In vitro cytokine production by HLA-B8,DR3 positive subjects

Pathogenesis of systemic lupus erythematosus: risks, mechanisms and therapeutic targets

Research elucidating the pathogenesis of systemic lupus erythematosus (SLE) has defined two critical families of mediators, type I interferon (IFN-I) and autoantibodies targeting nucleic acids and nucleic acid-binding proteins, as fundamental contributors to the disease. On the fertile background of significant genetic risk, a triggering stimulus, perhaps microbial, induces IFN-I, autoantibody production or most likely both. When innate and adaptive immune system cells are engaged and collaborate in the autoimmune response, clinical SLE can develop. This review describes recent data from genetic analyses of patients with SLE, along with current studies of innate and adaptive immune function that contribute to sustained IFN-I pathway activation, immune activation and autoantibody production, generation of inflammatory mediators and tissue damage. The goal of these studies is to understand disease mechanisms, identify therapeutic targets and stimulate development of therapeutics that can achieve improved outcomes for patients.

Are the integrin binding motifs within SARS CoV-2 spike protein and MHC class II alleles playing the key role in COVID-19?

The previous studies on the RGD motif (aa403-405) within the SARS CoV-2 spike (S) protein receptor binding domain (RBD) suggest that the RGD motif binding integrin(s) may play an important role in infection of the host cells. We also discussed the possible role of two other integrin binding motifs that are present in S protein: LDI (aa585-587) and ECD (661-663), the motifs used by some other viruses in the course of infection. The MultiFOLD models for protein structure analysis have shown that the ECD motif is clearly accessible in the S protein, whereas the RGD and LDI motifs are partially accessible. Furthermore, the amino acids that are present in Epstein-Barr virus protein (EBV) gp42 playing very important role in binding to the HLA-DRB1 molecule and in the subsequent immune response evasion, are also present in the S protein heptad repeat-2. Our MultiFOLD model analyses have shown that these amino acids are clearly accessible on the surface in each S protein chain as monomers and in the homotrimer complex and bind to HLA-DRB1 β chain. Therefore, they may have the identical role in SARS CoV-2 immune evasion as in EBV infection. The prediction analyses of the MHC class II binding peptides within the S protein have shown that the RGD motif is present in the core 9-mer peptide IRGDEVRQI within the two HLA-DRB1*03:01 and HLA-DRB3*01.01 strong binding 15-mer peptides suggesting that RGD motif may be the potential immune epitope. Accordingly, infected HLA-DRB1*03:01 or HLA-DRB3*01.01 positive individuals may develop high affinity anti-RGD motif antibodies that react with the RGD motif in the host proteins, like fibrinogen, thrombin or von Willebrand factor, affecting haemostasis or participating in autoimmune disorders.

Association of polymorphism -308G/A in tumor necrosis factor-alpha gene (TNF-α) and TNF-α serum levels in patients with relapsing-remitting multiple sclerosis

TNF-α is an important cytokine of the inflammatory response involved in the pathogenesis of relapsing-remitting multiple sclerosis (RRMS). The aim of this study is to explore the association between the promoter polymorphism -308G/A in the TNF-α gene (rs1800629) with genetic susceptibility to RRMS.Methods: A group of 183 RRMS patients and 169 age and gender-matched healthy controls were enrolled in the study. Genotyping of the polymorphism was performed by PCR-restriction fragment length polymorphism and quantification of TNF-α serum levels was conducted by ELISA.Results: The genotype distribution in female patients showed a significantly elevated frequency of heterozygotes (AG) (23.5% vs. 12.8%, OR = 2.072, p = 0.029) in comparison with the healthy women. Substantially higher TNF-α serum levels were observed in females compared to males, in both patients and healthy controls (p < 0.05). According to the genotype, TNF-α levels in the RRMS group were calculated in the following order: for GA/AA genotypes (5.67pg/ml vs. 3.48pg/ml, p = 0.0031) and for GG genotypes (4.58pg/ml vs. 3.52pg/ml, p = 0.00043). Moreover, the carriers of at least one A-allele of -308G/A TNF-α polymorphism (GA+AA) are significantly associated with two fold increased risk for RRMS development (OR = 1.950; p = 0.042) in women in contrast to men as well as associated with early onset of the disease (OR = 2.400; p = 0.021).Conclusion: Our study showed that the level of TNF-α in the serum of patients with RRMS showed a significant association with the -308G/A TNF-α polymorphism and gender dependency.

Chinese woodchucks with different susceptibility to WHV infection differ in their genetic background exemplified by cytochrome B and MHC-DRB molecules

BACKGROUND

Chinese woodchucks (M. himalayana) were recently found to be susceptible to woodchuck hepatitis virus (WHV) infection. In this study, we aimed to determine the susceptibility to WHV infection of M. himalayana from different areas and their association with the animal genetic background exemplified by cytochrome B and MHC-DRB molecules.

METHODS

Animals from four different areas in Qinghai province were inoculated with WHV59 strains. The virological markers including WHV surface antigen (WHsAg), WHV core antibody (WHcAb), and WHV DNA in serum were measured by ELISA and Real-time PCR, respectively. The sequences of cytochrome B gene and MHC-DRB molecules were obtained and sorted with Clustalx software. The nucleotide variation sites were identified using MEGA5 software.

RESULTS

The animals from four different areas had different susceptibility to WHV infection. Animals from TR and TD areas had a high level of long-lasting viremia, while those from GD and WL areas had a low level of transient viremia after WHV inoculation. All of the animals belong to the same subspecies M. himalayana robusta identified by cytochrome B gene sequences. Based on their nucleotide variation pattern, 8 alleles of cytochrome B gene were identified, and 7 MHC-DRB alleles were identified. Allele A of cytochrome B and Allele Mamo-DRB1*02 of MHC-DRB was found to be frequent in animals from TR and TD areas, while Allele H of cytochrome B and Allele Mamo-DRB1*07 of MHC-DRB was predominant in animals from GD and WL areas.

CONCLUSION

Chinese woodchucks from different areas differed in their susceptibility to WHV infection, though they belong to the same subspecies M. himalayana robusta. The genetic background exemplified by cytochrome B and MHC-DRB differed in Chinese woodchucks with different susceptibility to WHV infection.

Analysis of cellular and humoral immune responses against cytomegalovirus in patients with autoimmune Addison's disease

Background

Autoimmune Addison’s disease (AAD) is caused by multiple genetic and environmental factors. Variants of genes encoding immunologically important proteins such as the HLA molecules are strongly associated with AAD, but any environmental risk factors have yet to be defined. We hypothesized that primary or reactivating infections with cytomegalovirus (CMV) could represent an environmental risk factor in AAD, and that CMV specific CD8⁺ T cell responses may be dysregulated, possibly leading to a suboptimal control of CMV. In particular, the objective was to assess the HLA-B8 restricted CD8⁺ T cell response to CMV since this HLA class I variant is a genetic risk factor for AAD.

Methods

To examine the CD8⁺ T cell response in detail, we analyzed the HLA-A2 and HLA-B8 restricted responses in AAD patients and healthy controls seropositive for CMV antibodies using HLA multimer technology, IFN-γ ELISpot and a CD107a based degranulation assay.

Results

No differences between patients and controls were found in functions or frequencies of CMV-specific T cells, regardless if the analyses were performed ex vivo or after in vitro stimulation and expansion. However, individual patients showed signs of reactivating CMV infection correlating with poor CD8⁺ T cell responses to the virus, and a concomitant upregulation of interferon regulated genes in peripheral blood cells. Several recently diagnosed AAD patients also showed serological signs of ongoing primary CMV infection.

Conclusions

CMV infection does not appear to be a major environmental risk factor in AAD, but may represent a precipitating factor in individual patients.

Electronic supplementary material

The online version of this article (doi:10.1186/s12967-016-0822-z) contains supplementary material, which is available to authorized users.

DDX39B (BAT1), TNF and IL6 gene polymorphisms and association with clinical outcomes of patients with Plasmodium vivax malaria

BACKGROUND

DDX39B (BAT1) encodes an RNA helicase known to regulate expression of TNF and IL-6. Elevated levels of these two cytokines are associated with increased severity of clinical malaria. The aim of this study was to investigate the relationship between single nucleotide polymorphisms (SNPs) in the DDX39B, TNF and IL6 genes and the clinical outcomes of patients with Plasmodium vivax malaria.

METHODS

Cross-sectional investigations were carried out in two regions of the Brazilian Amazon where several studies on the pathogenesis of vivax malaria had been performed. Individuals were categorized according to infection status as well as clinical presentation into the following groups: uninfected, asymptomatic infection, mild infection, or complicated infection. Polymorphisms were identified using PCR restriction fragment-length polymorphism analysis and the restriction enzymes NlaIII or NcoI. The plasma levels of cytokines were determined using ELISA.

RESULTS

The G allele of DDX39B-22C > G was associated with absent or decreased manifestations of malaria and the C allele was a risk factor for disease complications. Study participants heterozygous for TNF-308 (GA) and DDX39B-348 (CT) had higher TNF levels than wild-type participants. Haplotypes that included DDX39B (-22C > G and -348C > T) and TNF polymorphisms were not directly associated with mild or complicated malaria infections; however, haplotypes AGC, ACC, GGT, AGT and ACT were associated with increased TNF levels. Participants with genotype combinations GC/CC/GG/GG and GG/CT/GG/GG (DDX39B-22/DDX39B-348/TNF-308/IL6-176) had decreased and increased risk of mild malaria, respectively, compared with asymptomatic and uninfected participants. GC/CC/GG/GG was linked to decreased TNF and IL-6 levels.

CONCLUSIONS

This is the first study to describe patients with DDX39B and IL6 SNPs who had vivax malaria. These findings support the postulation that a set of mutations in immune-related genes is associated with inflammatory mediators and the clinical outcomes of patients with malaria.

Immunogenetic factors affecting susceptibility of humans and rodents to hantaviruses and the clinical course of hantaviral disease in humans

We reviewed the associations of immunity-related genes with susceptibility of humans and rodents to hantaviruses, and with severity of hantaviral diseases in humans. Several class I and class II HLA haplotypes were linked with severe or benign hantavirus infections, and these haplotypes varied among localities and hantaviruses. The polymorphism of other immunity-related genes including the C4A gene and a high-producing genotype of TNF gene associated with severe PUUV infection. Additional genes that may contribute to disease or to PUUV infection severity include non-carriage of the interleukin-1 receptor antagonist (IL-1RA) allele 2 and IL-1β (-511) allele 2, polymorphisms of plasminogen activator inhibitor (PAI-1) and platelet GP1a. In addition, immunogenetic studies have been conducted to identify mechanisms that could be linked with the persistence/clearance of hantaviruses in reservoirs. Persistence was associated during experimental infections with an upregulation of anti-inflammatory responses. Using natural rodent population samples, polymorphisms and/or expression levels of several genes have been analyzed. These genes were selected based on the literature of rodent or human/hantavirus interactions (some Mhc class II genes, Tnf promoter, and genes encoding the proteins TLR4, TLR7, Mx2 and β3 integrin). The comparison of genetic differentiation estimated between bank vole populations sampled over Europe, at neutral and candidate genes, has allowed to evidence signatures of selection for Tnf, Mx2 and the Drb Mhc class II genes. Altogether, these results corroborated the hypothesis of an evolution of tolerance strategies in rodents. We finally discuss the importance of these results from the medical and epidemiological perspectives.

The pathogenesis of nephropathia epidemica: new knowledge and unanswered questions

Puumala virus (PUUV) causes an acute hemorrhagic fever with renal syndrome (HFRS), a zoonosis also called nephropathia epidemica (NE). The reservoir host of PUUV is the bank vole (Myodes glareolus). Herein we review the main clinical manifestations of NE, acute kidney injury, increased vascular permeability, coagulation abnormalities as well as pulmonary, cardiac, central nervous system and ocular manifestations of the disease. Several biomarkers of disease severity have recently been discovered: interleukin-6, pentraxin-3, C-reactive protein, indoleamine 2,3-dioxygenase, cell-free DNA, soluble urokinase-type plasminogen activator, GATA-3 and Mac-2 binding protein. The role of cytokines, vascular endothelial growth hormone, complement, bradykinin, cellular immune response and other mechanisms in the pathogenesis of NE as well as host genetic factors will be discussed. Finally therapeutic aspects and directions for further research will be handled.

Serum levels of soluble IL-2R, CD4 and CD8 in bronChial asthma

The aim of the present study was to compare serum levels of soluble forms of interleukin-2 receptor, CD4 and CD8, released by lymphocytes during activation of the immune system, in patients with allergic bronchial asthma, with those in healthy subjects. Significantly higher levels of soluble IL-2R and soluble CD4 were found in patients with asthma compared with the control group. In contrast, lower levels of soluble CD8 values were found in patients with asthma compared to the control group. Significant correlations were found for both sIL-2R and sCD4 and these two molecules, with lung function measured as bronchial responsiveness to inhaled methacholine. These results strengthen previous suggestions that in allergic bronchial asthma, activation of T cells plays a significant role in the disease pathogenesis.

HLA-associated hemorrhagic fever with renal syndrome disease progression in slovenian patients

Major histocompatibility complex (MHC) class I and class II genes regulate the balance between appropriate aggressive responses and invading pathogens while minimizing the destruction of host tissue. Several studies have shown that in hemorrhagic fever with renal syndrome (HFRS) patients, the disease outcome is determined by a complex interaction between the virus and immunopathologic and human genetic factors. In Slovenia, the severity of the disease caused by Puumala virus (PUUV) is significantly lower than that of HFRS due to Dobrava virus (DOBV). We have determined 23 different HLA-B and 12 different HLA-DRB1 types in Slovenian HFRS patients. Comparison of HLA frequencies between healthy individuals and HFRS patients showed no strong association with the susceptibility for hantaviral infection. Significant associations were recognized when the patient group was separated according to the virus responsible for the infection. DOBV-infected patients have a significantly higher frequency of HLA-B*35 than PUUV-infected patients. For HLA class II genes, the biggest difference between the PUUV- and DOBV-infected groups of patients was in HLA-DRB1*13, where this phenotype was more frequent in PUUV-infected patients, especially in the severe form of the disease. HLA-B*07 could play a protective role in PUUV-caused HFRS in the Slovenian population. Our study shows diverse associations of HLA molecules with DOBV- and PUUV-induced HFRS, and therefore, we presume that different hantaviruses are presented differently through the same HLA molecules and that this might lead to either a more severe or a milder form of the disease. In line with this idea, we have noticed that HLA-B*35 might be a genetic risk factor for DOBV infection in the Slovenian population.

Human leucocyte antigens and cytokine gene polymorphisms and tuberculosis

PURPOSE

Several genes encoding different cytokines and human leucocyte antigens (HLA) may play crucial roles in host susceptibility to tuberculosis (TB). Our objective was to investigate whether these genes might be associated with protection from or susceptibility to TB.

MATERIALS AND METHODS

Genomic DNA from patients with TB (n = 30) and ethnically matched controls (n = 30) was genotyped by using sequence-specific primers-polymerase chain reaction and sequence-specific oligonucletid methods.

RESULTS

Our results demonstrated that HLA-CwFNx0101 [P = 0.05, odds ration (OR) (95% confidence interval) = 2.269 (1.702-3.027)] allele frequency was significantly more common in TB patients than in healthy controls, and HLA-CwFNx0101 may be associated with susceptibility to TB. Analysis of cytokine allele frequencies showed that interleukin (IL)-10, -819 C and -592 C alleles was significantly more common in TB patients than in controls (pc: 0.038 and 0.017, respectively). From the IL-10 cluster, a positive significant difference was found at positions -1082 and -592 C/C (pc: 0.027 and 0.054, respectively) genotypes. Although these differences could be explained by the highest frequency of C/C and G/G homozygous patients with TB, in contrast to the control group, statistically significant differences for the C/C genotype however were lost after Bonferroni correction of the P-values.

CONCLUSION

Altogether, our results suggest that the polymorphisms in HLA (class I) and cytokine (IL-10) genes may affect the susceptibility to TB and increase the risk of developing the disease.

Several regions in the major histocompatibility complex confer risk for anti-CCP-antibody positive rheumatoid arthritis, independent of the DRB1 locus

Recent evidence suggests that additional risk loci for RA are present in the major histocompatibility complex (MHC), independent of the class II HLA-DRB1 locus. We have now tested a total of 1,769 SNPs across 7.5Mb of the MHC located from 6p22.2 (26.03 Mb) to 6p21.32 (33.59 Mb) derived from the Illumina 550K Beadchip (Illumina, San Diego, CA, USA). For an initial analysis in the whole dataset (869 RA CCP + cases, 1,193 controls), the strongest association signal was observed in markers near the HLA-DRB1 locus, with additional evidence for association extending out into the Class I HLA region. To avoid confounding that may arise due to linkage disequilibrium with DRB1 alleles, we analyzed a subset of the data by matching cases and controls by DRB1 genotype (both alleles matched 1:1), yielding a set of 372 cases with 372 controls. This analysis revealed the presence of at least two regions of association with RA in the Class I region, independent of DRB1 genotype. SNP alleles found on the conserved A1-B8-DR3 (8.1) haplotype show the strongest evidence of positive association (P ~ 0.00005) clustered in the region around the HLA-C locus. In addition, we identified risk alleles that are not present on the 8.1 haplotype, with maximal association signals (P ~ 0.001-0.0027) located near the ZNF311 locus. This latter association is enriched in DRB1*0404 individuals. Finally, several additional association signals were found in the extreme centromeric portion of the MHC, in regions containing the DOB1, TAP2, DPB1, and COL11A2 genes. These data emphasize that further analysis of the MHC is likely to reveal genetic risk factors for rheumatoid arthritis that are independent of the DRB1 shared epitope alleles.

Influence of HLA-DRB1 alleles on Th1 and Th2 cytokine response to Mycobacterium tuberculosis antigens in pulmonary tuberculosis

The influence of human leukocyte antigens (HLA) on the immune response is well established. We investigated the regulatory role of HLA-DRB1 alleles on cytokine response to live M. tuberculosis and its culture filtrate antigen (CFA) in normal healthy subjects (NHS) and pulmonary tuberculosis (PTB) patients. Th1 (IFN-gamma and IL-12p40), Th2 (IL-4 and IL-5), pro-inflammatory (IL-6 and IL-8) and anti-inflammatory (TGF-beta and IL-10) cytokines were measured by ELISA in 72-h-old peripheral blood mononuclear cell culture supernatants from 58 NHS and 48 PTB patients. HLA-DRB1 genotyping was carried out by polymerase chain reaction and dot-blot hybridization with biotinylated sequence-specific oligonucleotide probes and detection by chemiluminescence. In response to live M. tuberculosis and CFA, significantly increased levels of IL-6, IL-8 and TGF-beta and decreased IFN-gamma, IL-12p40 and IL-10 were seen in PTB patients compared to NHS. We observed a significantly increased IFN-gamma response in HLA-DRB1*03-positive NHS (p=0.03) and decreased IFN-gamma response in HLA-DRB1*15-positive patients (p=0.04) than respective allele-negative individuals. An increased level of IL-12p40 in DRB1*10 (p=0.02) and IL-10 in DRB1*12- (p=0.03) positive NHS and an increased level of IL-6 in DRB1*04- (p=0.02) positive patients were observed. The study suggests that HLA-DRB1 alleles differentially modulate the various cytokine responses to M. tuberculosis antigens, which may influence the cellular and humoral immune responses to M. tuberculosis infection in a susceptible host.

Relationship between HLA polymorphisms and gamma interferon and interleukin-10 cytokine production in healthy individuals after rubella vaccination

We studied the association between HLA alleles and rubella-specific gamma interferon (IFN-gamma) (Th1) and interleukin-10 (IL-10) (Th2) cytokine responses among 106 healthy children (ages, 14 to 17 years) previously immunized with two doses of rubella vaccine. Antibody titers and cytokine responses to rubella vaccination were not sex or age dependent. Several class I HLA-A (*0201, *2402, *6801) alleles were significantly associated with rubella vaccine-induced IFN-gamma secretion. Several class II HLA-DRB1 (*0101) and HLA-DQB1 (*0501) alleles were also suggestive of an association with IFN-gamma secretion. Alleles with potential associations with rubella-specific IL-10 production included HLA-A (*0201, *6801), HLA-B (*4901), and HLA-DRB1 (*1302). The class I A*0201 and A*6801 alleles were associated with both IFN-gamma and IL-10 secretion. These tentative associations need to be validated in larger studies with subjects of differing ethnicities. These results provide additional evidence that HLA genes may influence Th1- and Th2-specific cytokine response(s) following rubella immunization, which in turn can influence both cellular and humoral immune responses to rubella vaccination.

Comprehensive analysis of class I and class II HLA antigens and chronic hepatitis B virus infection

Following an acute hepatitis B virus (HBV) infection, clearance or persistence is determined in part by the vigor and breadth of the host immune response. Since the human leukocyte antigen system (HLA) is an integral component of the immune response, we hypothesized that the highly polymorphic HLA genes are key determinants of viral clearance. HLA class I and II genes were molecularly typed in 194 Caucasian individuals with viral persistence and 342 matched controls who had cleared the virus. A single class I allele, A*0301 (odds ratio [OR], 0.47; 95% confidence interval [CI], 0.30 to 0.72; P = 0.0005) was associated with viral clearance. The class II allele DRB1*1302 was also associated with clearance (OR, 0.42; 95% CI, 0.19 to 0.93; P = 0.03), but its significance decreased in a multivariate model that included other alleles associated with disease outcome as covariates. B*08 was associated with viral persistence both independently (OR, 1.59; 95% CI, 1.04 to 2.43; P = 0.03) and as part of the conserved Caucasian haplotype A*01-B*08-DRB1*03. The B*44-Cw*1601 (OR, 2.23; 95% CI, 1.13 to 4.42; P = 0.02) and B*44-Cw*0501 (OR, 1.99; 95% CI, 1.22 to 3.24; P = 0.006) haplotypes were also associated with viral persistence. Interestingly, both the B*08 haplotype and DR7, which forms a haplotype with B*44-Cw*1601, have been associated with nonresponse to the HBV vaccine. The associations with class I alleles are consistent with a previously implicated role for CD8-mediated cytolytic-T-cell response in determining the outcome of an acute HBV infection.

Comprehensive analysis of class I and class II HLA antigens and chronic hepatitis B virus infection

Following an acute hepatitis B virus (HBV) infection, clearance or persistence is determined in part by the vigor and breadth of the host immune response. Since the human leukocyte antigen system (HLA) is an integral component of the immune response, we hypothesized that the highly polymorphic HLA genes are key determinants of viral clearance. HLA class I and II genes were molecularly typed in 194 Caucasian individuals with viral persistence and 342 matched controls who had cleared the virus. A single class I allele, A*0301 (odds ratio [OR], 0.47; 95% confidence interval [CI], 0.30 to 0.72; P = 0.0005) was associated with viral clearance. The class II allele DRB1*1302 was also associated with clearance (OR, 0.42; 95% CI, 0.19 to 0.93; P = 0.03), but its significance decreased in a multivariate model that included other alleles associated with disease outcome as covariates. B*08 was associated with viral persistence both independently (OR, 1.59; 95% CI, 1.04 to 2.43; P = 0.03) and as part of the conserved Caucasian haplotype A*01-B*08-DRB1*03. The B*44-Cw*1601 (OR, 2.23; 95% CI, 1.13 to 4.42; P = 0.02) and B*44-Cw*0501 (OR, 1.99; 95% CI, 1.22 to 3.24; P = 0.006) haplotypes were also associated with viral persistence. Interestingly, both the B*08 haplotype and DR7, which forms a haplotype with B*44-Cw*1601, have been associated with nonresponse to the HBV vaccine. The associations with class I alleles are consistent with a previously implicated role for CD8-mediated cytolytic-T-cell response in determining the outcome of an acute HBV infection.

Common HLA-B8-DR3 haplotype in Northern India is different from that found in Europe

The aim of this study was to determine whether a common diabetic haplotype, including human leukocyte antigen (HLA)-B8 and HLA-DR3, in Northern India is the same haplotype as the European HLA-B8-DR3 haplotype. DNA samples from Northern Indian subjects selected on the basis of HLA-B8 and HLA-DR3 were tested for microsatellite and single nucleotide polymorphism alleles throughout the major histocompatibility complex (MHC). It was found that the Indian samples represent a conserved haplotype in which all alleles were shared by Indian subjects with HLA-B8 and HLA-DR3, but were different to those that are characteristic of the European 8.1 ancestral haplotype. The Indian and European haplotypes share HLA-B*0801, HLA-DRB1*0301 and HLA-DQB1*02 but differ for subtypes of HLA-Cw*07 and HLA-DRB3 and all central MHC alleles tested. In contrast, Indian subjects selected on the basis of HLA-B58 ( 1-17) and HLA-DR3 shared the same alleles at other MHC loci as have been described in the common Chinese haplotype with HLA-B58/17 and HLA-DR3. A third haplotype, HLA-B50/21 and HLA-DR3, was also found to be highly conserved but shares little in common with the other two HLA-DR3-containing Indian haplotypes.

Associations of tumor necrosis factor alpha and HLA polymorphisms with adult dermatomyositis: implications for a unique pathogenesis

We recently reported that the -308A tumor necrosis factor alpha promoter polymorphism is associated with the photosensitive disorder subacute cutaneous lupus erythematosus and mediates an exaggerated tumor necrosis factor alpha response to ultraviolet B. We now sought to examine the association of this polymorphism with adult dermatomyositis, a photosensitive disease that exhibits some features in common with subacute cutaneous lupus erythematosus. Fifty adult patients with dermatomyositis and 239 healthy, race-matched controls were examined for the -308A tumor necrosis factor alpha polymorphism and the more common -308G allele. The frequency of the -308A allele was 0.27 in the entire dermatomyositis group, versus 0.14 in the controls (p = 0.003, chi2 2 x 2 table). Caucasians were the only racial/ethnic group in our study large enough to allow separate statistical analysis (47 dermatomyositis, 223 controls). The frequency of the -308A allele was 0.26 for dermatomyositis and 0.14 for controls (p = 0.014). Caucasians are known to exhibit a linkage disequilibrium between -308A and HLA-DR3, which we previously found to be significantly enhanced in subacute cutaneous lupus erythematosus patients. In contrast, we now found no increase in the association of -308A and HLA-DR3 in Caucasians with dermatomyositis compared to controls. Consistent with this observation, the association of these two genes in dermatomyositis was significantly less than we previously reported in Caucasians with subacute cutaneous lupus erythematosus (p = 0.016). We conclude that the tumor necrosis factor -308A polymorphism is associated with dermatomyositis, which suggests a pathophysiologic contribution from ultraviolet-induced production of tumor necrosis factor alpha, similar to subacute cutaneous lupus erythematosus. The differences in linkage with HLA-DR3, as well as several divergent clinical features, indicate that there are also fundamental mechanistic differences between dermatomyositis and subacute cutaneous lupus erythematosus.

Dissecting the genetic complexity of the association between human leukocyte antigens and rheumatoid arthritis

Rheumatoid arthritis (RA) is an inflammatory disease with a complex genetic component. An association between RA and the human leukocyte antigen (HLA) complex has long been observed in many different populations, and most studies have focused on a direct role for the HLA-DRB1 "shared epitope" in disease susceptibility. We have performed an extensive haplotype analysis, using 54 markers distributed across the entire HLA complex, in a set of 469 multicase families with RA. The results show that, in addition to associations with the DRB1 alleles, at least two additional genetic effects are present within the major histocompatibility complex. One of these lies within a 497-kb region in the central portion of the HLA complex, an interval that excludes DRB1. This genetic risk factor is present on a segment of a highly conserved ancestral A1-B8-DRB1*03 (8.1) haplotype. Additional risk genes may also be present in the HLA class I region in a subset of DRB1*0404 haplotypes. These data emphasize the importance of defining haplotypes when trying to understand the HLA associations with disease, and they clearly demonstrate that such associations with RA are complex and cannot be completely explained by the DRB1 locus.

Cutaneous lupus erythematosus: a review

This article will review and update information about the pathogenesis, clinical presentation, diagnosis, and treatment of cutaneous lupus erythematosus. Lupus erythematosus (LE) can present as a skin eruption, with or without systemic disease. Cutaneous LE is subdivided into chronic cutaneous LE, subacute cutaneous LE and acute LE. The prevalence of systemic lupus erythematosus (SLE) is 17-48/100,000 population worldwide. Skin disease is one of the most frequent clinical complaints of patients suffering from SLE. It has been found to occur in up to 70% of patients during the course of the disease. The most frequent mucocutaneous manifestations of SLE are malar rash (40%), alopecia (24%), and oral ulcers (19%). It has been suggested that risk factors that are more likely to signal transition of cutaneous into systemic LE are high ANA titers (> 1:320) and the presence of arthralgias. CLE patients who exhibit these symptoms should be monitored closely, since they may be at increased risk to develop SLE.

Cryptic determinants and promiscuous sequences on human acetylcholine receptor: HLA-dependent dichotomy in T-cell function

Experimental autoimmune myasthenia gravis can be induced in some strains of mice and rats by immunizing with acetylcholine receptor. Also, epidemiologic studies demonstrate an MHC linkage of myasthenia gravis in the man. In order to obtain direct experimental evidence for the influence of the genes of the MHC complex in the development of myasthenia gravis, we used mice transgenic to individual HLA molecules. We observed an increased susceptibility to the disease in HLA DQ8 transgenic mice compared to HLA DQ6 transgenic mice ( J. Immunol. 160:4169; 1998). These mice lacked endogenous mouse class II molecules. In the present study we mapped the cryptic and dominant sequences on the extra cellular region of human acetylcholine receptor. Although some epitopes (e.g., alpha11-30, alpha141-160, alpha171-190) were common between DQ8 and DQ6 transgenic mice, several others were disparately recognized. We also found a functional dichotomy in T cells from mice differing by one MHC molecule (HLA DQ8 or DQ6) when primed by sequences immunodominant in DQ8 and DQ6 tg mice. Differential disease manifestation in the two different HLA transgenic mice could be explained not only by differential recognition of peptides by these antigen presenting molecules, but also by the difference in the functional profile of T cells generated when primed by promiscuous sequence regions.

A genetically determined high setting of TNF-alpha influences immunologic parameters of HLA-B8,DR3 positive subjects: implications for autoimmunity

The 8.1 ancestral haplotype (AH) is a common Caucasoid haplotype carried by most people who type for HLA-B8,DR3. It seems unique in its association with a wide range of immunopathologic diseases. Healthy subjects bearing this haplotype demonstrate several alterations of immune response. This article will focus on the identification of the mechanism(s) of disease susceptibility of 8.1 AH. In 13 carriers of 8.1 AH, and 43 negative patients, enzyme immune assays serum levels of tumor necrosis factor (TNF)-alpha, soluble endothelial leukocyte adhesion molecule-1 (sELAM-1), cortisol, and interleukin(IL)-10 were determined. In addition, quantification of cytokine produced in vitro after mitogen stimulation was studied, and all subjects were genotyped for alleles at -592, -819, and -1082 nucleotides of IL-10 gene 5' flanking region, which is known to control IL-10 production. Results revealed that 8.1 AH is associated with a high in vivo and in vitro production of TNF-alpha, which in turn seems responsible for increased serum levels of sELAM-1, cortisol, and IL-10. On the contrary, in vitro production of IL-10 is not increased in these patients and there are no differences in allele promoter frequencies between the two groups that might explain the differences in IL-10 serum values. Thus, serum values seem to be the result of the effects of increased serum levels of TNF-alpha and cortisol. In conclusion, the increased spontaneous release of TNF-alpha, which modifies a certain number of immunologic parameters, may be the most characterizing feature of 8.1 AH. The consequent modification of the immunologic scenario might be involved in the predisposition to the impressive number of diseases and the changes in immune response observed in the patients studied.

Recipient HLA-DR3, tumour necrosis factor-alpha promoter allele-2 (tumour necrosis factor-2) and cytomegalovirus infection are interrelated risk factors for chronic rejection of liver grafts

BACKGROUND/AIMS

The tumour necrosis factor (TNF)-2 promoter allele, which elicits elevated expression of TNF-alpha, is in linkage disequilibrium with the extended haplotype HLA-A1-B8-DR3-DQ2. TNF-2 and HLA-DR3 have been implicated in renal and cardiac graft rejection and loss. Cytomegalovirus (CMV) infection has been associated with chronic allograft rejection. We examined the relationship between HLA-DR3, promoter allele TNF-2 and cytomegalovirus in relation to chronic rejection following liver transplantation.

METHODS

(i) Retrospective analysis of HLA-DR3 was performed in 307 liver transplant recipients and 283 donors. (ii) Prospective analysis of TNF-alpha promoter allele status, HLA-DR3 status and cytomegalovirus infection was assessed in 123 recipients.

RESULTS

(i) Retrospective analysis. Recipient HLA-DR3 (relative risk 1.9; 95% C.I. 1.01-3.58) was a risk factor for chronic rejection. (ii) Prospective analysis. Recipient HLA-DR3 was a risk factor for chronic rejection (relative risk 3.41; 95% C.I. 1.66-7.03) which was elevated further by superimposed CMV infection (relative risk 5.01; 95% C.I. 2-12.55). Recipient TNF-2 was associated with chronic rejection (relative risk 2.29; 95% C.I. 0.9-5.83) through linkage to HLA-DR3.

CONCLUSIONS

Recipient HLA-DR3, TNF-2 status and CMV infection were inter-related risk factors for chronic rejection of liver grafts.

Association of a promoter polymorphism of tumor necrosis factor-alpha with subacute cutaneous lupus erythematosus and distinct photoregulation of transcription

Ultraviolet irradiation stimulates keratinocytes and dermal fibroblasts to release cytokines involved in apoptosis and immunomodulation, such as tumor necrosis factor-alpha and interleukin-1alpha. Recent work has associated the -308A polymorphism of the human tumor necrosis factor-alpha promoter with systemic lupus erythematosus and adverse outcomes in several infectious diseases. To explore the role of this polymorphism in ultraviolet-induced disease, we used two approaches. First, we examined its prevalence in individuals with different ultraviolet sensitivity. Compared with healthy controls, there was a substantially increased prevalence of -308A in subacute cutaneous lupus erythematosus, an extremely photosensitive form of cutaneous lupus erythematosus, but not in discoid lupus erythematosus, a less photosensitive form. Next, to examine molecular regulation by tumor necrosis factor -308A, cultured 3T3 fibroblasts were transiently transfected with chloramphenicol acetyl transferase reporter constructs under the control of either -308A or the wild-type -308G promoter. Without added interleukin-1alpha the two constructs produced similar baseline chloramphenicol acetyl transferase activity and similar responses to ultraviolet. The responses to interleukin-1alpha, a photoinduced cytokine, were markedly different: interleukin-1alpha without ultraviolet produced a 15-fold increase in chloramphenicol acetyl transferase transcription from the -308A construct without affecting the wild-type -308G. Interleukin-1alpha plus ultraviolet B caused a remarkable 300-fold increase in -308A chloramphenicol acetyl transferase transcription over baseline, while increasing the wild type to <15% of this level. These results indicate a clear difference between the two promoters, including a striking synergy between ultraviolet B and added interleukin-1alpha in the induction of transcription by the tumor necrosis factor-alpha -308A promoter. Overall, our findings indicate a strong linkage between the -308A polymorphism and subacute systemic lupus erythematosus, which is likely to directly contribute to the photosensitivity of these patients.

Lymphocytes from H2 mice produce lower levels of several cytokines than congenic H2 or H2 mice

Inbred mice of congenic strains that differ only in their H2 haplotype were used to examine the effects of MHC genes on production of cytokines. Spleen and lymph node cells were stimulated with mitogens in vitro, and cytokine protein was assessed by ELISA and/or bioassays. Cells from H2b mice synthesized less IL-3, IL-4, IL-5, TNF and IL-10 (less clearly) than the equivalent cells from H2k or H2d mice. Production of IL-6 by H2b spleen and lymph node cells was lower than that by cells from H2d mice. In addition, lower lymphoproliferative responses were observed in lymph node cultures from H2b mice. These effects were evident in congenic B10 and BALB strains. B10 H2b mice stimulated in vivo with anti-CD3 had lower levels of IFN-gamma and IL-5 protein in their serum compared with equivalent H2k and H2d mice. Because class I- or II-mediated antigen presentation was not required in our model, an immunoregulatory gene in the central MHC is implicated. Preliminary studies of MHC recombinant mice suggested that the gene or genes responsible lie telomeric of IEbeta. Evidence that the H2b haplotype carries an immunoregulatory allele with a small but consistent effect on cytokine production warrants further investigation.

Influence of HLA-DR antigens on lymphocyte response to Mycobacterium tuberculosis culture filtrate antigens and mitogens in pulmonary tuberculosis

SETTING

Influence of HLA-DR antigens and lymphocyte responses in pulmonary TB patients.

OBJECTIVE

To elucidate the role of HLA-DR genes/gene products on lymphocyte responses to Mycobacterium tuberculosis antigens and mitogens, the present study was carried out in pulmonary tuberculosis during active and cured stage of the disease.

DESIGN

Serological determination of HLA-DR antigens was carried out in 50 active TB patients, 44 cured TB patients and 58 normal healthy control subjects. The influence of HLA-DR antigens on peripheral blood lymphocyte responses to M. tuberculosis culture filtrate antigens and mitogens such as phytohaemagglutinin (PHA) and concanavalin-A (Con-A) was studied in the patients as well as normal healthy control subjects.

RESULTS

Of all the DR antigens studied, patients (active TB and cured TB) with DR2 antigen showed an increased lymphocyte response (stimulation index) to a higher dose of antigenic (10 micrograms/ml) stimulation. A significantly lower lymphocyte response to antigen and mitogens was seen in HLA-DR3 positive normal healthy subjects than non-DR3 (DR3 negative) subjects.

CONCLUSION

The present study suggests that HLA-DR genes/gene products may be playing an immunoregulatory role in eliciting an immune response against M. tuberculosis antigens and mitogens induced lymphocyte response in pulmonary TB patients and normal healthy subjects.

Effects of stimulus and cell type on the expression of the -308 tumour necrosis factor promoter polymorphism

The authors have previously demonstrated that the tumour necrosis factor (TNF) -308 G/A polymorphism affects the binding of transcription factors. In transient transfection assays in PMA stimulated U937 monocytes and Jurkat T cells, the A-containing TNF2 promoter has a 2-3-fold greater transcriptional activity than the TNF1 promoter in the presence of the TNF 3'UTR. In this study it was found that a difference in TNF1 and TNF2 promoter activities was only observed in U937 and Jurkat cells, and not in Raji (B cell line), HeLa (epithelial carcinoma cell line), HepG2 (hepatoma cell line) or THP-1 (monocyte), suggesting cell-type specific transcription factors or modifications may be involved in the formation of the -308 protein/DNA complex. Physiological stimulators, TNF and interferon gamma (IFN-gamma) did not cause differential promoter activity between TNF1 and TNF2, but LPS did with only the TNF2 promoter/3'UTR construct being significantly responsive to lipopolysaccharide (LPS) in U937 cells. In U937 cells, the -308 polymorphism affected transcription following differentiation by phorbol myristate acetate (PMA), retinoic acid, PMA plus LPS and PMA plus retinoic acid with an increase in nuclear factor binding to both TNF1 and TNF2 in the -323 to -285 region being observed. The greatest difference between TNF2 and TNF1 promoter activities (5-fold) was observed following PMA plus retinoic acid treatment of transfected U937 cells for 48h. During this time, U937 differentiated into cells with a macrophage-like morphology. An understanding of the cell type and stimuli specific requirements for differential expression of the -308 polymorphism may help elucidate the role the TNF -308 polymorphism plays in diseases where elevated TNF levels are thought to be important.

The genetic basis for the association of the 8.1 ancestral haplotype (A1, B8, DR3) with multiple immunopathological diseases

An individual's major histocompatibility complex (MHC) ancestral haplotype (AH) is the clearest single determinant of susceptibility to MHC associated immunopathological disease, as it defines the alleles carried at all loci in the MHC. However, the direct effects of any of the 150-200 genes that constitute the MHC are difficult to determine since recombination only occurs at defined hotspots. This review concerns the 8.1 AH (HLA-A1, C7, B8, C4AQ0, C4B1, DR3, DQ2), which is carried by most Caucasians with HLA-B8. It is associated with accelerated human immunodeficiency virus (HIV) disease, and susceptibility to insulin-dependent diabetes mellitus (IDDM), systemic lupus erythematosus, dermatitis herpetiformis, common variable immunodeficiency and IgA deficiency, myasthenia gravis and several other conditions. We have mapped susceptibility genes for HIV, IDDM and myasthenia gravis to the central MHC between HLA-B and the tumour necrosis factor or complement genes. Here we consider which of the remaining 8.1-associated diseases are more closely associated with HLA-DR3 and/or DQ2. Several candidate genes in the central MHC have the potential to modulate immune or inflammatory responses in an antigen-independent manner, as is seen in studies of cultured cells from healthy carriers of the 8.1 AH. Hence these genes may act as a common co-factor in the diverse immunopathological conditions associated with the 8.1 AH.

Hypothesis: interleukin-5 production impairment can be a key point in the pathogenesis of the MHC-linked selective IgA deficiency

Selective IgA deficiency (IgA-D) is associated with the expression of some human leukocyte antigens (HLA) haplotypes and Major Hystocompatibility Complex (MHC) gene products have been suggested to be involved in the regulation of IgA synthesis. Recently, we have obtained evidences indicating that MHC influences the production of IgA and interleukin-5 (IL-5) both in humans and in mice. Lymphnode cells from pychril chloride (PC1) immunised BALB/c mice (bearing the H-2d haplotype) fail to produce IL-5 when stimulated in vitro with PC1 and this correlates with low antigen specific IgA production in vivo. In contrast using congenic BALB/k mice (bearing the H-2k haplotype) an high production both of IL-5 and of PC1-specific IgA is observed. Moreover, in vivo or in vitro administration of IL-5 to BALB/c mice was able to increase the production of antigen specific IgA. Similar evidences have been obtained by evaluation of the HLA influence on circulating immunoglobulin levels and interleukin production in normal HLA typed subjects. In fact HLA-B8, DR3 positive subjects show reduced level of serum IgA and their peripheral blood mononuclear cells stimulated with mitogen produce significantly reduced amounts of IL-5, IL-12, IL-2 and Interferon-gamma. We hypothesise that HLA-B8, DR3 associated IgA deficiency, known to be asymptomatic, can be due to a lack of subsequent signals, in particular of IL-5, involved in the late regulation of B cell differentiation. Preliminary evidences demonstrating that low amounts of human recombinant IL-5 are able to reconstitute IgA production by cells from HLA-B8, DR3 IgA-D subjects, seem to confirm this hypothesis.

Cytokines in juvenile chronic arthritis

Cytokines are important mediators of the immune response as well as the inflammatory response. Those concerned primarily with cell growth, differentiation and activation of cells within the immune system are called interleukins, of which there are now 18. Exposure to antigenic and environmental stimuli causes T cells to differentiate and polarise into Th1 or 2-like cells with different cytokine profiles, and requiring different cytokines for differentiation (IL-12 for Th1 and IL-4 for Th2). Homeostasis is usually restored as these cells are mutually inhibitory. Autoimmune diseases have been associated with a persistent imbalance with more Th1-like cells, which are thought to contribute to pathology. With regard to juvenile chronic arthritis (JCA), there is some preliminary evidence of this imbalance in the oligoarticular subgroup. Imbalance of pro-inflammatory cytokines, IL-1 and TNF with their natural inhibitors has also been shown to contribute to persistence of inflammation. In the case of JCA, there has been some evidence that these imbalances could account for some of the disease phenotypes. Furthermore, the tendency to imbalance is genetically determined.

Association of HLA B27 with benign clinical course of nephropathia epidemica caused by Puumala hantavirus

Both the severe course of nephropathia epidemica (NE) caused by Puumala hantavirus, and the fast progression of human immunodeficiency virus (HIV) disease, are associated with the HLA B8 DRB1*0301 haplotype. As HLA B27, on the contrary, is associated with the slow progression of HIV disease, we wanted to test whether the same is true for NE. Only six (8%) NE patients, half the figure expected, had the HLA B27 allele in 74 randomly selected hospital-treated patients. All six had a benign overall clinical course of NE; none had any severe complications, the severity of renal failure was also mild, and the treatment time at the hospital was half that needed for HLA B27- patients (P = 0.004). Patients who were HLA B27 had maximal blood leucocyte count > 10.000 x 10(9)/L (P = 0.020) more often, probably reflecting differences in immune response. Thus, similar HLA associations can be found in both HIV infection and NE caused by Puumala virus.

Cutaneous lupus mucinosis: a review of our cases and the possible pathogenesis

Cutaneous lupus mucinosis (CLM) is a rare variant of lupus erythematosus eruptions. Our 5 cases with CLM were reviewed. All were men with systemic lupus erythematosus (SLE). CLM occurred as asymptomatic cutaneous papules, nodules, or plaques on the trunk, upper and lower extremities, and face. Histopathology of CLM mainly revealed abundant mucin deposits among splayed collagen bundles throughout the dermis. However, some CLM lesions showed discoid lupus erythematosus-like epidermal and dermal changes and/or lupus profundus. Vasculitis was also revealed in the CLM lesions of 2 cases. The pathogenesis of CLM may be closely related to its two important features, the male preponderance and the association with SLE. Vasculopathy may also be involved in the development of CLM.

Non-specific airway hyperresponsiveness in mono-sensitive Sicilian patients with allergic rhinitis. Its relationship to total serum IgE levels and blood eosinophils during and out of the pollen season

BACKGROUND

Initial attempts to evaluate the association between allergic rhinitis and non-specific bronchial responsiveness has produced conflicting results. In fact, some studies showed a strong correlation and other failed to find an association. However, little is known about the effect of natural specific allergen exposure on the bronchial reactivity of mono-sensitive patients with rhinitis in the southern Mediterranean area, in relation to skin reactivity to allergens, total serum IgE levels and blood eosinophils.

OBJECTIVES

The significance of the association between allergic rhinitis, and abnormal airway responsiveness with regard to the pathogenesis of asthma is unclear. For this reason, we have studied non-specific bronchial hyperreactivity, in patients with seasonal allergic rhinitis, with reference to the responsible allergen. The aim of the study was to correlate the responsiveness to bronchoprovocation with methacholine in subjects a with allergic rhinitis during and out of the pollen season with total serum IgE and blood eosinophils.

METHODS

Fourty-nine non-smoking patients with clinical diagnosis of allergic rhinitis and mono-sensitive skin-prick tests to pollen allergens were enrolled in the study. Twenty patients suffered from seasonal rhinitis to Parietaria pollen, 15 patients to Gramineae pollen and 14 patients to Olea pollen. In all patients lung function measurements (assessed as response to methacholine), total serum IgE and blood eosinophil counts were measured during and out of the pollen season.

RESULTS

During pollen season, 16 out of 49 rhinitis patients demonstrated values of bronchial responsiveness measured as response to inhaled methacholine in the asthmatic range whereas out of the pollen season only eight patients were in the asthmatic range. By analysing the results with reference to the responsible allergen, during the pollen season 15 out of 16 patients were Parietaria-sensitive and out of the pollen season seven out of eight patients. Finally, in Parietaria-sensitive rhinitis bronchial responsiveness significantly correlated, during and out of the pollen season, with total serum IgE and with blood eosinophil counts.

CONCLUSIONS

Our results are consistent with the hypothesis that Parietaria is more important than Olea and Gramineae as a risk for developing non-specific bronchial hyperresponsiveness. On the whole, present observations provide further evidence that there is an interrelationship of allergen kind, total serum IgE, eosinophil and bronchial hyperresponsiveness suggesting that they may play a role in the development of bronchial asthma in rhinitis patients.

The cytokine network in juvenile chronic arthritis

This article is an overview of the cytokine network in patients with different types of juvenile chronic arthritis. The concept of the production of TH1-cell or TH2-cell differentiation as a result of cytokine production and the concept of the balance between proinflammatory and anti-inflammatory cytokines are explored. The balance of proinflammatory and anti-inflammatory cytokines could be altered as a result differences in the expression levels of a number of key cytokines and could be the critical events leading to chronic inflammation. Identifying molecular targets for intervention therapy to change the balance of the cytokine network is proposed.

Defective expression of CD95 (FAS/APO-1) molecule suggests apoptosis impairment of T and B cells in HLA-B8, DR3-positive individuals

Activation-induced apoptosis is one of the primary control mechanisms for the negative selection of an immune response, leading to maintenance of immune homeostasis and selective T cell deletion. The interaction between the surface molecule Fas and its ligand (FasL) has been proposed as a primary mechanism initiating T cell apoptosis. The T cell receptor modulates the expression and function of these molecules. Defects in the Fas/FasL apoptosis pathway have been shown to result in autoimmune disease in humans and in murine models. Because subjects carrying the HLA-B8, DR3 haplotype show a number of immune dysfunctions, including membrano-proliferative glomerulonephritis, systemic lupus erythematosus, Graves' disease, and others, we investigated Fas expression on T and B cells, and sensitivity to Fas-mediated apoptosis of activated T cells, to determine whether abnormalities of the Fas pathway might be associated with the development of autoimmune diseases in this group of individuals. Our findings show that B cells and resting T cells from HLA-B8+, DR3+ subjects express markedly reduced levels of Fas compared with those isolated from HLA-B8-, DR3+ individuals. Reduced levels of Fas were also evident on the surface of T cells from HLA-B8+, DR3+ subjects activated in vitro by stimulation with OKT3 and phytohemoagglutinin. Cycling T cells from these subjects, evaluated for apoptotic nuclei by flow cytometry after incubation with a cytolytic anti-Fas mAb, showed a significantly lower percentage of Fas-mediated apoptosis than did those from HLA-B8-, DR3- individuals. Normal levels of apoptosis were restored after exposure to a synthetic ceramide analog (C2). Further elucidation of the interaction of these molecules in autoimmune diseases may lead to better understanding of the pathogenesis of these disorders.

HLA-B8,DR3 haplotype affects lymphocyte blood levels

The number of lymphocytes in the blood is constant, pointing to an effective control of circulating lymphocyte values. The mechanisms of this regulation are uncertain, although it is likely that the number of blood lymphocytes is conditioned by hormones, homing factors and cytokines whose production is at least partly restrained by genetic factors. Particularly genetic factors linked to major histocompatibility complex (MHC) appear to be involved. In human beings a decreased number of blood lymphocytes has been described in healthy subjects carrying the Human Leucocyte Antigens (HLA) haplotype HLA-B8,DR3. In the present study, to inquire into the mechanisms of this lymphocyte decreased number, we have performed an analysis of blood subset values in these subjects. When the absolute values of lymphocytes were analysed according to HLA phenotype, HLA-B8,DR3 positive subjects (N = 26) displayed significantly lower values as compared to HLA-B8,DR3 negative ones (N = 282). The analysis of lymphocyte subpopulations performed by flow cytometry in 72 subjects did not show significant changes in lymphocyte subset percentages between HLA-B8,DR3 positive subjects and negative ones. Thus, the decrease of circulating lymphocytes seems to be due to a reduction of cell number affecting all lymphocyte subsets rather than a single cell subpopulation. The analysis of in vitro spontaneous apoptosis performed by flow cytometry in a smaller sample of subjects showed a significant increase of spontaneous apoptosis in lymphocytes from HLA-B8,DR3 positive individuals suggesting a possible explanation for the deviation from normal lymphocyte count observed in these subjects. However it is intriguing that a decreased number of blood lymphocytes can be observed in healthy HLA-B8,DR3 positive subjects but also in autoimmune diseases linked to this haplotype like systemic lupus erythematosus and insulin-dependent diabetes. Furthermore, in our opinion, this finding is to be kept in mind in evaluating hematological parameters in healthy subjects.

The cytokine network in juvenile chronic arthritis

This is a brief overview of the cytokine network within juvenile chronic arthritis, introducing the concept of the production of T-helper 1 (TH-1) or TH2-cell differentiation as a result of cytokine production, as well as the concept of the balance between pro- and anti-inflammatory cytokines. The balance of TH1 and TH2 cells of pro- and anti-inflammatory cytokines could be altered as a result of genetic differences in the expression levels of a number of key cytokines and may be the critical events leading to chronic inflammation. Finally, the importance of identifying molecular targets for intervention therapy to change the balance of the cytokine network is proposed.

The -308 tumor necrosis factor-alpha promoter polymorphism effects transcription

Since the tumor necrosis factor alpha (TNF-alpha) gene was found to be located in the central major histocompatibility complex (MHC) there has been much speculation concerning a genetic association between particular TNF alleles and disease susceptibility. A relationship between the MHC haplotype A1, B8, DR3, TNF-alpha expression levels and susceptibility to autoimmune disease has been suggested by several groups. The identification of the -308 polymorphism and its association with the HLA A1, B8, DR3 haplotype have led to speculation that the polymorphism may play a role in the altered expression of TNF-alpha. We have demonstrated that the region (-323 to -285) encompassing -308 in the TNF2 allele binds nuclear factors differently to the same region in the promoter of the more common TNF1 allele. The G/A -308 polymorphism affected the affinity of factor binding and resulted in a factor binding to TNF2 but not TNF1. The observed differential binding was shown to be functional, with the 38bp region from TNF2 causing a two-fold greater activity of a heterologous promoter over that due to the same region in TNF1. To further substantiate the functional consequences of the TNF-alpha -308 polymorphism, we analysed both allelic forms of the TNF-alpha promoter region (-993 to +110) in a transient transfection assay, using luciferase as a reporter gene. The results showed that when present with the 3'UTR the -308A allelic form gave a two-fold greater level of transcription than the 308G form in PMA-stimulated Jurkat and U937 cells. This suggests that the -308 G/A polymorphism may play a role in the altered TNF-alpha gene expression observed in individuals with the HLA A1, B8, DR3 haplotype.

Major histocompatibility complex regulation of cytokine production

This review describes the phenomenon of the major histocompatibility complex (MHC) control of cytokine production both in experimental animals and in humans. H-2 (mouse MHC) regulates which type of cytokine is selectively produced in response to the hapten trinitrophenyl (TNP). T cells from TNP-immune H-2k mice produce interferon-gamma (IFN-gamma), interleukin-2 (IL-2), IL-3, IL-5, tumor necrosis factor-alpha (TNF-alpha), IL-10, and very low levels of IL-4 on reexposure to the specific antigen in vitro. By contrast, T cells from H-2d mice produce IL-3, TNF-alpha, IL-10, and IL-4 but very low levels of IL-2, IL-5 and IFN-gamma. As MHC-congenic matched strains (BALB/k and BALB/c) are used, this makes it unlikely that non-MHC genes influence the class of response observed. A similar pattern of haplotype regulation of cytokine production is observed in humans. In fact, peripheral blood mononuclear cells from HLA-B8,DR3-positive and negative individuals differ in their ability to produce IL-2, IL-5, and IFN-gamma on stimulation with the mitogen phytohemagglutinin while producing similar amounts of IL-4, IL-6, and IL-10. The following main considerations emerge from these observations. The MHC/peptide complex generated after antigen immunization, indicates which class of cytokine production is preferentially induced and, therefore, the outcome of the immune response. Furthermore, MHC genotype may affect cytokine production (and then immune responses) by completely different mechanism(s), that is, by an antigen-nonspecific control that does not depend on the ability of MHC molecules to bind in different ways the different peptides. Accurate control of the functional repertoire of an immune response is a critical parameter in response to infections as well as in immunopathology. MHC control of the class of the immune response at the level of cytokine production is a sophisticated way in which this occurs. This control might be involved in adaptive immune responses to infections as well as in immunopathology.

In vitro T cell activation in elderly individuals: failure in CD69 and CD71 expression

A large number of T cell dysfunctions have been observed in the elderly. The most widely observed is the inability of these cells to proliferate at a level comparable to T cells from young individuals after stimulation by mitogens. To better characterize T cell impairment, we have focused on the in vitro T cell activation, analyzing by flow cytometry the activation molecules CD69 and CD71 on mitogen-stimulated lymphocytes from young and elderly subjects. The results show that the percentages of CD69+ and CD71 + T cells were significantly decreased in cultures from elderly subjects when compared to values obtained culturing cells from young individuals. The differences observed seem not due to differences in CD4 and CD8 rates in the "old' cells that underwent activation, since, following activation, the pattern of CD4 and CD8 phenotypes was the same in both groups of subjects. Signals from CD69 are relevant in controlling cytokine gene expression because its stimulation leads to interleukin-2 production and increases its receptor expression. The interaction of this cytokine with its cellular receptor is an essential requirement for T lymphocytes to express CD71 and to start proliferation. Thus, a key role in the age-associated impairment of T cell activation could be played by an ineffective modulation of CD69 expression suggesting a defect in the signal transduction pathway of the T cell receptor-CD3 complex in elderly.

Cytokine production pathway in the elderly

It is well known that aging is associated with various alterations in lymphoid cell functions, particularly with a progressive decline in immune responsiveness to exogenous antigens and increasing incidence of autoimmune phenomena. Many studies have been focused on the mechanisms of the immunologic features of aging. this review describes our results of studies performed to determine the influence of age on the capacity to produce interleukin-2 (IL-2), interferon-gamma (IFN-gamma), interleukin-4 (IL-4), interleukin-t (IL-5), interleukin-6 (IL-6) and tumor necrosis factor (TNF). Mitogen-stimulated cultures of mononuclear cells (MNC) from human beings were assessed for cytokine-producing capacity. A significant decrease in IFN-gamma and IL-2 production by MNC cultures from elderly individuals was observed. No significant difference was instead observed between cultures from elderly individuals and those from young ones as regards TNF-alpha, IL-4 and IL-6 production. Mitogen or antigen-stimulated cultures of MNC from aged mice also displayed a significant decrease in IFN-gamma and IL-2 production as well as TNF-beta. Instead IL-4 and IL-5 production significantly increased in these cultures. We suggest that this imbalanced cytokine production may well account for the pattern of immune response which may be observed in the elderly, i.e. a normal or increased humoral response (including autoimmune responses) in face of a low T cell immune responsiveness.

Major histocompatibility complex class II DR alleles DRB1*1501 and those encoding HLA-DR13 are preferentially associated with a diminution in maternally transmitted human immunodeficiency virus 1 infection in different ethnic groups: determination by an automated sequence-based typing method

Transmission of human immunodeficiency virus 1 (HIV-1) from an infected women to her offspring during gestation and delivery was found to be influenced by the infant's major histocompatibility complex class II DRB1 alleles. Forty-six HIV-infected infants and 63 seroreverting infants, born with passively acquired anti-HIV antibodies but not becoming detectably infected, were typed by an automated nucleotide-sequence-based technique that uses low-resolution PCR to select either the simpler Taq or the more demanding T7 sequencing chemistry. One or more DR13 alleles, including DRB1*1301, 1302, and 1303, were found in 31.7% of seroreverting infants and 15.2% of those becoming HIV-infected [OR (odds ratio) = 2.6 (95% confidence interval 1.0-6.8); P = 0.048]. This association was influenced by ethnicity, being seen more strongly among the 80 Black and Hispanic children [OR = 4.3 (1.2-16.4); P = 0.023], with the most pronounced effect among Black infants where 7 of 24 seroreverters inherited these alleles with none among 12 HIV-infected infants (Haldane OR = 12.3; P = 0.037). The previously recognized association of DR13 alleles with some situations of long-term nonprogression of HIV suggests that similar mechanisms may regulate both the occurrence of infection and disease progression after infection. Upon examining for residual associations, only only the DR2 allele DRB1*1501 was associated with seroreversion in Caucasoid infants (OR = 24; P = 0.004). Among Caucasoids the DRB1*03011 allele was positively associated with the occurrence of HIV infection (P = 0.03).

In vitro impairment of interleukin-5 production in HLA-B8, DR3-positive individuals implications for immunoglobulin A synthesis dysfunction

Healthy subjects carrying the HLA-B8,DR3 haplotype may show a large number of immune dysfunctions. Concerning T-cell dysfunctions, the most intriguing is a defect of the early phases of T-cell activation, responsible for the impairment of in vitro mitogen-stimulated cytokine production. Regarding B-cell dysfunctions, one the most fascinating topics is the association between this haplotype and IgA deficiency in healthy blood donors. Accordingly, HLA-B8,DR3-positive healthy subjects show significantly lower values of serum IgA than HLA-B8,DR3-negative ones. Because IL-5 is a stimulating factor for the secretion of IgA by committed B cells, we have analyzed the in vitro mitogen-stimulated IL-5 production by MNCs from healthy HLA-B8,DR3-positive individuals to study whether they display an impaired production of IL-5. The results clearly demonstrate that MNCs from HLA-B8,DR3-positive individuals display significant reduction of IL-5 production, suggesting that IgA synthesis dysregulation observed in HLA-B8,DR3-positive subjects could be due to an impairment of IL-5 production.

T-cell activation in HLA-B8, DR3-positive individuals. Early antigen expression defect in vitro

The HLA-B8, DR3 haplotype is overrepresented in several autoimmune diseases, implying that genes predisposing to these disorders are linked to this haplotype. In the patients affected by these diseases, as well as in healthy HLA-B8, DR3 individuals, various dysfunctions reflecting an impairment of T-cell activation have been found. To better characterize T-cell impairment of HLA-B8, DR3-positive healthy individuals, we analyzed the surface expression of early (CD69) and late (CD71) activation phenotypes. MNC cultures were stimulated with PHA and used for T-cell phenotyping by flow cytometry analysis. The results showed that the percentage of CD69+ T cells was significantly decreased in MNC from HLA-B8, DR3+ subjects. This defect was detected in cell cultures from all subjects studied, but it attained significance only in females in the early hours after stimulation. The difference in CD69 expression between HLA-B8, DR3-positive individuals and -negative ones was not due to differences in CD4 and CD8 ratios in the HLA-B8, DR3 cells that underwent activation, as following activation the pattern of CD4 and CD8 antigen expression was the same in both groups of subjects. Concerning the late antigen CD71, no significant difference in percentage was observed between T lymphocytes from HLA-B8, DR3+ and HLA-B8, DR3- subjects at all the times studied. The analysis of the requirements for CD69 expression has suggested that sustained PKC activation and an increase of intracellular CA2+ could be responsible for TCR/CD3-mediated CD69 induction. Thus, present data suggest a defect in the signal transduction pathway of the TCR/CD3 complex.(ABSTRACT TRUNCATED AT 250 WORDS)