AJMB

Association of HLA-DRB1, DQA1 and DQB1 Alleles and Haplotypes with Common Variable Immunodeficiency in Iranian Patients

PDF - Export to EndNote - PubMed Central XML format - PubMed Central XML format - PubMed Central XML format
PMID: 23408509 (PubMed) - PMCID: PMC3558207 - View online: PubReader
Volume 4, Issue 2, April-June , Page 103 to 112
Tuesday, January 31, 2012 :Received , Saturday, February 25, 2012 :Accepted


  • - National Cell Bank of Iran, Pasteur Institute of Iran, Tehran, Iran

  • - National Cell Bank of Iran, Pasteur Institute of Iran, Tehran, Iran
    - Department of Immunology, Faculty of Medicine, Tehran University of Medical Sciences, Tehran, Iran

  • - National Cell Bank of Iran, Pasteur Institute of Iran, Tehran, Iran

  • - Research Center for Immunodeficiencies, Pediatrics Center of Excellence, Children's Medical Center , Tehran, Iran
  • Corresponding author National Cell Bank of Iran, Pasteur Institute of Iran, Tehran, Iran, Tel: +98 21 66492595; Email: mashokrgozar@pasteur.ac.ir
    - National Cell Bank of Iran, Pasteur Institute of Iran, Tehran, Iran

  • - National Cell Bank of Iran, Pasteur Institute of Iran, Tehran, Iran
    - Department of Immunology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran

Abstract: Common Variable Immunodeficiency (CVID) is an antibody deficiency syndrome that often co-occurs in families with selective IgA deficiency (IgAD). This study was designed to investigate the frequency of DR and DQ loci of HLA class II region in common variable immunodeficiency (CVID) patients. Fifteen Iranian patients with CVID or IgAD (mean age 14.6±5.4, range 4-25 years; 9 male and 6 female) and 63 healthy controls were studied. Establishment of B-lymphoblastoid cell lines was performed using Epstein-Barr-virus (EBV) immortalization technique and HLA alleles were typed using polymerase chain reaction based on sequence specific primers (PCR-SSP). DRB1 alleles including DRB1 *04 (p=0.03) and DRB1 *11 (p=0.01) significantly showed higher frequency in the studied subjects. In contrast, DRB1 *301 (p=0.04) and DRB1 *07 (p=0.02) alleles were negatively associated with CVID. For DQB1 and DQA1 loci, DQB1 *0302 (p=0.047) and DQA1 *03011 (p=0.001) demonstrated high frequency in cases, while DQB1 *0201 (p=0.02) and DQA1 *0201 (p=0.01) were detected to be low when compared to controls. Haplotype analysis indicated that frequency of DRB1*04-DQB1*03011-DQA1 *03011 (p=0.02), DRB1 *11-DQB1 *03011-DQA1 *0505 (p=0.047), DRB1 *11-DQA1 *0505 (p=0.04) and DRB1*04-DQA1*03011 (p=0.02) haplotypes were significantly higher in patient group, while only the frequency of the DRB1 *07-DQA1 *0201 haplotype gene was statistically lower in control group (p=0.02). According to the results, it could be deduced that the HLA-DR and DQ loci may contribute to the pathogenesis of CVID or they might be considered as suitable markers for the possibility of the occurrence of this genetic defect.

 

 

Introduction :
Common Variable Immunodeficiency (CVID) is a heterogeneous condition characterized by B cell differentiation arrest and impaired antibody responses. The etiology of CVID has been undefined for more than 85% of CVID patients yet (1,2). CVID has been reported to affect males and females equally and it has been diagnosed in various races. Although the usual age of appearance of the disease is between the second or third decades of life, other reports described the onset of clinical complications as early as the first decade of life. On the other hand, there is a noticeable variability in the incidence of the disease in different ethnic populations and the estimated incidence of CVID in Europe, North America and other continent ranges from 1:10,000 to 1:200,000. Also, the lowest frequency of incidence has been found in Japanese (1/18000), Chinese (1/40000) and African (twenty-fold lower) descents (3-7).
In addition to the associated conditions, like recurrent infections of the respiratory and gastrointestinal systems, allergic disorders, and autoimmune symptoms, it has been found that patients with CVIDs have a 10-fold increased risk of gastric cancer (7). Evaluation of a suspected CVID usually consists of a complete blood cell count with differential white blood cell count and measurement of serum immunoglobulins level, specific antibody response and lymphocyte subsets (8). Intravenous immunoglobulin (IVIG) therapy is used in most antibody deficiencies including CVID, and also in the treatment of other autoimmune diseases (9,10).
Patients with CVID show hypo-gammaglobulinaemia in the presence of normal or near-normal B cell counts which has been named agammaglobulinemia with B cells. Also, reduced serum levels of either immunoglobulin G (IgG) or immunoglobulin A (IgA) have been reported (3).
International Union of Immunological Societies (IUIS) declared that in the severest form, patients with CVID have IgA serum levels below 0.1 g/l, IgG levels below 3.0 g/l, and usually IgM levels below 0.2 g/l (6). Furthermore, autoimmune disorders have been diagnosed mostly among relatives of selective IgA deficient individuals (SIgA-D). Most individuals with IgA deficiency had showed higher rate of autoimmunity (10%) in one of their first-degree relatives compared to an estimate of 5% in the general population (8).
Furthermore, there is an immature phenotype with the expression of IgM and IgD in CVID/SIgA-D, and they usually cannot fully develop into IgA-secreting plasma cells. Moreover, abnormalities in the cytokine network such as lack of IL-2, IL-4, IL-5, IL-10, IL-13, TGF-β, and alteration of IL-21 gene have also been proposed to play role in IgA deficiency (10,11).
Furthermore, Ig secretion by CVID B cells has been induced following infection with Epstein-Barr virus (EBV) (12). Immunoglobulin A deficiency (IgA-D) is another prevalent humoral immunodeficiency in Caucasians, but is often asymptomatic in CVID patients and B cells are affected. As mentioned, CVID may include deficiencies in other immunoglobulins as well, such as IgA and IgM deficiencies, although these deficiencies are more frequently associated with a group of other primary immunoglobulin deficiencies like agammaglobulinemia and Severe Combined Immunodeficiency (SCID). In contrast to the CVID patients, SCIDs show defects in both cellular and humoral parts of the immune system. Other components of the immune system may be normal in CVID and T-cells, the type of white cells responsible for cellular immunity, are usually manufactured at normal levels in the same individuals who have CVID and IgA deficient, although certain cell signaling components may be absent (13).
A hypothesis was that CVID and selective IgA deficiency syndrome may reflect a common underlying genetic defect because CVID and IgA-D both share clinical features (14,15). While the cases of concurrent CVID and selective IgA deficiency (SIgA-D) are occasional, familial occurrences of sIgAD and CVID have been observed in approximately 20% of cases suggesting that these heterogeneous diseases are not always clearly separable and they have a common pathogenesis and some patients with IgAD later develop CVID, and family members of patients with CVID may have only selective IgAD (14-18).
Moreover, other investigation reported cases of sIgAD developing into CVID with time and occasionally vice versa, supporting the concept that IgA deficiency and CVID lie in the spectrum of the same disease, which indicates that these conditions are closely linked and can be progressive or reversible. They may represent two phenotypic variants in a spectrum associated with the same molecular defect(s) (13-17). The etiology of CVID and IgA-D is unknown but different prevalence in various ethnic groups and familial clustering of the disorder (19,20) suggest involvement of unidentified susceptibility gene(s) in arresting B cell differentiation pathways (21,22), impairing T cell-mediated cell signaling and/or isotype class switching (23,24).
Associations between IgA deficiency and certain Major Histocompatibility Complex (MHC) alleles and haplotypes have been suggested. Furthermore, studies of families with multiple cases of sIgAD and CVID have revealed that susceptibility to CVID or IgA deficiency may be correlated with specific alleles of HLA class II genes locating in the MHC region (25-27).
The aim of the present study was to investigate whether susceptibility to CVID is associated with HLA class II alleles or haplotypes in Iranian population.

 

Materials and Methods :
Subjects: Heparinized peripheral blood was collected from 15 Iranian CVID patients consisting of 6 females and 9 males ranging from 4 to 25 years old (the mean age was 14.6±5.4 years) and 63 age matched healthy controls with no related disorder.
The diagnosis of CVID was based on reduction or lack of major serum immunoglobulin classes (panhypogamma-globulinemia) in serum, recurrent bacterial infections which involved different organs (ears, eyes, sinuses, nose, bronchi, lungs, skin, gastrointestinal tract, joints, bones, CNS and parotid glands), enlarged lymph nodes and loss of proteins from kidneys. All subjects and their families gave us their informed consent before their inclusion in this study.

EBV-immortalization of human B-cells: Establishment of B-lymphoblastoid cell lines was performed using EBV immortalization technique as described previously (28).
Briefly, peripheral blood mononuclear cells (PBMCs) were separated from heparinized peripheral blood by Histopaque (Sigma-USA) density gradient centrifugation and then transformed with EBV which had been produced by the B95.8 marmoset cell line (NCBI-C110; National Cell Bank of Iran, Pasteur Institute of Iran).
In this regard, the Peripheral Blood Mononuclear Cells (PBMCs) were re-suspended in the filtered supernatant of EBV containing Marmoset B95.8 cells. After 90 min incubation at 37ºC under 5% carbon dioxide with periodic agitation, the cells were washed with RPMI-1640 medium (Gibco BRL, Scotland) and again re-suspended in the same medium supplemented with 10% heat-inactivated fetal calf serum (FCS) (Gibco, Scotland) supplemented with 100 IU/ml penicillin, 100 g/ml streptomycin and 2.5 µg/ml Amphotericin-B (PAA, Austria).
The culture medium also contained 1 µg/ml cyclosporine A (CsA) (Sandoz, Switzerland) to prevent proliferation of memory T-cytotoxic cells. Outgrowth of immortalized B-cells was observable within 14 days post infection (25). Immortalized Lymphoblastoid B Cell Lines (LCLs) were then expanded and stored in Liquid Nitrogen Tank (LNT) after microbial quality control tests.

DNA extraction and HLA typing: First, EBV transformed LCLs were grown in RPMI-1640 containing 10% Fetal Calf Serum (FCS) at 37C and 5% CO2 atmosphere followed by genomic DNA extraction.
Briefly, genomic DNA was isolated from proteinase-K-treated lymphoblastoid cell lines by salting out method and HLA typing was performed by PCR amplification with low resolution sequence-specific primers (PCR-SSP) according to Olerup and Zetterquist procedure (29).
The HLA alleles were determined by molecular DNA typing of the MHC class-II HLA alleles in the DRB1, DQB1 and DQA1 loci in groups of CVID patients and control subjects. The PCR products were analysed by agarose gel electrophoresis investigating the absence or presence of amplified DNA fragments were visualized after staining with the ethidium bromide by agarose gel electrophoresis. The alleles were typed according to linkage among Iranian DRB1, DQA1, and DQB1 alleles.

Statistical analysis: Frequency values were compared for statistical significant by 2 X 2 contingency tables, using Chi-square analysis after Fisher exact test (one-tailed), as appropriate. The odds ratio (OR) with 95% confidence intervals (CI) was calculated and a value of p<0.05 was defined as statistically significant. Descriptive data are displayed as enumerations, percentages, or mean±1 SD.

 

Results :
Alleles frequency: Results of the HLA DRB1, DQB1 and DQA1 alleles typing in CVID patients and control group have been summarized in tables 1, 2 and 3, respectively. The data indicate that the gene frequency was higher about DRB1 alleles, because including DRB1 *04 (p=0.03) and DRB1 *11 (p=0.01) found to be significant.
On the contrary, DRB1 *301 (p=0.04) and DRB1 *07 (p=0.02) alleles were significantly decreased in CVID cases comparing to controls. For DQB1 and DQA1 loci, an increase were observed for the two alleles, the DQB1 *0302 (p=0.047) and DQA1 *03011 (p=0.001) showed an increased genotype at high frequencies. Two other alleles, DQB1 *0201 (p=0.02) and DQA1 *0201 (p=0.01) were detected at low frequencies in patients group. Most of the differences were significantly associated with CVID pathogenesis.

Haplotype frequency: HLA haplotype frequencies are displayed in tables 4 and 5. Haplotype analysis showed that the frequencies of haplotypes DRB1 *04-DQB1 *03011-DQA1 *03011 (p=0.02), DRB1 *11-DQB1 *03011-DQA1 *0505 (p=0.047), DRB1 *11-DQA1 *0505 (p=0.04) and DRB1 *04-DQA1 *03011 (p=0.02) were significantly higher, while only the frequency of the DRB1 *07-DQA1 *0201 haplotype gene was statistically lower in comparison to normal population (p=0.02).

 

Discussion :
Common variable immunodeficiency and IgA deficiency are heritable disorders that have been observed in immediate relatives and familial inheritance of either SIgAD or CVID occurs nearly in about 20% of cases (30). The MHC region located on chromosome 6 contains important polymorphic loci encoding different antigens that play a role in failure of B cell differentiation. HLA class-II molecules, which are expressed on the surface of APCs, present processed peptide fragments to T-lymphocyte receptors (TCR) and thereby restrict T-cell and B-cell responses to specific antigens (23,24). Several studies demonstrated that certain HLA alleles or haplotypes may confer susceptibility to CVID (15,26,31). However, some could not find any significant association for this locus (20).
In the present study, association of CVID with DRB1, DQB1 and DQA1 loci of the HLA region was investigated by DNA molecular typing, which allows the identification of previously serologically undefined specificities.
There were positive and negative significant associations for DQ and DR loci in HLA class II region specifically for DRB1 *04 (p=0.03), DRB1 *11(p=0.01), DQB1 *0302 (p=0.047), DQA1 *03011 (p=0.001) alleles. It was also observed that HLA-DRB1 *301 (p=0.04), DRB1 *07(p=0.02), DQB1 *0201 (p=0.02) and DQA1 *0201 (p=0.01) alleles occurred with decreased frequency among patients compared to control group, suggesting induction of resistance to the disease in the normal population.
The observed frequencies for all HLA antigens and alleles in control group were in accordance with those of a typical Caucasian population (32).
Unlike some studies that indicated a high frequency for DQB1 *0201 in patients (Table 6) (15,25,33,34), we observed a negative association for this allele in our study. It is interesting to note that the two DR7 (DRB1 *0701) and DQ2 (DQB1 *0201) alleles with negative associations in our last CVID study ((p<0.001 & p<0.05, respectively) were also in accordance with the data represented in this study (both with p<0.02) (32). For MHC haplotypes carrying HLA-DRB1 *07, Emilio G et al suggested an association in Spanish patients (35).
While based on our findings, “DRB1 *07-DQA1 *0201” haplotype showed a low frequency in patients. Moreover, another study reported more than 20% of individuals carried the HLA DR7- DQ2 haplotype, also they have observed a positive association for DR3, DR7 and DQ2 alleles which is in contrast with our results (34-37).
To evaluate the MHC susceptibility locus, most studies have focused on the B8-DR3 haplotype due to its prevalence in Caucasian CVID and IgAD patients. However, in Spanish patients HLA-DR1 and HLA-DR7 were shown to have higher frequencies than HLA-DR3 (25), which reflects the distribution of HLA-DR alleles and extended haplotypes in southern Europe (38). Furthermore, DRB1 *0102 allele and the B14-DR1 extended haplotype were more common among Italian CVID patients (31,39). Another study, with similar findings to ours, suggested that lower frequency of DRB1* 1501 conferred protection in this disorder (40).
In the present study, DRB1 *04-DQB1 *03011-DQA1 *03011 (p=0.02), DRB1 *11-DQB1 *03011-DQA1 *0505 (p=0.047), DRB1 *11-DQA1 *0505 (p=0.04) and DRB1 *04-DQA1 *03011 (p=0.02) haplotypes were observed in patients sharing susceptibility to CVID individuals.
However, DRB1 *07-DQA1 *0201 (p=0.02) haplotype was less frequent versus non-affected individuals. Among the 15 patients, only one (6.6%) had DRB1 *07-DQA1 *0201 haplotype, whereas 22 of the 63 healthy controls (34.9%) showed this haplotypes (p-value=0.02, OR: 0.13).
Several HLA-DR and DQ alleles and haplotypes have been identified to be associated with CVID/IgA deficient individuals in different racial populations (Table 6) (15,19,31,34-37,40-45).
In general the complexity of the Linkage Disequilibrium (LD) and the density of genes make the detection of the causative variants a challenging task in the HLA region. Based on the results we believe that susceptibility and resistance to IgA-D and CVID are correlated with alleles of the DRB1, DQB1 and DQA1 genes.
We hypothesize that the HLA class II molecules themselves are involved in the pathogenesis of IgA-D and CVID. Although the mechanism(s) of their effect is not known yet, it might act through auto-reactive T cells or by insufficient help from class II-restricted CD41 lymphocytes in T-cell-dependent B-cell responses, possibly due to inadequate response to infectious agents. Our different results from previous studies may be explained by the heterogeneous nature of these immunodeficiencies and/or environmental effects.
In addition, some researchers reported that certain MHC haplotypes with high frequencies found in immunodeficient patients were also observed in normal members of the family background. In another word these evidences suggest that the presences of these MHC haplotypes alone are not sufficient for appearance of the defects. Strong linkage disequilibrium between the different MHC loci, as was mentioned, makes it extremely difficult to determine the precise genes or haplotypes conferring susceptibility to these two diseases. The data strongly suggest the need for comprehensive HLA typing of large populations of CVID and IgAD patients, additional SNP mapping, and re-sequencing of candidate genes in MHC region.
As a final point, the method which we used in the present study to determine HLA alleles is very notable. B-cell immortalization with EBV technique leads to growth and purity of B lymphocytes. The purity of the B-cells resulted to significantly increased frequency of class-II antigens, which subsequently improves the accuracy of the classical HLA class-II detection assay (46).

 

Conclusion :
Considering previous data and the results of present study, differences in HLA association of IgAD and CVID compared to the other populations strongly implicate a genetic background of the disease. Furthermore, different alleles or haplotypes within the HLA class II region might be involved in the pathogenesis of these disorders and they may appear as markers for the possible genetic defect in different ethnic groups. This indicates the importance of studies to identify the associated HLA antigens in a large number of ethnic populations. However, further studies are needed.

 

Acknowledgement :
We are most grateful to Dr. Ali Jahanian and Ms. Zahra Safari for their help. This study was financially supported in part by a grant from Pasteur Institute of Iran.

 



Table 1. HLA-DQB1 allele’s frequency
Table 1. HLA-DQB1 allele’s frequency




Table 2. HLA-DQA1 allele’s frequency
Table 2. HLA-DQA1 allele’s frequency




Table 3. HLA-DRB1 allele’s frequency
Table 3. HLA-DRB1 allele’s frequency




Table 4. HLA- DRB-DQB-DQA haplotype’s frequency
Table 4. HLA- DRB-DQB-DQA haplotype’s frequency




Table 5. HLA- DRB1-DQA1 haplotype’s frequency
Table 5. HLA- DRB1-DQA1 haplotype’s frequency




Table 6. HLA alleles or haplotypes expressed in CVID/ IgA deficiency patients from different countries
Table 6. HLA alleles or haplotypes expressed in CVID/ IgA deficiency patients from different countries




References :
  1. Van de Ven AA, Compeer EB, van Montfrans JM, Boes M. B-cell defects in common variable immunodeficiency: BCR signaling, protein clustering and hardwired gene mutations. Crit Rev Immunol 2011;31(2):85-98.
  2. Cunningham-Rundles C, Bodian C. Common variable immunodeficiency: clinical and immunological features of 248 patients. Clin Immunol 1999;92(1):34-48.
  3. Webster ADB. Clinical and immunological spectrum of common variable immunodeficiency (CVID). Iran J Allergy Asthma Immunol 2004;(3)3:103-113.
  4. Hammarstrom L, Vorechovsky I, Webster D. Selective IgA deficiency (SIgAD) and common variable immunodeficiency (CVID). Clin Exp Immunol 2000;120(2):225- 231.
  5. Blancas-Galicia L, Ramírez-Vargas NG, Espinosa-Rosales F. Common variable immunodeficiency. A clinical approach. Rev Invest Clin 2010;62(6):577-582.
  6. Primary Immunodeficiency Diseases. Report of an IUIS Scientific Committee. Clin Exp Immunol 1999;118(Supplement 1):1-28.
  7. Dhalla F, da Silva SP, Lucas M, Travis S, Chapel H. Review of gastric cancer risk factors in patients with common variable immunodeficiency disorders, resulting in a proposal for a surveillance programme. Clin Exp Immunol 2011;165(1):1-7.
  8. Yel L. Selective IgA deficiency. J Clin Immunol 2010;30(1):10-16.
  9. Kaveri SV, Maddur MS, Hegde P, Lacroix-Desmazes S, Bayry J. Intravenous immunoglobulins in immunodeficiencies: more than mere replacement therapy. Clin Exp Immunol 2011;164 (Suppl 2):2-5.
  10. Borte S, Pan-Hammarström Q, Liu C, Sack U, Borte M, Wagner U, Graf D, Hammarström L. Interleukin-21 restores immunoglobulin production ex vivo in patients with common variable immunodeficiency and selective IgA deficiency. Blood 2009;114(19):4089-4098.
  11. Moise A, Nedelcu FD, Toader MA, Sora SM, Tica A, Ferastraoaru DE, Constantinescu I. Primary immunodeficiencies of the B lymphocyte. J Med Life 2010;3(1):60-63.
  12. De Gast GC, Wilkins SR, Webster AD, Rickinson A, Platts-Mills TA. Functional immaturity of isolated B cells from patients with hypogammaglobulinaemia. Clin Exp Immunol 1980; 42(3):535-544.
  13. Hammarstrom L, Smith CIE. Genetic approach to common variable immunodeficiency and IgA deficiency. In: Ochs H, Smith CI, Puck J (eds). Primary immunodeficiency diseases a molecular and genetic approach. Oxford: Oxford University Press;1999,250-262.
  14. Schaffer FM, Palermos J, Zhu ZB, Barger BO, Cooper MD, Volanakis JE. Individuals with IgA deficiency and common variable immunodeficiency share polymorphisms of major histocompatibility complex class III genes. Proc Natl Acad Sci USA 1989; 86(20):8015-8019.
  15. Olerup O, Smith CIE, Björkander J, Hammarström L. Shared HLA class II-associated genetic susceptibility and resistance, related to the HLA-DQB1 gene, in IgA deficiency and common variable immunodeficiency. Proc Natl Acad Sci USA 1992; 89(22):10653-10657.
  16. Carvalho Neves Forte W, Ferreira De Carvalho Jr F, Damaceno N, Vidal Perez F, Gonzales Lopes C, Mastroti RA. Evolution of IgA deficiency to IgG subclass deficiency and common variable immunodeficiency. Allergol Immunopathol 2000; 28(1):18-20.
  17. Español T, Catala M, Hernandez M, Caragol I, Bertran JM. Development of a common variable immunodeficiency in IgA deficient patients. Clin Immunol Immunopathol 1996;80(3 Pt 1):333-335.
  18. Ishizaka A, Nakanishi M, Yamada S, Sakiyama Y, Matsumoto S. Development of hypogammaglobulinaemia in a patient with common variable immunodeficiency. Eur J Pediatr 1989;149(3):175–176.
  19. Koistinen J. Familial clustering of selective IgA deficiency. Vox Sang 1976; 30(3):181-190.
  20. Oen K, Petty RE, Schroeder ML. Immunoglobulin A deficiency: genetic studies. Tissue Antigens 1982;19(3):174-182.
  21. Conley ME, Cooper MD. Immature IgA B cells in IgA deficient patients. N Engl J Med 1981;305(9):495-497.
  22. Cooper MD, Lawton AR, Bockman DE. Agammaglobulinaemia with B lymphocytes. Specific defect of plasma-cell differentiation. Lancet 1971;2(7728):791-794.
  23. Eisenstein EM, Chua K, Strober W. B cell differentiation defects in common variable immunodeficiency are ameliorated after stimulation with anti-CD40 antibody and IL- 10. J Immunol 1994;152(12):5957-5968.
  24. Farrington M, Grosmaire LS, Nonoyama S, Fischer SH, Hollenbaugh D, Ledbetter JA, et al. CD40 ligand expression is defective in a subset of patients with common variable immunodeficiency. Proc Natl Acad Sci USA 1994; 91(3):1099-1103.
  25. De La Concha EG, Fernandez-Arquero M, Martinez A, Vidal F, Vigil P, Conejero L, et al. HLA class II homozygosity confers susceptibility to common variable immunodeficiency (CVID). Clin Exp Immunol 1999;116(3):516-520.
  26. Olerup O, Smith CIE, Hammarström L. Different amino acids at position 57 of the HLA-DQβ chain associated with susceptibility and resistance to IgA deficiency. Nature 1990;347(6290):289-290.
  27. Schroeder HW Jr, Zhu ZB, March RE, Campbell RD, Berney SM, Nedospasov SA, et al. Susceptibility locus for IgA deficiency and common variable immunodeficiency in the HLA-DR3, -B8,-A1 haplotypes. Mol Med 1998;4(2):72-86.
  28. Shokri F, Mageed RA, Maziak BR, Jefferis R. Expression of VHIII-associated cross-reactive idiotype on human B lymphocytes. Association with staphylococcal protein A binding and Staphylococcus aureus Cowan I stimulation. J Immunol 1991;146(3):936-940.
  29. Olerup O, Zetterquist H. HLA-DR typing by PCR amplification with sequence-specific primers (PCR-SSP) in 2 hours: an alternative to serological DR typing in clinical practice including donor-recipient matching in cadaveric transplantation. Tissue Antigens 1992;39(5):225-235.
  30. Wollheim FA, Belfrage S, Coster C, Lindholm H. Primary "acquired" hypogammaglobulinemia; clinical and genetic aspects of nine cases. Acta Med Scand 1964;176:1-16.
  31. Fiore M, Pera C, Delfino L, Scotese I, Ferrara GB, Pignata C. DNA typing of DQ and DR alleles in IgA-deficient subjects. Eur J Immunogenet 1995;22(5):403-411.
  32. Amanzadeh A, Shokrgozar M.A, Samadi-Bahrami Z, Aghamohammadi A, Shokri F. Frequency analysis of HLA antigens in Iranian patients with common variable immunodeficiency. Arch Iranian Med 2003;6(1):16-22.
  33. Olerup O, Smith CI, Hammarstrom L. Is selective IgA deficiency associated with central HLA genes or alleles of the DR-DQ region? Immunol Today 1991;12(4):134-136.
  34. MacHulla HK, Schönermarck U, Schaaf A, Müller LP, Kloss C, Krüger J, Kunze G, et al. HLA-A, B, Cw and DRB1, DRB3/4/5/, DQB1, DPB1 frequencies in German immunoglobulin A-deficient individuals. Scand J Immunol 2000;52(2):207-211.
  35. De la Concha EG, Fernandez-Arquero M, Gual L, Vigil P, Martinez A, Urcelay E, et al. MHC susceptibility genes to IgA deficiency are located in different regions on different HLA haplotypes. J Immunol 2002;169(8);4637-4643.
  36. Mohammadi J, Pourpak Z, Jarefors S, Saghafi S, Zendehdel K, Pourfathollah AA, et al. Human leukocyte antigens (HLA) associated with selective IgA deficiency in Iran and Sweden. Iran J Allergy Asthma Immunol 2008;7(4):209-214.
  37. Mohammadi J, Ramanujam R, Jarefors S, Rezaei N, Aghamohammadi A, Gregersen PK, et al. IgA deficiency and the MHC: assessment of relative risk and microheterogeneity within the HLA A1 B8, DR3 (8.1) haplotype. J Clin Immunol 2010;30(1):138-143.
  38. Imanishi T, Akaza T, Kimura A, Tokunaga K, Gojobori T. Allele and haplotype frequencies for HLA and complement loci in various ethnic groups. In: Tsuji K, Aizawa M, Sasazuki T, eds. HLA 1991. Proceedings of the 11th International Histocompatibility Workshop and Conference. Vol 1. Oxford: Oxford University Press;1992:1067-1074,1141-1149.
  39. Cuccia-Belvedere M, Monafo V, Martinetti M, Plebani A, De Paoli F, Burgio GR. Recurrent extended HLA haplotypes in children with selective IgA deficiency. Tissue Antigens 1989;34(2):127-132.
  40. Wang N, Shen N, Vyse TJ, Anand V, Gunnarson I, Sturfelt G, et al. Selective IgA deficiency in autoimmune diseases. Mol Med 2011;17(11-12)1383-1396.
  41. Waldrep ML, Zhuang Y, Schroeder HW Jr. Analysis of TACI mutations in CVID & RESPI patients who have inherited HLA B*44 or HLA*B8. BMC Med Genet 2009; 10:100.
  42. Ferreira RC, Pan-Hammarström Q, Graham RR, Gateva V, Fontán G, Lee AT, et al. Association of IFIH1 and other autoimmunity risk alleles with selective IgA deficiency. Nat Genet 2010;42(9):777-780.
  43. Pozo ND, Medrano LM, Cénit MC, Fernández-Arquero M, Ferreira A, García-Rodríguez MC, et al. MSH5 is not a genetic predisposing factor for immunoglobulin A deficiency but marks the HLA-DRB1*0102 subgroup carrying susceptibility. Hum Immunol 2010;71(9):861-864.
  44. Mullighan CG, Fanning GC, Chapel HM, Welsh KI. TNF and lymphotoxin-alpha polymorphisms associated with common variable immunodeficiency: role in the pathogenesis of granulomatous disease. J Immunol 1997;159(12):6236-6241.
  45. Czyzewska-Buczyñska A, Majkowska-Skrobek G, Jankowski A. Association of HLA-*08:DRB1*03 with immunoglobulin A-deficiency. Indian J Pediatr 2007;74 (11):1021-1024.
  46. Avila-Cariño J, Lewin N, Yamamoto K, Tomita Y, Mellstedt H, Brodin B, et al. EBV infection of B-CLL cells in vitro potentiates their allostimulatory capacity if accompanied by acquisition of the activated phenotype. Int J Cancer 1994;58(5):678-685.