ABSTRACT
Chronic lymphocytic leukemia (CLL) is characterized by the peripheral accumulation of neoplastic B cells and is frequently complicated by the systemic immunosuppression associated with an impairment in B and T lymphocyte activation. We hypothesized that the expression of immune checkpoint suppressors B and T lymphocyte attenuator (BTLA) and cytotoxic T lymphocyte antigen (CTLA-4) is disturbed in both lymphocyte subpopulations in CLL. The expression of CTLA-4 and BTLA mRNA was determined by real-time PCR, while CTLA-4 protein expression (surface or intracellular) was estimated in BTLA+ lymphocytes by flow cytometry. In CLL patients, we observed a higher gene transcript level of BTLA and CTLA-4 than in healthy individuals in both freshly isolated and PMA stimulated B and T cells. Remarkably, lower amounts of both inhibitory proteins were found in peripheral blood (PB) CLL B cells, whereas normal BTLA and elevated CTLA-4 were found in T cells. Consistently, there was a prevalence of CTLA-4+ cells within circulating BTLA+ T cells cells of patients confronting PB healthy cells. After in vitro stimulation, the only change found in CLL patients was a decrease in BTLA expression in B and T lymphocytes. In contrast, healthy lymphocytes responded more vigorously as regards the BTLA and CTLA expression with substantially higher frequency of CD69+ cells under the stimulating condition compared to corresponding cells from the CLL group. Our results indicate that CLL development is associated with the affected expression of BTLA and CTLA-4 checkpoint receptors in PB and its impaired expression might be associated with lowering of the threshold for B cell activation and proliferation, while upregulated CTLA-4 expression in CLL peripheral BTLA+ T cells may contribute to suppressed T cell effector functions. This hypothesis needs to be validated in future studies, which would allow us to explain how the increased or decreased expression of these molecules affects the cell function.
Subject(s)
CTLA-4 Antigen/metabolism , Immune Checkpoint Proteins/metabolism , Leukemia, Lymphocytic, Chronic, B-Cell/metabolism , Receptors, Immunologic/metabolism , Adult , Aged , Antigens, CD/metabolism , Antigens, Differentiation, T-Lymphocyte/metabolism , B-Lymphocytes/metabolism , Cell Proliferation/physiology , Cells, Cultured , Female , Humans , Lectins, C-Type/metabolism , Leukocytes, Mononuclear/metabolism , Lymphocyte Activation/physiology , Male , Middle Aged , RNA, Messenger/metabolism , T-Lymphocytes/immunology , Up-Regulation/physiologyABSTRACT
The impairment of immunological surveillance caused by aberrant T cell activation can lead to an inadequate anti-tumor response. Therefore, deregulation in co-stimulatory pathway might be associated with cancer susceptibility. Here we undertook a prospective study to investigate whether genetic variations in gene encoding molecule CD28 and CTLA-4 playing pivotal role in regulating adoptive immune response can influence susceptibility to prostate cancer. Single nucleotide polymorphisms (SNPs) in CTLA-4 and CD28 genes were genotyped in 301 prostate cancer (PCa) patients and 301 controls. The distributions of the genotypes and haplotypes in the CTLA-4/CD28 SNPs were similar in both studied groups. However, the overrepresentation of carriers of CTLA-4c.49A>G[A] allele and carriers of CTLA-4g.319C>T[T] allele in PCa as compared to controls was observed (p = 0.082 and p = 0.13, respectively). The risk of disease was higher (OR 1.78) for carriers of both susceptibility alleles as compared to carriers of protective genotypes (p = 0.03). The CTLA-4c.49A>G and CTLA-4g.319C>T SNPs might be considered as low risk susceptibility locus for PCa.
Subject(s)
CD28 Antigens/genetics , CTLA-4 Antigen/genetics , Genetic Predisposition to Disease/genetics , Prostatic Neoplasms/genetics , Prostatic Neoplasms/immunology , Genotype , Humans , Male , Middle Aged , Polymorphism, Single Nucleotide , Risk FactorsABSTRACT
Abnormal expression of the costimulatory molecules cytotoxic T-lymphocyte antigen 4 (CTLA-4), CD28, and inducible co-stimulator (ICOS) leads to disturbances of immune response and an increased risk of cancer. An extended study was undertaken to evaluate the association among the polymorphisms CTLA-4c.49A>G, CTLA-4g.319C>T, CTLA-4g.*642AT(8_33), CD28c.17+3T>C, and ICOSc.1554+4GT(8_15) and susceptibility to B-cell chronic lymphocytic leukemia (B-CLL) in the Polish population. The study revealed increased frequency of the CTLA-4g.319C>T [T] allele and the CTLA-4g.319C>T [T] phenotype in B-CLL patients compared with healthy controls (p = 0.003, odds ratio [OR] = 1.73; and p = 0.009, OR = 1.74, respectively). The presence of the CD28c.17+3T>C [C] allele and the CD28c.17+3T>C [C] phenotype increased the OR of B-CLL to 1.59 (p = 0.007) and 1.74 (p = 0.007), respectively. Either CTLA-4g.319C>T or CD28c.17+3T>C was associated with time to Rai stage progression. The distributions of the alleles and genotypes of the ICOS gene significantly differed between patients and controls (p = 0.0009 and p = 0.006, respectively). Individuals possessing short alleles were 2.02 times more prone to B-CLL than others (p = 0.001), whereas carriers of long alleles were protected from B-CLL (p = 0.02, OR = 0.62). The haplotype association study and multivariate analysis confirmed the association of CTLA-4g.319C>T and ICOSc.1554+4GT(8_15) gene polymorphisms with B-CLL. The polymorphic sites CTLA-4c.49A>G and CTLA-4g.*642AT(8_33) did not correlate with B-CLL. Our results are the first in the literature to report that gene polymorphism of the costimulatory molecules CTLA-4, CD28, and ICOS contributes to susceptibility to B-CLL.
