Properdin factor B and complement factor C4 allotypes in rheumatoid arthritis: results of a follow-up study.

The association between allotypes of properdin factor B (Bf), the fourth component of complement (C4A and C4B), and rheumatoid arthritis (RA), was investigated in a well-characterized cohort of RA patients who were followed from an early phase of the disease for a mean duration of 6 years. The frequencies of probable heterozygous C4AQ0 and of C4A3 were lower in RA patients compared to controls, irrespective of the presence of DR4 [relative risk (RR): 0.52 and 0.49, respectively, 95% confidence intervals (95% CI): 0.34-0.80 and 0.29-0.82]. The frequency of C4A4 was higher in RA patients compared to controls (RR: 1.86, 95% CI: 1.03-3.35), especially in DR4 positive RA patients compared to DR4 positive controls (RR: 2.58, 95% CI: 1.07-6.25), indicating a positive association of this allotype with RA additional to DR4. Bf and C4B allotypes were comparable in RA patients and controls. We did not find significant differences in Bf and C4 allotype frequencies in RA patients subdivided according to severity of the disease into a mild group and a progressive group. Because of inconsistent results in all studies on Bf and C4 allotypes, we conclude that C4 and Bf allotypes do not seem to have an important independent effect on determining disease susceptibility.     

贵州苗族补体Bf和C4B同种异型的多态性

用高压琼脂糖电泳后的免疫固定试验，检测了贵州苗族健康成人的补体旁路Ｂ因子（Ｂｆ）和Ｃ４Ｂ的同种异型。在检出的基因型中Ｂｆ有３个，Ｃ４Ｂ有１０个，最高基因频率的基因是Ｂｆ＊Ｓ０．９４４４。Ｃ４Ｂ＊２０．５０００．     

HLA, A, B, C, DR, C4, Bf in insulin-dependent diabetics in the Tunisian population

There is no doubt that the autoimmune process in human disease depends on genetic factors. Varying associations were noticed between HLA DR and autoimmune disorders. The frequency of HLA-A-B and DR antigens as well as the Bf and C4 allotypes have been investigated in insulinodependant diabetes mellitus (IDDM) and compared to that of healthy controls in Tunisian population. An increase of A30, DR3, DR4, BfF1, C4AQ0 and C4BQ0 and decrease of B40, DR2, DR5 and DR6 were found in diabetes when compared to the value observation controls. The strongest association was noticed with HLA, DR3 and DR4. The prospective role of DR2 and DR5 antigens were also confirmed. Examination of HLA, Bf and C4 alleles. Two supratypes associated with IDDM have been observed among the Tunisian patients.     

Complement C4A, C4B and BF haplotypes in Koreans

Specific alleles at C4A, C4B and BF loci occur in populations and are inherited in complotypes, which are linked with particular HLA haplotypes. Considerable differences in complement allele and complotype frequencies have been observed among various ethnic groups. In the present study, 109 Korean families were analyzed for complement and complotype polymorphism. Thirty-four different complotypes were detected: the most common was BF*S-C4A*3-C4B*1 (S31) with a frequency of 42.2%, followed by S42 (14.3%) and F31 (13.8%). Three complotypes, S42, F31, and FQ01, showed positive linkage disequilibrium. Some of the complotypes were linked with characteristic HLA haplotypes. Two complotypes carrying duplicated C4A genes, S3+31 (BF*S-C4A*3-C4A*3-C4B*1) and S3+2Q0(BF*S-C4A*3-C4A*2-C4B*Q0), were exclusively associated with HLA-A24-Cw7-B7-DR1-DQ1 and A24-CBL-B52-DR15-DQ1 haplotypes, respectively. Twelve families showed recombinant haplotypes, nine in the class I region, three between the HLA-B and HLA-DR loci, and none in the class III region. Maternal recombination occurred twice as frequently as paternal. The results obtained in this study represent the frequencies of complotypes and extended HLA haplotypes of well-defined Koreans, based on a family study.     

中国洛阳地区汉族人MHC补体单倍型的分析

应用国际补体参考实验室的方法，对洛阳地区正常汉族家系１８４条染色体做了补体单倍型的检测与分析，并与南方汉族做了比较，共发现频率大于０．０１的补体单倍型１９个，频率居前３位者为ＳＣ３１（０．２１７４）ＳＣ４２（０．１６８５）和ＳＣ３２（０．１０８７）有１１个型别呈连锁不平衡。Ｂｆ．Ｃ２，Ｃ４Ａ和Ｃ４Ｂ等位基因的频率分别以Ｂｆ．Ｓ，Ｃ２．Ｃ４Ａ３，Ｃ４Ａ４，Ｃ４Ｂ１和Ｃ４Ｂ２频率居高，而且洛阳汉族Ｂｆ     

C4 complement allotypes in juvenile dermatomyositis

Twenty probands with juvenile dermatomyositis and their relatives were studied to determine the inherited segregation patterns of class I, II, and III HLA region markers including C4A, C4B, Bf, and C2 complement polymorphisms. The extended haplotype B8, DR3, C4A*Q0, C4B*1, C2*C, and Bf*S was present in 13 of the 20 probands. Three other probands also carried a haplotype with a null allele for C4A and two further probands carried a null allele for C4B; only two probands had no detectable C4 null allele. These data confirm previous studies showing high frequencies of B8 and DR3 in patients with juvenile dermatomyositis, but show that there is a higher association with null alleles of C4. This suggests that the C4 genes are either themselves the disease-susceptibility genes or are in very strong linkage disequilibrium with such genes.     

HLA antigens and complotypes in insulin-dependent diabetes mellitus

One hundred and thirty-six Finnish patients with insulin-dependent (type I) diabetes mellitus were investigated for the HLA-A, B, D and DR antigens as well as the Bf and C4 allotypes. The statistically significant increase in the frequencies of HLA-A9, B8, B15, Dw3, Dw4, DR3, DR4, C4A0 and C4B3 was observed when compared with the healthy controls. About 79% of the patients had HLA-DR4, and 53% had HLA-DR3 antigens. A rare C4 allele C4B3 was found in 21% of the patients, whereas only in 2% among the controls (relative risk 16.35). The etiological fraction (EF) values indicated that HLA D/DR alleles were the best markers for IDDM, the observed EF for HLA-DR4 in diabetes was as high as 0.70. Examination of HLA, Bf and C4 phenotypes suggested that at least two supratypes "B15 BfS C4A3B3 D(R)4" and "B8 BfS C4A0B1 D(R)3" were markers for the susceptibility to type I diabetes, one third of our patients had either of these supratypes. The protective role of DR2 and Dw2 antigens was also confirmed: no HLA-Dw2 positive patients and only one with HLA-DR2 was found.     

Human MHC Class III (Bf, C2, C4) genes and GLO: their association with other HLA antigens and extended haplotypes in the Spanish population

C4 allotype frequencies and their combination with factor B and C2 alleles (complotypes) were studied in a sample of the Spanish population in relation to MHC class I, class II and GLO alleles. The shorter genetic distances found for C4 between Spaniards and North Africans and the high frequency of extended HLA haplotypes (GLO 2) HLA-DR3 F1C30 HLA-B18 HLA-Cw5 (HLA-A30) and HLA-DR7 S1C21 HLA-Bw50 HLA-Cw6 are consistent with a paleo-North African ethnic origin (about 20,000 years B.C.) of a part of present Spaniards (Iberians), and with the effect of racial admixture during late Moslem invasions (from the 8th to the 15th century). The complotype null alleles C4A QO and C4B QO may be under natural selection pressure when found in cis position, since they are never in the same haplotype in families. The underestimation of these C4 null alleles' frequencies in unrelated individuals as compared to genotyped families is shown to be a very likely event and a serious hindrance for C4-disease association studies. We have not found any C4 duplications in the Spanish population; this may be due to sample size limitations or to the degree of admixture of our population. Strikingly, no positive linkage disequilibrium between C4A and C4B alleles is detected in unrelated individuals nor in families, although strong associations are maintained among Bf, C2, C4, HLA-A, HLA-B, HLA-C and HLA-DR markers. Assuming that all MHC polymorphisms have reached equilibrium, several explanations are proposed, including the possibility of no, different or additional natural selection mechanisms operating on some MHC class III genes (Bf, C2, C4 alleles combinations for most appropriate C3 convertases), as compared to those affecting class I and class II gene clusters (most advantageous immune response genes sets).     

Studies of a C2 DNA polymorphism in RA, Felty's and normal subjects

A restriction fragment length polymorphism at the C2 locus was studied in rheumatoid arthritis (RA), Felty's and control subjects. No association was found between any C2 variant and either RA itself or within the rheumatoid population with Felty's syndrome. The C2 DNA polymorphism can be used to subdivide Bf*S- as well as Bf*F-bearing haplotypes. The 2.65-kb C2 DNA allele showed allelic association with HLA-B44 and C4B*Q0 and may help to further characterize the haplotype B44-Bf*S-C4A*3-C4B*Q0-DR4, which has previously been described in Felty's syndrome.     

The antigenic determinants, Rg/Ch/WH, expressed by Japanese C4 allotypes

The expression of antigenic determinants, Rg/Ch/WH, on Japanese C4 allotypes has been studied. Although the Japanese C4 allotype frequencies are known to differ from Europeans, the antigenic expression of their C4 allotypes correlates with associations described previously. All 89 random donors and 17 selected donors were Rg:1,2 so neither Rg:1,-2 nor Rg:1,-2 was found. The frequency of Ch:1,-2,3 was elevated while that of Ch:1,2,3 was reduced, which was seen as a direct result of the higher frequency of B2 and B5 allotypes. None of the Japanese were Ch:1,2,-3, but this can be accounted for by the absence of the A*6,B*1 haplotype. The WH determinant, which has been associated completely with Rg:1,-2 in Caucasians, was found at a higher frequency, 32%, in association with an A*3,2,B*QO haplotype expressing Rg:1,2, which has not been described previously. Detailed investigation showed that the A3 allotype was Rg:1,2 whereas the A2 allotype only expressed Rg1 (Rg:1,-2 WH+).     

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.     

Autoimmune-associated HLA-B8-DR3 haplotypes in Asian Indians are unique in C4 complement gene copy numbers and HSP-2 1267A/G

The classical AH8.1 (HLA-A1-B8-DR3-DQ2) is the most common Caucasian haplotype, associated with several autoimmune diseases, immunologic hyperreactivity and rapid progression to the acquired immunodeficiency syndrome. However, in Asian Indians, there are multiple unique B8-DR3 haplotypes that are associated with autoimmunity and differ significantly from the common Caucasian AH8.1. The Indian HLA-A1-B8-DR3 is therefore referred to as an AH8.1 variant. The aims of this study were to compare C4A and C4B copy numbers and to identify alleles in HSP70-2 and LTA in these haplotypes. The Indian B8-DR3 haplotypes differ from the Caucasian AH8.1 at C4A and HSP70-2 loci. The Indian B8-DR3 haplotypes have 1 copy each at C4A and C4B, while the Caucasian AH8.1 has 1 copy at C4B but no C4A gene. Moreover, the Indian and Caucasian B8-DR3 haplotypes had HSP70-2 1267 (*)A, and *G alleles, respectively. By contrast, the LTA 252 *G allele occurred both in the Indian and Caucasian haplotypes. The Indian haplotypes also contained Bf*F and TNF-308*G that were different from the Caucasian equivalents Bf*S and TNF-308*A. These differences and previous studies support the hypothesis that B8-DR3-DQ2 haplotypes in Asian Indian population might have originated independently of Caucasian AH8.1 selectively through recombination and mutations. Because autoimmune disease associations are shared among these otherwise diverse haplotypes, these data strongly suggest that some shared component(s) of all these associated haplotypes may be playing a key role in such associations.     

胰岛素依赖性糖尿病病人补体第二途径B因子多态性的检测

用琼脂糖凝胶高压电泳继以免疫固定技术对30例胰岛素依赖性糖尿病(IDDM)病人进行了补体第二途径B因子(Bf)遗传多态性的检测。检测结果表明,IDDM病人的BfF的基因率频(0.3667)显著高于正常人(0.1159),P《0.001;且BfFF表型也较正常人显著增高,P《0.001,BfFF表型人群,IDDM发病的相对危险性(RR)为12.58。     

全身性红斑狼疮病人补体第二途径B因子多态性的检测

用琼脂糖凝胶高压电泳继以单相抗B因子血清免疫固定技术对81例份全身性红斑狼疮(SLE)病人血清进行了补体第二途径B因子(Bf)遗传多态性的检测。检测结果表明,SLE病人的BF F型的基因频率(0.1914)显著高于正常人(0.1159),P_(修正)<0.05。F型阳性人群SLE发病的相对危险性(RR)为1.79,亦具统计学意义(P<0.05)。     

Extended HLA haplotypes in a Carib Amerindian population: the Yucpa of the Perija Range.

Eleven MHC loci haplotypes have been defined among a Carib speaking Amerindian population; the Yucpa, inhabiting the northern section of the Perija Range, on the limits between Colombia and Venezuela. This tribe has been known with the name of "Motilones mansos" and is located close to the Chibcha-Paeze speaking Bari or "Motilones bravos." Seventy-three full blooded Yucpa living at the villages of Aroy, Marewa, and Peraya, were selected using a genealogy previously collected by an anthropologist and tested for Bf-C4AB complement allotypes and by serology, high resolution PCR-SSO and SBT typing for HLA class 1 and class 2 alleles. Combinations of 6 HLA-A, 6 HLA-B, 5 HLA-C, 1 Bf, 3 C4AB, 3 DQA1, 3DQB1 and 2 DPA1 and 2 DPB1 alleles present in this population originate 17 different haplotypes, 3 of which represent 63% of the haplotypic constitution of the tribe. The presence of 13 individuals homozygous for 11-loci haplotypes corroborates the existence of the following allelic combinations: DRB1*0411 DQA1*03011 DQB1*0302 DPA1*01 DPB1*0402 with HLA-A*6801 C*0702 B*3909 BfS C4 32 (f = 0.3372) or with A*0204 C*0702 B*3905 (f = 0.1977) and a third haplotype which differs only in DRB1*0403 and A*2402 (f = 0.0930). The results demonstrate the isolation of the tribe and the existence of high frequencies of a reduced number of "Amerindian" ancestral and novel class 1 and class 2 alleles (B*1522, DRB1*0807) with significant linkage disequilibria. These results will be useful to test the hypothesis that differentiation of Amerindian tribal groups will have to rely on haplotypes and micropolymorphism rather than allelic lineage frequencies due to the uniformity shown thus far by the putative descendants of the original Paleo-Indians.     

Haplotypes bearing HLA-A, -B, and -DR: Bf and C4 genes in rheumatoid arthritis families

We have compared haplotypes bearing HLA-A, -B, -DR; Bf and C4 genes in 54 rheumatoid arthritis (RA) and 24 control families. There was no statistically significant differences in C4A or C4B gene frequencies between RA and control groups, although there were trends for C4B*Q0 to be reduced and C4B2 to be increased in DR4 positive RA compared with DR4 positive controls. The lack of any strong association between C4 variants and RA overall makes it unlikely that the association between RA and genes within the MHS represents a direct effect of variants within the C4A or C4B loci themselves. On comparison of DR4-bearing haplotypes, the haplotype B15-BfS-DR4 was increased fourfold and the B44-Bfs-DR4 haplotype was less frequent in the RA group. When C4 variants were also considered, the haplotype B44-C4B*Q0-C4A3-BfS-DR4 was nine times less frequent in RA patients than in controls. The observation that different DR4 bearing haplotypes may confer either increased or decreased susceptibility to RA suggests either that it is unlikely that DR4 itself is involved in the disease process or that specific haplotypic combinations are important. Thirty-two RA patients were HLA-DR4 negative. No single DR4 negative haplotype was found to confer significantly increased susceptibility to RA.     

Polymorphism of C4 and factor B in type I diabetes

The haplotypic frequencies of the fourth component of complement (C4) and factor B (Bf) have been determined in 44 Alsatian type 1 diabetics. An increased frequency of the rare allele Bf F1 (9.1% vs 1.5%) and of the silent alleles of C4 (C4 AQO: 21.6% vers 15.5% -C4 BQO: 29.6% vs 16.0%) was observed in diabetics in comparison to the general population of the same geographic area. A complete HLA haplotype determination has been obtained in 24 type 1 French diabetics. Three haplotypes were associated with the diabetic susceptibility: HLA-A30 CW5 B18 BfF1 C4A3BQO DR3 (18.75% vs 0.86%), HLA-A1 CW7 B8 BfS C4AQOB1 DR3 (15.58% vs 4.17%), HLA-A2 CW3 BW62 BfS C4A3B3 DR4 (6.25% vs 0.45%). The authors suggest that the silent alleles of C4 could modulate the expression of the diabetic susceptibility genes by lowering of the serum C4 hemolytic activity.     

HLA-linked genetic markers in Chinese and other Oriental populations

The polymorphic variants of the HLA-linked genetic markers Bf, C2, C4 and GLO—I were studied in three mongoloid populations. Analysis of linkage disequilibrium between these markers and HLA-A, B, C and DR antigens was carried out on test results from 140 unrelated Chinese individuals. The phenotypes BfS and GLO-2 were found at significantly higher frequencies than in Caucasians. BfS was associated with B12 in Japanese but not in Chinese. A single individual with the rare Bf variant SI was found. No C2 deficient individuals were observed. The C2C (common) allele occurred at a gene frequency of 0.949 and the more basic allele C2B at 0.039. The acidic variant, C2A, was observed at a frequency of 0.011 and appeared to be associated with BfF. Eighty-nine per cent of the Chinese were phenotypically C4FS. In contrast to Bf and C2, each of which is coded for by codominant alleles at a single genetic locus, C4 is coded for by two genes, C4F (Rodgers) and C4S (Chido). The C4F locus allele, C4F1 (extra fast), was strongly associated with HLA-B17, as has been found in other populations, but a new association of the C4S locus deficiency allele, C4s° (Ch-), with B17 was also observed. All HLA-B17;C4s° haplotypes were BfS positive. As has been previously found in Caucasian populations, individuals of the C4F phenotype (i.e. genotypically Fs°Fs°) were all found to be Chido negative. The frequencies of the various HLA-linked genetic markers, however, as much as the frequencies and associations of the HLA antigens themselves, distinguish these populations from other ethnic groups.     

Relationship Between the Reactivity to Hepatitis B Virus Vaccination and the Frequency of MHC Class I, II and III Alleles in Haemodialysis Patients

To study the immunoreactivity genes in a heterogeneous human population needs a large number of individuals. Associations between HLA antigens and immunoresponse to viral or bacterial antigens have been studied with controversial results. As a homogeneous population, the MHC class I, II and III allele distribution was studied in 153 end-stage renal disease patients (ESRD, average duration of renal replacement: 8.2+5.1 years) immunized with a recombinant hepatitis B vaccine in accordance to the standard vaccination schedule. Thirty-four patients with an antibody titre of less than 10 U/l following the last booster injection were considered as non-responders while 119 patients with antibody titre equal to or more than 10 U/l were considered as responders. The responder group was divided into two subgroups: low responders (antibody titre: 1000 U/l) and high responders (antibody titre: > 1000 U/ 1). Marked differences were observed between responders and non-responders in the occurrence of carriers of different MHC class I, II and III alleles. Homozygotes for HLA—A1, HLA—B8, HLA—DR3 and HLA—DQ2 were found almost exclusively in the non-responder group and significantly more heterozygotes for these alleles were found in the non-responder group compared to the responders. Similar albeit less marked differences were found in the frequency of some MHC class III alleles (C4A*6, C4A*QO, Bf*F, BPS0.7). Within the responder group, carriers of HLA—A2, HLA—B7 and HLA—DR4 were found to be clustered in the low responder sub-group whereas carriers of HLA—A1, HLA—B27, HLA—Cw2, C4A*6 and Bf*F were observed more frequently in the group of high responders. Similar differences were found with extended haplotypes as well. For example, the extended haplotypes HLA—Al, B8, BfS, C4AQO, C4B1, DR3, DQ2 and HLA—A1, B8, BfF, C4A6, C4B2, DR3, DQ2 were present in nine of 34 cases of non-responders but only in one of 119 case of responders (P <0.000001). These observations indicate that the presence or absence of certain MHC alleles even in heterozygous form determine the responsiveness to hepatitis B vaccination in end-stage renal disease patients, and among responders, the intensity of antibody response is also markedly influence by immunogenetic factors.     

A new duplication at the C4B locus associated with the HLA-Aw68, Cw8, Bw65 haplotype

A family with a cross-over between HLA-B and HLA-DR was analysed for its complement alleles. This allowed location of the cross-over between HLA-B and C4. Furthermore, the same family showed a previously undescribed duplication at the C4B locus (C4B* 2,2) that was associated with the HLA-Aw68, Cw8, Bw65, C2*1, Bf*S, C4A*2, DR7, DQw2 haplotype.