Possible association between HLA antigens and the response to interferon in Japanese patients with chronic hepatitis C

Correlation between the major histocompatibility complex class I antigens (HLA-A, -B and -C) and the elimination from serum of hepatitis C virus in patients with chronic hepatitis C has not been understood. We analyzed HLA phenotypes and their relationship to the efficacy of interferon treatment. Of the 172 patients who were treated with 9 million units of interferon-α2a three times a week for 6 months, 54 patients were responders and 118 patients were non-responders. No significant difference was observed between the 172 patients and 199 healthy subjects with regard to the frequencies of HLA-A, -B and -C antigen phenotypes. However, HLA-B55, B62, CW3 and CW4 frequencies were significantly higher in responders than in non-responders to the interferon treatment. CW4 was found to link with B62, but other phenotypes were independent each other. Patients with HLA B55, B62 and CW3 had a significantly lower viral load, and showed a better response to interferon. These results suggest that HLA system does not have an influence on the evolution towards chronicity of the disease due to hepatitis C virus, but HLA B55, B62 or CW4, and CW3 may be a virus quantity-regulating factors which then affect to response to the interferon treatment, indicating that these HLA antigens in conjunction with a viral peptide is a key target antigen for cytotoxic T lymphocytes in patients with chronic hepatitis C.     

Influence of HLA alleles in response to treatment with pegylated interferon-alpha and ribavirin in patients with chronic hepatitis C

The objective of this study was to analyse the possible role of HLA polymorphism of chronically infected hepatitis C virus patients in the response outcome to treatment with pegylated interferon-alpha plus ribavirin. To that end, 144 Brazilian patients infected only with genotype 1 of the virus were treated with pegylated interferon-alpha at 1.5 μg kg(-1) in conjunction with ribavirin (1000 mg if patient weight was <75 kg and 1250 mg if >75 kg) for 48 weeks. The patients did not have concomitant HBV or HIV infections or liver disease, did not undergo previous antiviral treatment, and were followed up for 24 weeks after the end of treatment to assure they presented a sustained virological response. Patients were classified according to response to treatment in responsive (SVR), nonresponsive (NRS) and relapsers (REL). HLA class I and class II typing were carried out through PCR-SSO using Luminex technology. A statistically higher frequency of DRB1*11 patients was observed in the SVR group (39.6% vs. 14.3%P = 0.0012; Pc = 0.0156; OR = 3.94; 95% CI = 1.8-8.8). HLA-DQB1*03 patients were also more frequent in the SVR group, but the P value lost significance after Bonferroni correction (62.3% vs. 41.7%P = 0.024; Pc = 0.14, OR = 2.3; 95% CI = 1.14-4.60). HLA class II antigens can positively influence the response to treatment with pegylated interferon-alpha and ribavirin.     

慢性丙型肝炎患者丙型肝炎病毒NS5A区序列与干扰素疗效的关系

目的　探讨上海地区丙型肝炎病毒 (HCV) 1b亚型慢性感染者的血清HCV非结构基因5A(NS5A)与干扰素 (IFN)疗效的关系。方法　收集上海地区 2 4例HCV1b慢性感染者在干扰素治疗前后及随访过程中的血清标本 ,定量检测治疗前血清HCVRNA ,用逆转录 聚合酶链反应方法扩增NS5A的干扰素敏感决定区 (ISDR)基因并进行测序和分析。另扩增干扰素应答类型不同的 3例患者治疗前后共 5株HCV病毒的NS5A全长序列 ,测序后作种系发生树分析及蛋白二级结构预测。结果　治疗前血清HCVRNA的定量结果显示 ,持续应答组的病毒滴度 (平均滴度 4 50× 1 0 4copies ml)明显低于复发组和无应答组 (平均滴度 1 82× 1 0 7copies ml)。 2 4例慢性丙型肝炎患者干扰素治疗前血清HCV的ISDR氨基酸序列与抗干扰素的HCV J株比较 ,1 3例为野生型 ,1 1例为中间型 ,无突变型。 6例完全应答者 3例感染的是野生型株 ,另 3例感染的是中间型病毒株。 5株HCV病毒的NS5A全长序列种系发生树显示 ,3种不同应答类型株在种系发生上分属 3个组别 ,无应答株与抗干扰素的HCV J株关系相近被归为 1组。蛋白质二级结构预测显示 ,上述病毒株NS5A蛋白在二级结构方面基本相似 ,仅在 2 2 55～ 2 2 89范围内有明显不同 ,这一区域与PKR结合域部分重叠。结论　HCVNS5A基因     

Genotypes and titers of hepatitis C virus for predicting response to interferon in patients with chronic hepatitis C

Interferon induces remission in about 50% of patients with chronic hepatitis C, but it is difficult to predict which patients will respond. Host and viral factors were evaluated for correlation with response to interferon in patients with chronic hepatitis C. Recombinant interferon alpha-2b with a total dose of 480-560 million units was given to 136 patients, of whom 74 (54%) responded. Genotypes of hepatitis C virus (HCV) in sera, I, II, III, IV, and V, were determined by poly-merase chain reaction (PCR) with type-specific primers. In 72 patients, pretreatment levels of HCV RNA were titrated by PCR in serial tenfold dilutions of RNA extracted from serum. Response to interferon occurred in 34 (40%) of 85 patients infected with HCV of genotype II, less frequently than in 22 (85%) of 26 with genotype III (P < 0.001) or in 7 (70%) of 10 with genotype IV. Of 51 patients with genotype II HCV, 6 of 8 (75%) with HCV RNA titers <10⁶ responded, more frequently than 4 of 43 (9%) with titers ≥ 10⁶ (P < 0.001). Responders were younger than non-responders (45.7 ± 11.7 vs. 50.3 ± 9.6 yr) and had received transfusions less frequently (26/74 or 35% vs. 37/62 or 60%, P < 0.01). Response to interferon correlated inversely with the severity of liver histopathology. These results indicate that response to interferon is influenced by HCV genotypes and pretreatment levels of HCV RNA in serum. © 1994 Wiley-Liss, Inc.     

丙型肝炎病毒血清型对慢性丙型肝炎干扰素抗病毒疗效影响的研究

目的研究丙型肝炎病毒血清型对慢性丙型肝炎于扰素抗病毒疗效的影响。方法对慢性丙型肝炎患者的血清进行ALT检测，采用Cobas amplicor monitor test，version 2．0（v2．0）试剂进行HCVRNA定量和Abbott公司的Murex HCV Serotyping 1-6 Assay试剂进行HCV血清学分型检测。对慢性丙型肝炎患者进行聚乙二醇于扰素a-2a（派罗欣）与罗荛愫（Roferon—A）治疗24周和24周随访结束的生化指标和病毒学应答进行观察，分析不同HCV血清型患者在抗病毒治疗后生化和病毒学应答的差异。结果98例患者共检出血清6型2例、5型1例、4型1例、3型10例、2型23例和1型44例，仍有17例未能分出血清型。派罗欣治疗组24周治疗结束时各血清型和未分型组之间的ALT复常率和病毒应答率无差异，而48周随访结束血清非1型的ALT复常率（76．2％）和持续病毒应答率（66．7％）高于血清1型，血清1型ALT复常率和持续病毒应答率分别为27.3％和27．3％，差异有统计学意义（P=0．035）。罗荛愫组末分型组、血清1型和非1型之间24周治疗结束时和随访结束时的ALT复常率和病毒学应答率均无差异。结论在6个月的IFN抗病毒疗程时，HCV血清型仅在派罗欣治疗组影响慢性丙型肝炎抗病毒治疗的持续病毒应答率。     

Efficacy of interferon treatment (IFN) in elderly patients with chronic hepatitis C

The aim of this study was to evaluate the efficacy and tolerability of interferon treatment in aged patients with chronic hepatitis C. One hundred and fifty-four patients with chronic hepatitis C, consecutively treated with a-interferon (a-IFN), were retrospectively subdivided into two groups according to age =60 or <60 years. The two groups were compared in terms of biochemical and histological activity of the disease, HCV genotype, total dose of IFN received, incidence of side effects and rate of response to treatment. Statistical analysis was performed by Student's t test, chi-square test and Fisher's exact test. Aged patients had a higher prevalence of HCV genotype 1b and cirrhosis and received a lower dose of the drug. No differences were found in other epidemiological-clinical characteristics before treatment. The rate of sustained response and long-term response to therapy was similar in the two groups of patients (18% and 8% in the aged and 20% and 13% in the younger respectively). There was a trend of more frequent major side effects in aged patients (p=0.07). Treatment of chronic hepatitis C with a-IFN had the same efficacy in the two groups observed. In aged patients with chronic hepatitis C treatment with the more effective pegylated IFN should be taken into consideration, especially when association with ribavirin is at high risk of adverse events.     

IgG1 anti-P2 as a marker of response to interferon in patients with chronic hepatitis C.

To study the relations of antibody production to long-term outcomes after interferon (IFN) treatment in patients with chronic hepatitis C (CH-C), we used ELISA to measure the levels of antibodies against HCV core protein and peptides. Samples from 21 complete responders and 36 non-responders were collected before IFN therapy, soon after the end of IFN therapy and 6 months later. Using a set of 19 synthesized HCV core peptide antigens, we found that anti-P2 (11-25a.a.) was the most prevalent of all IgG antibodies (93%: 39/42). Among complete responders, IgG1 anti-P2 levels had fallen by the end of IFN therapy (from 79.8 +/- 60.4-46.1 +/- 44.2: P < 0.01), and were lower still 6 months after the end of IFN therapy (31.0 +/- 35.2: P < 0.001); this change was the greatest of all antibodies studied. Among the non-responders, there was no change within the follow-up period. Soon after the end of IFN therapy, IgG1 anti-P2 levels were more than 30% lower than the initial value in more than two-thirds of the complete responders, but in only one-third of the non-responders (14/20 vs. 8/25: P < 0.05). Six months after the end of IFN therapy, IgG1 anti-P2 levels were more than 30% lower than the initial value in more than 85% of the complete responders, but in only 12% of the non-responders (17/20 vs. 3/25: P < 0.001). In conclusion, the changes in levels of IgG1 anti-P2 paralleled the activity of chronic hepatitis C after IFN therapy, and IgG1 anti-P2 levels may be markers of the efficacy of IFN therapy.     

Analysis of clinical and virological factors associated with response to alpha interferon therapy in chronic hepatitis C

Interferon alpha (IFN-α) therapy is currently the treatment of choice for chronic hepatitis C (HCV) infection, but it fails to achieve a sustained response in approximately 75% of those treated. The factors which determine whether or not an individual will respond to IFN-α are uncertain, although a number of potentially predictive factors have been proposed. In this study a wide range of clinical, demographic, and virological parameters were evaluated in relation to therapeutic outcome in a group of 30 Italian patients with chronic hepatitis C. All patients received 3 MU leukocyte-derived IFN-α three times a week for 6 months and were then followed prospectively for at least 12 months. 53% of patients responded initially, but a sustained response was observed in only 17%. Responders were found to be significantly younger than nonresponders (45.6 ± 3.1 vs. 55.4 ± 2.7), and less frequently cirrhotic (2/16 vs. 7/14). Sustained responders had a mean pretreatment HCV-RNA titer approximately tenfold lower than that of those who did not have a sustained response, but the difference was not statistically significant. HCV genotype was found to be significantly associated with both initial and sustained response. Patients infected with HCV-2a were more likely to respond (89%) than those who were infected with HCV-1 b (37%), and they were also more likely to sustain that response (33% vs. 6%). Geometric mean titers did not vary significantly between the different genotypes. © 1995 Wiley-Liss, Inc.     

Efficacy of long-term interferon therapy in chronic hepatitis B patients with HBV genotype C

Infection with Hepatitis B virus (HBV) genotype C predominates in Japan. We analyzed the efficacy of interferon (IFN) alpha or beta in the treatment of chronic hepatitis B patients with HBV genotype C and the clinical predictors for therapeutic response. Forty-three genotype C-infected, chronic hepatitis B e antigen (HBeAg)-positive patients (32 men and 11 women with a mean age of 35.6+/-10.1 years) who had been treated with IFN therapy were retrospectively studied. The patients were classified into two treatment groups. Short-term therapy group was administered a 5-6 MU dose three times weekly for 4 weeks, and the long-term therapy group for 24 weeks. At the end of the follow-up period, 4 (15%) of 27 short-term therapy group patients and 6 (38%) of 16 long-term therapy group patients had normalized serum ALT levels and seroconversion of HBeAg to anti-HBe (p=0.137). Multivariate analysis for parameters most important for the efficacy of IFN therapy was performed using Cox proportional hazard models in order to investigate the association between baseline characteristics of patients and the response to IFN treatment. As a result, the p-values of IFN treatment group and sex were <0.05, and both factors can be recognized as independent significant factors (relative risk, 2.93 and 2.53; p=0.027 and 0.040, respectively). Furthermore, the cumulative rates of seroconversion of HBeAg to anti-HBe analyzed by the Kaplan-Meier method was significantly higher in the female group (p=0.015) and in the long-term IFN therapy group (p=0.0046). In summary, long-term IFN therapy may be more effective than short-term IFN therapy for patients with chronic HBV genotype C infection.     

慢性丙型肝炎肝组织HCV特异性CTL活性对干扰素应答效果的影响

目的 了解肝组织丙型肝炎病毒（HCV）特异性细胞毒性T淋巴细胞（CTL）活性对慢性丙型肝炎患者干扰素治疗效果的影响。方法 用标准铬释放法对45例拟接受α干扰素治疗的慢性丙型肝炎（慢丙肝）患者肝组织CD8^ HCV特异性细胞毒性T淋巴细胞（HCV－CTL）活性进行检测,观察CTL活性与干扰素疗效的关系。结果 45例慢丙肝中20例（44．4％）肝组织HCV－CTL活性阳性。在完成干扰素治疗的42例中,19例HCV－CTL活性阳性。经过6个月的干扰素治疗,42例中共18例（42．9％）获得治疗终点完全应答15例（78．9％）为ETR,而23例HCV－CTL活性阴性患者仅3例（13．05）为ETR（P＜0．01）;10例持续应答者均为HCV－CTL活性阳性患者。结论 机体细胞免疫,尤其是CD8^ HCV-CTL介导的细胞免疫在决定慢性丙型肝炎干扰素治疗的效果中起重要作用。     

Association of HLA antigens with chronic active hepatitis (CAH) in children

HLA-A and -B antigen frequencies were investigated in a group of 46 children with chronic active hepatitis (CAH) and in a control group of 100 healthy children. The diseased group comprised 43 HBsAg positive and 3 HBsAg negative children. From the antigen frequencies relative risks (RR) were calculated according to the method of Woolf. The A1 and B8 antigens, known to be associated with autoimmune diseases, were only moderately more frequent in the CAH group than in the control. The relative risk for B8 antigen was 2.23 which is near to a significance level of p = 0.05. When the calculations were performed for 43 HBsAg positive CAH children the RR decreased to 1.70. Additionally, observations were performed on associations of HLA antigens with the occurrence of antinuclear antibodies (ANA) and anti-smooth muscle antibodies (SMA). Positive associations were found for ANA with B13 antigen (RR = 14.13) and for SMA with B5 antigen (RR = 13.66) with X2 4.85, and 5.51 respectively, at 1 degree of freedom. The p values, situated between 0.05 and 0.01 were insignificant after the correction for the number of antigens studied.     

Expression of interferon receptor genes in the liver as a predictor of interferon response in patients with chronic hepatitis C.

Interferon (IFN) receptor mRNA expression patterns in the liver have been shown to correlate with the effectiveness of IFN therapy in patients with hepatitis C virus (HCV) infection. However, it is not clear to what extent this factor contributes to the short (primary)- and long (sustained)-term results of IFN treatment with respect to biochemical and virological remission. Eighty-two patients who subsequently received lymphoblastoid IFN-alpha therapy underwent liver biopsies before IFN therapy. Possible factors that might correlate with IFN response were chosen and analyzed. The primary biochemical and virological responses at the end to treatment (24 weeks) were 63% and 43% vs. 46% and 32% for sustained biochemical and virological remission at the end of follow-up (48 weeks), respectively. In univariate analysis, the absence of HCV genotype 1b, a low titer of HCV RNA, and the expression of IFN receptor mRNA were significantly correlated with sustained biochemical and virological responses to IFN therapy. Multiple logistic regression analysis showed that IFN receptor mRNA expression and the absence of genotype 1b were significant predictors of the sustained biochemical and virological effectiveness of IFN therapy. IFN receptor mRNA expression predicted a sustained virological response to IFN therapy with a positive predictive value of 100% with genotype non-1b and had a negative predictive value of 97% with genotype 1b. It is concluded that expression of IFN receptor genes in the liver is a useful index for predicting the short- and long-term efficacy of IFN therapy in patients with chronic HCV infection.     

Dynamics of viral quasispecies during interferon therapy in non responder chronic hepatitis C patients.

BACKGROUND: the reference method to study the HCV complexity was cloning and sequence analysis of a sufficient number of clones. The evolution of the viral complexity in chronic non responder patients during treatment with standard doses of interferon was not very well investigate because this method was expensive and labour intensive when large series of patients were concerned. Meanwhile, with the alternative Single-Strand Conformation Polymorphism (SSCP) method, a rough estimation of the quasispecies present in a given sample could be obtained. OBJECTIVES: the aim of the study was to analyse the evolution of HCV heterogeneity, investigated by SSCP analysis targeted to the HVR-1, in 30 nonresponders chronic hepatitis C patients treated by Interferon-alpha 3MUI. RESULTS: genotype 1 was the main HCV type found in this population (77% of non responder patients). Before treatment, the SSCP assay revealed a high complexity pattern: the median of SSCP band number was 9. During IFN-alpha treatment, SSCP band number didn't change. However a significant decrease of the viral load was observed (P<0.01). Patients with variations in their SSCP patterns after therapy significantly decreased HCV RNA levels (P<0.002). In one third of patients the SSCP profile didn't change at all. CONCLUSIONS: we observed that viral heterogeneity didn't change in non responder chronic hepatitis C patients during IFN-alpha treatment. Nevertheless patients with a low number of pre-treatment quasispecies exhibited an improvement of the response (P<0.02). These phenomena were probably due to a selection of resistant variants present prior onset of therapy.     

Serum hepatitis C virus RNA level as a predictor of subsequent response to interferon-α therapy in Japanese patients with chronic hepatitis C

Serum hepatitis C virus (HCV) RNA level has been shown to be a good predictor of subsequent response to interferon-α (IFN) therapy in US patients in whom genotype 1a/1b are both predominant. To determine whether serum HCV RNA level is a predictor of subsequent response to IFN in Japanese patients or not, appropriately collected pre-IFN therapy serum samples from 35 Japanese patients with chronic HCV infection were studied. Serum HCV RNA level and HCV genotype were determined and correlated with the subsequent response to IFN. Response to IFN was defined by serum alanine transaminase level: complete and sustained response (n = 15), complete response followed by relapse (n = 10), and no response (n = 10). Patients with complete and sustained response had lower pre-IFN serum HCV RNA level (median: RT-PCR+, bDNA-) compared to the complete response to relapse group (median: 5.25 × 10⁶ genome equivalent/ml [eq/ml], P < 0.001) and the no response group (median: 10.63 × 10⁶ eq/ml, P < 0.001). Seven (46.7%) of the complete and sustained response patients had HCV genotype 2a and three patients had a mixture of genotypes 1b and 2a. In contrast, all 10 patients in the complete response to relapse group had genotype 1b whereas 8 of 10 patients in the non-response group had genotype 1b and 2 had genotype 2b. The patients with HCV genotype 2a had lower serum HCV RNA level than those with 1b (P = 0.002). When the HCV viremia were controlled by stratifying them into < and > 10⁶ eq/ml, patients with genotype 1 had a similar complete and sustained response rate compared to genotype 2. These data indicated that pre-IFN serum HCV RNA is also a good predictor of subsequent complete and sustained response in Japanese patients with chronic HCV infection. © 1994 Wiley-Liss, Inc.     

Isolated anti-HBc in chronic hepatitis C predicts a poor response to interferon treatment.

The sustained response to interferon-alpha treatment was evaluated in 147 anti-HCV/HCV-RNA-positive, HBsAg-negative, chronic hepatitis patients, according to HCV genotypes and the presence or absence of anti-HBs and anti-HBc. These patients had been included in a controlled study on the safety, tolerability, and efficacy of three types of interferon-alpha given at a dose of 3 MU three times weekly for 52 weeks. One hundred and two patients had HCV genotype 1, 42 a non-1 HCV genotype and 3 multiple HCV genotypes; 46 were anti-HBs and anti-HBc negative (group A), 50 anti-HBs and anti-HBc positive (group B), and 51 anti-HBs negative and anti-HBc positive ("isolated" anti-HBc, group C). Serum HBV-DNA was detected by polymerase chain reaction in 15 of the 51 (29.4%) patients in group C and in none of those in groups A or B. The Sustained Response rate was higher in patients with a non-1 HCV genotype than those with HCV genotype 1 (31% vs. 17.7%, P > 0.1). Fewer patients in group C showed a sustained response than in group A or group B (7.8% vs. 30.4%, P = 0.009 and 7.8% vs 28%, P = 0.017, respectively). Moreover, the sustained response rate was high in patients with a non-1 genotype, both in group A (42.8%) and in group B (42.8%), intermediate in patients with HCV genotype 1 (23.3% in group A and 22.2% in group B) and low in group C, irrespective of HCV genotype (8.3% for genotype 1 and 7.1% for other genotypes). The data indicate that patients with HCV chronic hepatitis and isolated anti-HBc show a poor response to IFN-alpha, irrespective of the HCV genotype.     

GB virus C (GBV-C) infection in patients with chronic hepatitis C. Influence on liver disease and on hepatitis virus behaviour: Effect of interferon alfa therapy

The aim of this study was to evaluate, in patients with chronic hepatitis C, 1) the prevalence and the epidemiological characteristics of GB virus C (GBV-C) infection, 2) the influence of GBV-C on hepatitis C virus (HCV) infection, 3) the pathogenicity of GBV-C in the absence of treatment and under interferon therapy, and 4) the effect of interferon alfa on GBV-C and HCV replications. One hundred fifteen patients with chronic hepatitis C were studied. Before treatment, they were tested for GBV-C RNA by PCR and GBV-C genotype was determined for positive samples. Pretreatment information was collected, including age, gender, source of HCV, estimated duration of HCV infection, alanine aminotransferase and gamma-glutamyl transpeptidase activities, cirrhosis and Knodell's score on liver biopsy, HCV genotype, HCV viral burden and anti-HCV core IgM antibodies. The genetic complexity of the hypervariable region 1 (HVR1) of HCV was studied by PCR-Single Strand Conformation Polymorphism. All patients were treated with 3 to 9 mega units of interferon alfa-2a three times per week for 3 to 6 months. The influence of GBV-C on the evolution of ALT and HCV replication during and after treatment was studied, and GBV-C and HCV RNA were monitored monthly by PCR during this period. Eighteen patients (16%) were GBV-C RNA-positive. Among 11 samples studied, GBV-C genotype 2a was present in 9 cases, 2b in one case and type 3 in one case. GBV-C RNA-positive patients were significantly younger than GBV-C RNA-negative ones (38.4 ± 11.5 vs. 47.4 ± 14.0, P = 0.012), a result independent of the route of transmission and the disease duration. No difference between GBV-C RNA-positive and -negative patients was found for other epidemiological parameters (e.g. gender, risk factor for parenteral viral infections, disease duration and HCV genotypes), or for the characteristics of HCV infection and related liver disease (e.g. HCV RNA level, genetic complexity of the HVR1, anti-HCV core IgM, alanine aminotransferase and gamma-glutamyl transpeptidase activities, cirrhosis and Knodell's score). GBV-C did not influence the rates of ALT normalization at months 3, 6 and 12 and of sustained hepatitis C virological response at month 12 of treatment follow-up. During treatment, GBV-C viremia became undetectable in 12 patients (67%) but relapse occurred after treatment withdrawal in all the nine patients with sufficient follow-up. In the remaining six patients (33%), GBV-C resisted interferon. Whatever the effect of interferon on GBV-C replication, the ALT levels correlated with the presence of HCV RNA. In conclusion, GBV-C infection is frequent in patients with chronic hepatitis C, who are mainly, but not exclusively, infected by GBV-C genotype 2a. GBV-C positive patients are significantly younger than GBV-C negative ones. GBV-C does not seem to affect HCV replication, liver disease and responses of HCV infection and liver disease to interferon therapy. GBV-C is sensitive to 3 mega units of interferon alfa administered three times per week in two-thirds of the patients, but relapse is constant with this dosage after treatment withdrawal. J. Med. Virol. 54:26–37, 1998. © 1998 Wiley-Liss, Inc.     

Association of chronic active hepatitis and HLA B35 in patients with hepatitis B virus

Fifty-one patients with chronic active hepatitis were typed for their HLA-A, B, C, and DR antigens. We observed a significant increase in the antigen frequency of HLA B35 in patients compared with controls.