of Treg cells can enhance immune protection from tumor-associated antigens that are expressed as self antigens. Recent studies revealed that lymphoma T cells might adopt a Treg profile as well. Studies assessing the influence of chemotherapy on Treg cells have also been included in this review.     

CTLA-4 affects expression of key cell cycle regulators of G0/G1 phase in neoplastic lymphocytes from patients with chronic lymphocytic leukaemia

Previously, we showed that cytotoxic T-lymphocyte-associated antigen 4 (CTLA-4) is overexpressed in chronic lymphocytic leukaemia (CLL) and its expression is correlated with the expression of the major regulators of G1 phase progression: cyclins D2 and D3, and cyclin-dependent kinase inhibitory protein 1 (p27 ^KIP1 ). In the present study, we blocked CTLA-4 on the surface of both CLL cells and normal B lymphocytes to investigate the impact of CTLA-4 on the expression of the mentioned G1 phase regulators. We found that in CLL patients and in healthy individuals, the median proportions of cyclin D2-positive cells as well as cyclin D3⁺ cells significantly decreased following CTLA-4 blockade. Moreover, CTLA-4 blockade led to an increase in the median frequencies of p27 ^KIP1 -positive cells, although this increase was marked only in CLL patients. Our study showed that CTLA-4 affects the expression of the key regulators of G1 phase progression in CLL cells as well as in normal B lymphocytes and may contribute to a better understanding of the role of CTLA-4 in the regulation of G1 phase progression.