Distribution of the HLA class II frequency alleles in patients with leprosy from the mid-west of Brazil

In an attempt to clarify the issue of genetic predisposition to leprosy, we examined the distribution of class II human leucocyte antigen variants (DR and DQ) in 70 patients from around the city of Goiania, Brazil. Only two of the patients presented the tuberculoid form of the disease, whereas 17 fell into the lepromatous category; 51 were intermediate. The allele frequencies found were compared with those in a group of 77 healthy controls. We found an increased frequency of the HLA-DRB1*11 allele in patients with lepromatous leprosy compared with healthy controls (P=0.0132; RR=4.130, 95% Cl: 1.338 to 12.747). These results suggest that the DRB1*11 allele could be related with susceptibility to lepromatous leprosy in Brazil.     

Do human leukocyte antigens have a role to play in differential manifestation of multibacillary leprosy: A study on multibacillary leprosy patients from North India

118 multibacillary leprosy patients with differential manifestations were studied for the antigens they expressed at MHC loci to investigate the role of human leukocyte antigens in the differential response to the same causative agent. While the lepromatous leprosy (LL) patients showed a significant increase of Bw60, DR2, DRw8 and DQw1, borderline lepromatous (BL) patients had Bw52, DR9 and DQw7 significantly more often as compared to the normal controls. A comparison of LL, BL and mid-borderline (BB) patients showed a significantly higher frequency of Bw60 in LL patients as compared to the BL. However, Bw52, Bw53, DR9 and DQw7 were found significantly more often in the BL patients as compared to the LL patients but the difference failed to reach significance after pc. A comparison of HLA antigens in BB patients with those of either the LL or BL patients did not show any significant differences.     

Endogenous retroviral long terminal repeats of the HLA-DQ region are associated with susceptibility to insulin-dependent diabetes mellitus

HLA-DQ genes are the main inherited factors predisposing to IDDM. This gene region harbors long terminal repeat (DQ LTR) elements of the human endogenous retrovirus HERV-K, which we analyzed for a possible association with disease. We first investigated whether LTR segregate with DQ alleles in families. Members (n = 110) of 29 families with at least one diabetic child, unrelated patients with IDDM (n = 159), and healthy controls (n = 173) were analyzed. Genomic DNA was amplified for DQ LTR3 by a nested primer approach as well as for DQA1 and DQB1 second exons, to assign DQA1 and DQB1 alleles. DQ LTR segregated in 24 families along with DQ alleles. Of the 29 families, 20 index patients were positive for DQ LTR. The DQ LTR was in all patients on the haplotype carrying the DQA1 ^*0301 and DQB1 ^*0302 alleles. A majority of patients had DQ LTR (62%) compared with controls (38%) (p < 1.3 × 10^{− 5}), even after matching for the high-risk alleles DQA1 ^*0501, DQB1 ^*0201-DQA1 ^*0301, and DQB1 ^*0302 (79% of patients and 48% of controls; p < 0.02). Subtyping for DRB1 ^*04 alleles in all DQB1 ^*0302 ⁺ individuals showed 56% DRB1 ^*0401, DQB1 ^*0302 [LTR⁺ patients vs. 29% controls with the same haplotype (p < 0.002). In conclusion, these data demonstrate the segregation of DQ LTR with DQA1, DQB1 alleles on HLA haplotypes. Furthermore their presence on DRB1 ^*0401-, DQA1 ^*0301-, and DQB1 ^*0302-positive haplotypes suggest that they contribute to DQ-related susceptibility for IDDM. Human Immunology 50, 103–110 (1996)     

Analysis of HLA-DM polymorphisms in sarcoidosis

Sarcoidosis is a multisystemic granulomatous disorder showing significant increases in the HLADRB1 ^*11, ^*12, ^*14 and ^*08 alleles in the Japanese population. To evaluate the role of polymorphism in the DMA and DMB genes in predisposition to sarcoidosis, seventy Japanese patients with sarcoidosis and 95 unrelated healthy controls were analyzed in the third exon polymorphisms within the DMA and DMB genes by the PCR-RFLP method. There were no differences in the distribution of DMA alleles between the patient and control groups. The frequency of DMB^*0102 was higher (p < 0.05) and that of DMB^*0101 was lower (p < 0.05) in the patients than in the healthy controls. However, this association and negative association could be explained by linkage disequilibrium with the disease-associated DRB1 alleles. The DMA and DMB genes do not primarily confer the susceptibility to sarcoidosis.     

HLA-encoded susceptibility to insulin-dependent diabetes mellitus is determined by DR and DQ genes as well as their linkage disequilibria in a Chinese population

HLA-DRB1 and -DQB1 genes were analyzed in 98 Chinese IDDM patients and 205 control subjects from Taiwan. The DRB1^*0301-DQB1^*0201 haplotype conferred strong susceptibility (RR = 7.7, p_c < 10−5). DRB1^*0405 also conferred susceptibility (RR = 3.1, p_c < 0.0005) whereas DRB1^*0403 (RR = 0.7) and DRB1^*0406 (RR = 0.2) conferred protection. Indeed, the relative risk for the DRB1^*0405-DQB1^*0302 haplotype (RR = 33.7, p_c < 0.002) was 48 and 168 times higher than those conferred by the DRB1^*0403-DQB1^*0302 and DRB1^*0406-DQB1^*0302 haplotypes, respectively, suggesting that the protection conferred by DRB1^*0403 and 0406 is dominant over DQB1^*0302. The strong linkage disequilibrium observed between DQB1^*0302 and DRB1^*0403(0406) can thus explain the surprising finding that the frequency of DQB1^*0302 was not significantly increased in the Chinese IDDM patients (RR = 0.9). Because the DRB1^*0405-DQB1^*0302 haplotype (RR = 33.7) conferred higher susceptibility than the DRB1^*0405-DQB1^*0401 (RR = 2.5) or DRB1^*0405-DQB1^*0301 (RR = 2.1) haplotypes, DQB 1^*0302 is indeed a susceptibility factor, while both DQB1^*0301 and DQB1^*0401 may confer protection against IDDM. The increased frequency of the protective DQB1^*0401 allele in patients compared to controls is due to linkage disequilibrium between DRB1^*0405 and DQB1^*0401. Interestingly, the previously demonstrated protective effect of DQB1^*0602 was not very strong in the Chinese (RR = 0.4). Our results suggested that HLA-encoded susceptibility to IDDM is determined by the combined effects of all DR and DQ molecules present in an individual. Therefore, the genotypic combinations of DR and DQ genes as well as their linkage disequilibria can influence IDDM susceptibility. At least four DR and DQ molecules conferring high susceptibility (DRB1^*0301, DRB1^*0405, and DQ/β0301/0201 and 0301/0302) occur at high frequency in the Chinese population. However, linkage disequilibria between highly susceptible DR and protective DQ or vice versa (e.g., DRB1^*0405-DQB1^*0301(0401] and DRB1^*0403[0406]-DQB1^*0302) are probably responsible for the lower incidence of IDDM in the Chinese.     

Transporter associated with antigen-processing (TAP) genes and susceptibility to tuberculoid leprosy and pulmonary tuberculosis

We have studied TAP polymorphism in a panel of 40 healthy individuals, 57 patients with pulmonary tuberculosis (PTB) and 50 with tuberculoid (TT) leprosy from North India. Only TAP2-A/F occurred with a significantly increased frequency in PTB patients as compared to controls (82.5% vs. 52.5%, P<0.002, Pc<0.01) giving a high relative risk of 4.3. On the other hand, TAP2-B was significantly increased in TT leprosy as compared to controls (76% vs. 47.5%, Pc<0.003, RR 3.5) particularly in patients positive for HLA-DR15 than controls carrying DR15 (77.5% vs. 50%, P<0.03, RR=3.4). Further, TAP2-B allele was positively associated with DR15 negative PTB patients as compared to the DR15 positive group (43.8% vs. 17.1%, P<0.04, RR=0.3), This study along with our earlier studies on HLA association in mycobacterial diseases suggests that in addition to HLA-DR15, alleles in the TAP2 region influence susceptibility to PTB and TT leprosy.     

Association of responsiveness to the major pollen allergen of Parietaria officinalis with HLA-DRB1 alleles a multicenter study

Parietaria, a plant belonging to the family of Urticaceae, is a major source of allergenic pollen in Europe. In the context of a multinational study, we investigated whether in allergic subjects antibody response towards Par o l, the major allergen from P. officinalis, was associated with defined HLA-DRB1^* alleles.

The study population consisted of 234 allergic patients: 65 from Bulgaria, 30 from Israel, 99 from Italy, and 40 from Spain.

In the Italian study group, the prevalence of ST positivity to Parietaria was 77%. In Parietaria ST-positive subjects, the prevalences of IgG and IgE serum Ab towards Par o 1 were 91% and 75%, respectively. HLADRB1*1101 and/or 1104 were significantly positively associated with the presence of IgG Ab and with high levels of IgE Ab towards this allergen (p = 0.0007) and p = 0.012, respectively).

In the Spanish study group, the positive association of DR 1100 with responsiveness to Par o 1 was confirmed (p = 0.02, RR = 4, and p = 0.002, RR = 7, for IgG and IgE Ab, respectively). None of the Bulgarian patients had IgE Ab to Par o 1, whereas IgG Ab response was observed in 7 out of 65 subjects and was positively associated with DRB 1^*1101 and/or 1104 (p = 0.025). In the Israeli study group, responsiveness to Par o 1 was not associated with specific HLA-DRB1^* alleles.

In conclusion, this study shows that in allergic patients from three European populations antibody response to the major allergen from the pollen of Parietaria is associated with HLA-DRB1^* 1101 and/or 1104. Our data suggest that this association is stronger in subjects monosensitized to Parietaria.     

Association between killer-cell immunoglobulin-like receptor genotypes and leprosy in Brazil

The aim of this study was to investigate the role of killer cell immunoglobulin-like receptor (KIR) genes in leprosy immunopathogenesis. Genotyping of KIR and human leukocyte antigen (HLA) genes was performed by polymerase chain reaction with sequence-specific oligonucleotide probes in 165 leprosy patients. Both activating KIR2DS2 and KIR2DS3 frequencies were higher in tuberculoid leprosy (TT) patients than in lepromatous leprosy (LL) patients, and the inhibitory KIR with its ligand, KIR2DL1-C2/C2, was elevated in TT patients in comparison to all other leprosy subgroups and controls. However, a negative association between KIR2DL3-C1 and KIR2DL3-C1/C1 and the TT group was identified. Borderline patients exhibited a higher frequency of KIR3DL2-A3/11 than the controls and LL patients, and a lower frequency of KIR2DL1-C2 than the controls and TT subgroup. Some KIR-HLA genotypes could be associated to the development of clinical forms of leprosy and should be investigated further.     

Evaluation of cell mediated immune responses in untreated cases of leprosy

Twenty-three leprosy patients have been studied in an endemic area before institution of chemotherapy. These were comprised of ten lepromatous leprosy, four borderline lepromatous and nine tuberculoid leprosy cases on basis of clinical features, bacteriological and marphological indices. Histopathology of skin biopsies classified two as truly polar lepromatous leprosy (LL) and three as polar tuberculoid (TT), while the remaining eighteen were at various stages of evolution towards lepromatous or tuberculoid end of the spectrum. All lepromatous and borderline leprosy patients showed negative delayed hypersensitivity reaction with lepromin, but six out of fourteen patients in this category gave positive reaction with PPD. Blast transformation with PHA of peripheral leucocytes from all cases of lepromatous leprosy cultured in standard AB serum was depressed in comparison with cells from normal controls. ³H-thymidine incorporation in DNA of leucocytes in presence of leprolin was lower in cells of lepromatous leprosy group as compared to those from tuberculoid and borderline cases. There was lack of production of macrophage aggregation factor in all except one case of lepromatous leprosy while the test for this factor was positive for most of the tuberculoid leprosy patients. The homing characteristics of lymphocytes tagged with ⁵¹Chromium into liver and spleen of test mice were altered from the normal pattern in a large number of leprosy cases.     

Amyloid-related serum component (protein ASC) IN LEPROSY PATIENTS.

The presence of amyloid-related serum component, protein ASC, in serum samples from 63 leprosy patients was investigated. Protein ASC was detected in 38% of the patients. A correlation to the disease spectrum of leprosy was apparent: polar lepromatous cases, 64% positive; borderline lepromatous, 50%; borderline tuberculoid, 36%; subpolar tuberculoid, 17%; and polar tuberculoid, negative. Antibody activity against the a antigen of Mycobacterium leprae was also determined, showing a similar correlation to the disease spectrum. Serum samples from 23 apparently healthy Ethiopians serving as controls showed a protein ASC incidence of 22%. This figure is significantly higher than the frequency found by others among healthy Norwegian blood donors. Immunoglobulin M levels among patients were elevated in the borderline lepromatous and poplar lepromatous groups. The three tuberculoid groups did not differ in this respect from the control group but were all elevated as compared to a normal Caucasian serum pool. Although raised immunoglobulin M levels seemed to parallel increased frequencies of protein ASC in the patient groups as well as in controls, this correlation might be only secondary to a primary derangement in T-cell function.     

Association of C4B deficiency (C4B*Q0) with erythema nodosum in leprosy

A considerable number of studies have postulated significant associations between susceptibility to the different clinical manifestations of leprosy and the MHC, In this investigation, the association between the MHC class III complement proieins C2, BF, C4A and C4B and leprosy in a patient population of Southern Brazil was studied. A total of 109 non-related leprosy patients was investigated; 73 presented wilh lepromatous leprosy (LL), 46 of Ihem had the immunopathological reaction of erythema nodosum (ENL), the remaining 36 were tuberculoid, borderline and indeterminate leprosy (TIBL) patients. The control group included 172 healthy individuals matched with the patients according lo their ethnic and geographical origin, C2, BF, C4A and C4B allotypes were determined by slandard technologies including Western blots for C2 and C4 variant alleles wilh monoclonal and polyclonal antibodies. Non-expressed (‘silent’) C4 alleles in hemizygously deficient individuals were estimated semiquantitatively on the basis of the C4A and C4B isolype ratio and by the M ASC (‘minimal chi-square’) method. The results showed a significantly elevated presence of the non-expressed C4B allele (C4B*Q0) in the LL and ENL patient groups in comparison with the controls. The most signifieant difference was observed in the ENL group when compared with the controls. In addition, all patients who were homozygously C4B-deficient had ENL, and most of them had the BF*F1 allele. The comparison between LL patients with and without ENL also showed a statistically significant difference in the presence of C4B*Q0, indieating thai C4B deficiency itself is associated with EN L. The relative risk of LL patients with the C4B*Q0 allele suffering from ENL was 53 compared with LL palients without C4B*Q0, Since immune complexes (IC) are considered to be the palhogenic cause of ENL, our findings indicate thai C4B deficieney may play an important role in the abnormal immune response against Myeobaeterium leprae and in the lack of IC clearance, leading to ENL reactions. Individuals wilh this allele seem to be at a higher risk of developing pathologieal immune reactivity in lepromatous leprosy.     

Pemphigus Vulgaris Autoantibody Response is Linked to HLA-DQB10503 in Pakistani Patients

ABSTRACT: Pemphigus vulgaris (PV) is an autoimmune disease of the skin and mucous membranes characterized by an autoantibody response against an epidermal cadherin. We performed high resolution HLA class II typing in 19 patients with PV from Rawalpindi, Pakistan and 19 non-Jewish European PV patients from Boston by sequence-specific oligonucleotide probe hybridization. The results were compared with two separate ethnically matched control populations. We found that PV patients from Pakistan had significantly increased frequencies of DRB1*1404 ( p = 0.01), DQA1*0101 ( p = 0.02), and DQB1*0503 ( p = 0.01). Among the patients of non-Jewish European ancestry, DRB1*1401 ( p < 10⁻⁶), DQA1*0101 ( p < 10⁻⁵) and DQB1*0503 ( p < 10⁻⁶), were increased in PV patients. Formal linkage analysis between the major histocompatibility complex and the PV antibody was performed in 67 relatives of the 19 Pakistani patients. The results showed strong evidence for linkage of HLA-DRB1*1404, DQA1*0101, DQB1*0503, with the presence of PV antibody in relatives’ families with a significant logarithm of the odds score of 6.06. Based on the three dimensional structure of class II molecules, we propose that HLA-DQA1*0101 and DQB1*0503, encode a negatively charged P9 peptide binding pocket of the DQ molecule and are significantly associated with susceptibility to PV in non-Jewish populations.     

Potential influence of interleukin-1 haplotype IL-1 beta-511*T-IL-1RN*1 in conferring low risk to middle third location of esophageal cancer: a case-control study

Interleukin (IL)-1 gene polymorphisms affect several inflammatory diseases, including cancer. Therefore, we studied genetic association of biallelic (-511C>T) polymorphism of IL-1β and 86-bp VNTR polymorphism of IL-1RN in 159 patients with esophageal cancer (EC) and 194 age- and gender-matched healthy controls. Genetic analysis for IL-1 polymorphisms was performed by polymerase chain reaction-restriction fragment length polymorphism. The frequencies of IL-1β (-511C>T) and IL-1RN (variable number tandem repeat) genotypes, alleles, and haplotypes did not differ significantly between patients and controls. However, IL-1β -511TT genotype and T1+ haplotype combination illustrated low risk for disease at the middle third location of the tumor (odds ratio [OR] = 0.27; 95% confidence interval [CI] = 0.11–0.62; p = 0.002; OR = 0.462; 95% CI = 0.253–0.845, p = 0.01). In conclusion, subjects with IL-1β -511TT genotype or IL-1β*T-IL-1RN*1 (T1) haplotype had lower risk for middle third tumor location of EC in a northern Indian population.     

Consequences of Smallpox Vaccination in Leprosy Patients

This study illustrates the consequences of smallpox revaccination in 45 lepromatous, 28 tuberculoid, and 47 normal individuals. Results obtained with intradermal inoculations indicated that the patients with leprosy were associated with a relative anergy against the vaccinia virus, the anergy being minimal in the tuberculoid leprosy but marked in the cases with lepromatous leprosy. Major vaccinial reactions were observed more often in patients with lepromatous leprosy than in the controls or patients with tuberculoid leprosy. Furthermore in a patient with lepromatous leprosy, vaccinia necrosum also developed. The smallpox vaccination with live virus also appeared as a provocative factor for the precipitation of lepra reaction in the lepromatous leprosy cases. After 3 weeks of vaccination, the frequency of the specific humoral antibody response was the same in the tuberculoid patients and controls while it was higher in the cases with lepromatous leprosy. The prevaccination titer of total hemagglutination inhibition antibody was significantly higher in the lepromatous leprosy cases. However, the postvaccinial, humoral antibody response of the lepromatous patients was of the same magnitude as that observed in the normal individuals, and it was mainly due to a 2-mercaptoethanol-resistant antibody.     

Association of MICA polymorphism with rheumatoid arthritis patients in Koreans

To investigate whether genetic variations of MICA are associated with susceptibility to rheumatoid arthritis (RA), the (GCT)n microsatellite polymorphism of the transmembrane domain was analyzed in 144 Korean patients with RA and in 297 unrelated healthy controls. The allele frequency of MICA*A9 significantly decreased in RA patients compared with controls (9.0% vs. 15.3%, odds ratio [OR] = 0.55, p = 0.0098, p_c = 0.049), whereas the frequency of the MICA*A4 and MICA*A5.1 alleles tended to increase in RA patients (21.2% vs. 14.8%, OR = 1.55, p = 0.018, p_c > 0.05; 20.5% vs. 15.0%, OR = 1.46, p = 0.0403, p_c > 0.05). By subgroup analysis, the MICA*A4 allele significantly increased in seropositive RA patients versus controls (23.0% vs. 14.8%, OR = 1.69, p = 0.0082, p_c = 0.041). HLA-DRB1*0405 was strongly associated with RA (p_c = 0.0000008), and strong linkage disequilibrium was observed between HLA-DRB1*0405 and MICA*A4 alleles in controls (p_c = 0.000004) as well as in RA patients (p_c = 0.0012). In Korean patients, HLA-DRB1*0405 was primarily associated with RA and the weak association of RA with MICA*A4 was secondary to that with HLA-DRB1*0405. Additionally, MICA*A9 might have a weak protective effect on the susceptibility to RA in Koreans.     

Lymphocytotoxins in leprosy and in asymptomatic hepatitis B virus infection.

Serum lymphocytotoxic antibodies (LCAs) were detected in 67% of Papua New Guinean lepromatous leprosy patients who were persistent carriers of hepatitis B surface antigen (HBsAg). Lymphocytotoxins were not associated with asymptomatic HBsAg in either healthy controls or tuberculoid leprosy patients. It was apparent that, although HBsAg itself is a poor indicator of in vitro lymphocytotoxicity, when the antigen occurred in a host with impaired immune response, lymphocytotoxicity, when the antigen occurred in a host with impaired immune response, lymphocytotoxicity was enhanced. In contrast to this finding, lepromatous leprosy patients without HBsAg had significantly depressed LCA production in comparison with tuberculoid patients and controls. The interaction between leprosy and hepatitis B virus was highly significant (P = 0.001) in an analysis of variance of cytotoxicity scores. It is proposed that the previously reported equivocal results regarding autoantibodies in leprosy patients may be explained by this unusual interaction between lepromatous leprosy and hepatitis B virus infection.     

Genetic polymorphisms of the major histocompatibility complex-encoded antigen-processing genes TAP and LMP in sarcoidosis

Sarcoidosis is a granulomatous disease showing a significant increase in the HLA-DR5, -DR6, and -DR8 associated alleles in Japanese. To investigate whether the class I antigen-processing genes, encoded within the MHC class II region between the HLA-DP and -DQ loci, are involved in determining the susceptibility to Sarcoidosis, TAP1, TAP2, and LMP2 alleles were analyzed by the PCR-RFLP method in 85 Japanese patients with Sarcoidosis and 91 healthy controls.

There were no significant differences in the distribution of TAP1 and LMP2 alleles between the subgroups of the patients and controls positive or negative for DR5, DR6, and DR8. A significant decrease in the frequency of TAP2*0201 was found among the patients negative for DR5, DR6, and DR8 as compared to the DR-matched controls (p < 0.05), but this could be explained by its linkage disequilibrium to the negatively associated allele DR1. These findings suggest that the TAP or LMP2 gene is not primarily involved in the susceptibility to Sarcoidosis. In the course of this study, a linkage disequilibrium was observed in the Japanese population between TAP1 and TAP2 alleles, TAP1*0201 and TAP2*0102.     

HL-A Antigens and Susceptibility to Diseases. II. Leprosy

Thirty-nine leprosy patients (20 tuberculoid and 19 lepromatous) have been HL–A typed and compared to 36 non-leprosy individuals of the same ethnic group (Amharas). The most significant deviation was related to the W21 antigen, which was found only among leprosy patients (both tuberculoid and lepromatous), not in the control group. No deviation in antigen frequency was found to be specific to the lepromatous group.     

HLA Alleles are Genetic Markers for Susceptibility and Resistance towards Leprosy in a Mexican Mestizo Population

Despite the use of multidrug therapy, leprosy remains endemic in some countries. The association of several human leucocyte antigen (HLA) alleles and gene polymorphisms with leprosy has been demonstrated in many populations, but the major immune contributors associated to the spectrum of leprosy have not been defined yet. In this study, genotyping of HLA‐A, ‐B, ‐DR, and ‐DQ alleles was performed in leprosy patients (n = 113) and control subjects (n = 117) from the region with the highest incidence for the disease in México. The odds of developing leprosy and lepromatous subtype were 2.12‐ and 2.74‐fold higher in carriers of HLA‐A*28, and 2.48‐ and 4.14‐fold higher for leprosy and dimorphic subtype in carriers of DQB1*06. Interestingly, DQB1*07 was overrepresented in healthy individuals, compared to patients with leprosy (OR = 0.08) and the lepromatous subtype (OR = 0.06). These results suggest that HLA‐A*28 is a marker for predisposition to leprosy and the lepromatous subtype and DQB1*06 to leprosy and the dimorphic subtype, while DQB1*07 might be a resistance marker in this Mestizo population.     

Association studies of CTLA-4, CD28, and ICOS gene polymorphisms with B-cell chronic lymphocytic leukemia in the Polish population

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.