ALBERT

Description: Abstract 4614 Introduction: There is strong evidence that altered immunological function entails an increased risk of B-cell chronic lymphocytic leukemia (B-CLL). The main mechanism of an antitumor response depends on T-cell activation. Unlike the constitutively expressed CD28, inducible costimulatory molecule (ICOS) is expressed on the T-cell surface after activation. ICOS enhances all the basic T-cell responses to a foreign antigen, namely proliferation, secretion of lymphokines, the up-regulation of molecules that mediate cell-cell interaction, and effective help for antibody secretion by B cells. ICOS is essential for both efficient interaction between T and B cells and normal antibody responses to T cell-dependent antigens. It does not up-regulate the production of interleukin-2, but superinduces the synthesis of interleukin-10. Our previous results indicated a role of ICOS gene as a susceptibility locus to B-CLL. Therefore an extended study was undertaken to evaluate the association between four ICOS polymorphisms (which were recently described as functional ones) and susceptibility to B-CLL in a Polish population. Methods: A case-control study of 296 individuals including 146 B-CLL patients was conducted on four polymorphisms in the ICOS gene. Genotyping of the polymorphisms ICOSISV1+173T〉C (rs10932029), ICOSc.1624C〉T (rs10932037), ICOSc.2373G〉C (rs4675379), and ICOSc.602A〉C (rs10183087) was done using allelic discrimination methods with the TaqManÒ SNP Genotyping Assay. Results: There were no statistically significant differences in the allele, genotype, and haplotype distributions between B-CLL patients and healthy controls for any of the investigated polymorphic markers in the ICOS gene. However, we noted that patients carrying genotype ISV1+173T〉C [TT], ICOSc.602A〉C [AA], ICOSc.1624C〉T [CC], and ICOSc.2373G〉C [GG] have a decreased frequency of progression to a higher Rai stage during 60-month follow-up (21.35 vs. 40.8%, p=0.013) compared with other individuals. Conclusion: This study showed that the investigated polymorphisms do not modulate the risk of B-CLL in the Polish population, but are associated with disease dynamics in particular with the time to Rai stage progression. Disclosures: No relevant conflicts of interest to declare.

Description: Abstract 4402 Introduction Dysfunction in cellular and humoral immunity entails an increased risk of B-cell chronic lymphocytic leukemia (B-CLL). It has been suggested that innate immunity, especially natural killers cells play key role in antitumor cytotoxicity regulated by interaction between killer immunoglobulin-like receptors (KIRs) on NK cells and some T-cell subpopulations and their HLA-class I ligands on target cells. KIRs receptors have been divided into two functional groups: with long cytoplasmic tails (DL) - inhibitory and with short cytoplasmic tails (DS) - activating. Two broad haplotypes of KIR genes have been defined: the A haplotype characterized by presence of single activating KIR gene (2DS4) and the B haloptype characterized by two or more activating KIR genes (2DS1, 2DS2, 2DS3, 2DS5 and 3DS1).The 2DL2, 2DL3 and 2DS2 KIRs bind to HLA-C1 allotype (Asp80), while 2DL1 and 2DS1 KIRs bind to HLA-C2 allotype (Lys80). Due to lack of representative data in literature the study was undertaken to determine the association between polymorphism of KIR genes and HLA-C allotypes and susceptibility to B-CLL. Patients and methods The following KIR genes were typed: 2DL1, 2DL2, 2DL3, 3DL1, 2DS1, 2DS2, 2DS3, 2DS4fl, 2DS4del, 2DS5, 3DS1, in 200 B-CLL patients and 199 healthy individuals using PCR-SSP method. The HLA-C1 and HLA-C2 were determined using Olerup SSP typing kit in 187 B-CLL patients and 104 controls. Results Individual KIR gene content was similar in B-CLL cases and healthy controls although patients with KIR2DS3 gene were more common among cases compared to controls (36% vs. 27%, p=0.06) (Table1). The frequency of AA haplotype did not differ between studied groups (29% vs. 28%). Moreover no differences were found between incidence of HLA-C allotypes (HLA-C1: 74.3% vs. 76.0%, HLA-C2: 67.4% vs.70.2%), genotypes (C1/C1: 32.6% vs 29.8%, C1/C2: 41.7% vs 46,2% and C2/C2: 25.7% vs 24.1) and KIR genes in combination with genes for their HLA-C ligands in B-CLL patients and controls (Table 2). Conclusions The data obtain in this study imply that there may be not direct association between KIR and HLA-C gene content in the genome and the presence of B-CLL. Disclosures: No relevant conflicts of interest to declare.