Major histocompatibility complex regulation of cytokine production

An attenuated multiple genetic mutant of Mycoplasma pneumoniae imparts good immuno-protection against M. pneumoniae pneumonia in BALB/c mice

Mycoplasma pneumoniae (M. pneumoniae) is the causative agent of both upper and lower respiratory infections that can lead to pneumonia, extrapulmonary complications and devastating sequela. With the increasing rate of macrolide-resistant strains, the severe clinical consequence of refractory mycoplasma pneumonia in children health calls for the need of vaccine research for this pathogen. In this report, the immunomodulatory effectiveness of a live attenuated M. pneumoniae vaccine was evaluated. The vaccine strain was a mutant strain of M. pneumoniae, MUT129, obtained after multiple passages of M129 strain in PPLO broth. The SNP/InDel detection results showed that mutations were present in genes encoding the adhesion organelle-associated proteins and lipoproteins of M. pneumoniae MUT129. Upon intranasal challenge of BALB/c mice with 1 × 10⁷ CFU of MUT129, there were very small amount of Mycoplasma antigens and almost no M. pneumoniae present in the lung tissues of BALB/c mice. Besides, there was almost no inflammatory cell infiltration in the lung tissue. Results of the M. pneumoniae challenge study showed that mice immunized with MUT129 presented with less inflammation, lower detectable number of M. pneumoniae in the lungs when compared with the unimmunized mice. These results indicated that the live attenuated vaccine can efficiently prevent the proliferation of M. pneumonia in the lungs, reduce but not completely prevent the pulmonary inflammatory response.

HLA-A Locus is Associated With Sepsis and Septic Shock After Traumatic Injury

OBJECTIVE

Determine whether variation in the HLA region is associated with the development of post-traumatic sepsis and septic shock.

BACKGROUND

Sepsis-related deaths remain a major source of mortality after traumatic injury. Genetic characteristics may contribute to susceptibility to adverse outcomes including sepsis and septic shock. Recent advances in next-generation sequencing technology now allow comprehensive genotyping of the HLA region.

METHODS

White adult trauma patients requiring more than 2 days of mechanical ventilation underwent HLA genotyping, and were followed for the development of sepsis and septic shock. Odds ratios (OR) for the associations between our outcomes and HLA variants were estimated, a correction for multiple comparisons was applied, and significant variants were included in regression models adjusting for potential confounders.

RESULTS

A total of 1184 patients were included. Patients were severely injured (median injury severity score 33); 33% developed sepsis, 6% septic shock, and in-hospital mortality was 14%. An amino acid variant (156Q) within the HLA-A peptide-binding groove was associated with greater odds of sepsis [OR 1.50, (1.18-1.89)]. HLA-A∗02:01 was associated with lower odds of septic shock [OR 0.52, (0.32-0.82)]. These associations remained significant after adjusting for potential confounders.

CONCLUSIONS

This is the first study to apply next-generation sequencing techniques to evaluate associations between immunogenetic factors and post-traumatic sepsis and septic shock. Associations with class I HLA variants are novel as they implicate adaptive immunity in post-traumatic sepsis. These findings are a step towards developing a panel of genetic markers assessing risk of infection-related complications as we move towards more personalized medicine.

Autoimmune diseases and 8.1 ancestral haplotype: An update

The aim of the present review is to provide an update of the current research into the pathogenesis of autoimmune diseases associated with 8.1 ancestral haplotype. This is a common Caucasoid haplotype carried by most people who type for HLA-B8, DR3. Numerous genetic studies reported that individuals with certain HLA alleles have a higher risk of specific autoimmune disorders than those without these alleles. However, much remains to be learned about the heritability of autoimmune conditions. Recently, progress and advances in the field of genome-wide-association studies have revolutionized the capacity to perform large, economically feasible, and statistically robust analyses of HLA within 8.1 ancestral haplotype, and understand its contribute to autoimmune events. In this paper, the characteristic features of this haplotype that might give rise to diverse autoimmune phenotypes are reviewed, focusing on the contribution of the HLA-DRB1 gene, the most polymorphic sequence within the HLA II region.

Clinical Role of Human Leukocyte Antigen in Health and Disease

Most of the genes in the major histocompatibility complex (MHC) region express high polymorphism that is fundamental for their function. The most important function of human leukocyte antigen (HLA) molecule is in the induction, regulation of immune responses and the selection of the T cell repertoire. A clinician's attention is normally drawn to a system only when it malfunctions. The HLA system is no exception in this regard, but in contrast to other systems, it also arouses interest when it functions well - too well, in fact. Population studies carried out over the last several decades have identified a long list of human diseases that are significantly more common among individuals that carry particular HLA alleles including inflammatory, autoimmune and malignant disorders. HLA-disease association is the name of this phenomenon, and the mechanism underlying is still a subject of hot debate. Social behaviours are affected by HLA genes and preference for HLA disparate mates may provide 'good genes' for an individual's offspring. Also, certain HLA genes may be associated with shorter life and others with longer lifespan, but the effects depend both on the genetic background and on the environmental conditions. The following is a general overview of the important functional aspects of HLA in health and diseases.

Anti-CMV-IgG positivity of donors is beneficial for alloHSCT recipients with respect to the better short-term immunological recovery and high level of CD4+CD25high lymphocytes

Hematopoietic stem cell transplantation from anti-cytomegalovirus immunoglobulin G (anti-CMV-IgG) positive donors facilitated immunological recovery post-transplant, which may indicate that chronic CMV infection has an effect on the immune system. This can be seen in the recipients after reconstitution with donor lymphocytes. We evaluated the composition of lymphocytes at hematologic recovery in 99 patients with hematologic malignancies post hematopoietic stem cell transplantation (HSCT). Anti-CMV-IgG seropositivity of the donor was associated with higher proportions of CD4+ (227.963 ± 304.858 × 106 vs. 102.050 ± 17.247 × 106 cells/L, p = 0.009) and CD4+CD25high (3.456 ± 0.436 × 106 vs. 1.589 ± 0.218 × 106 cells/L, p = 0.003) lymphocytes in the blood at hematologic recovery. The latter parameter exerted a diverse influence on the risk of acute graft-versus-host disease (GvHD) if low (1.483 ± 0.360 × 106 vs. 3.778 ± 0.484 × 106 cells/L, p < 0.001) and de novo chronic GvHD (cGvHD) if high (3.778 ± 0.780 × 106 vs. 2.042 ± 0.261 × 106 cells/L, p = 0.041). Higher values of CD4+ lymphocytes in patients who received transplants from anti-CMV-IgG-positive donors translated into a reduced demand for IgG support (23/63 vs. 19/33, p = 0.048), and these patients also exhibited reduced susceptibility to cytomegalovirus (CMV), Epstein-Barr virus (EBV) and/or human herpes 6 virus (HHV6) infection/reactivation (12/50 vs. 21/47, p = 0.032). Finally, high levels (³0.4%) of CD4+CD25high lymphocytes were significantly associated with better post-transplant survival (56% vs. 38%, four-year survival, p = 0.040). Donors who experience CMV infection/reactivation provide the recipients with lymphocytes, which readily reinforce the recovery of the transplanted patients' immune system.

Association between Human Leukocyte Antigens (HLA-A, -B, and -DR) and end-stage renal disease in Kuwaiti patients awaiting transplantation

The number of patients with end stage renal disease (ESRD) is increasing considerably worldwide. Human Leukocyte Antigens (HLAs) are relevant for the expression of many immunological diseases and contribute to the development of different nephropathies. Therefore, we aimed from the present work to investigate the possible association between the frequency of HLA-A, -B, and -DR antigens and ESRD in Kuwaiti patients awaiting renal transplant. HLA-A, -B, and -DR typing was performed by complement-dependent cytotoxicity (CDC) method for 334 patients with ESRD awaiting renal transplantation and 191 healthy controls. The frequency of HLA-B8 antigen was significantly higher in ESRD patients (OR = 2.62, p = 0.001, pc = 0.038), and the frequency of HLA-A28, HLA-DR11 antigens was significantly higher in healthy controls (OR 0.42, p = 0.0001; pc = 0.0021, and OR = 0.44, p = 0.0007, pc = 0.01 respectively). While the HLA-B8 antigen may be a susceptibility risk factor for development of ESRD, the HLA-A28, and HLA-DR11 antigens may be protective against development of ESRD in Kuwaiti population.

Sudden Bilateral Sensorineural Hearing Loss Associated with HLA A1-B8-DR3 Haplotype

Sudden sensorineural hearing loss may be present as a symptom in systemic autoimmune diseases or may occur as a primary disorder without another organ involvement (autoimmune inner ear disease). The diagnosis of autoimmune inner ear disease is still predicated on clinical features, and to date specific diagnostic tests are not available. We report a case of bilateral sudden hearing loss, tinnitus, intense rotatory vertigo, and nausea in a female patient in which the clinical manifestations, in addition to raised levels of circulating immune complexes, antithyroglobulin antibodies, and the presence of the HLA A1-B8-DR3 haplotype, allowed us to hypothesize an autoimmune inner ear disease. Cyclosporine-A immunosuppressive treatment in addition to steroids helped in hearing recovery that occurred progressively with normalization of the hearing function after a five-month treatment. Cyclosporine-A could be proposed as a therapeutic option in case of autoimmune inner ear disease allowing the suspension of corticosteroids that, at high dose, expose patients to potentially serious adverse events.

HLA-B8, DR3: a new risk factor for graft failure after renal transplantation in patients with underlying immunoglobulin A nephropathy

BACKGROUND

The HLA-B8, DR3 haplotype has been associated with high immune reactivity. In this study, we have tested whether this haplotype has differential effect on graft survival in patients with IgAN compared with control patients.

METHODS

From the Eurotransplant Registry we analyzed graft survival of 1207 recipients with IgAN and 7935 control patients with non-glomerular diseases. Death-censored graft loss according to the HLA-B8, DR3 haplotype was calculated with Kaplan-Meier analysis and Cox-regression model was used to correct for various risk factors.

RESULTS

The frequency of the HLA-B8, DR3 haplotype was significantly lower in IgAN patients compared with controls (10.3% vs. 15.4%, p < 0.001). Ten-year graft survival was identical in the control group with and without the HLA-B8, DR3 haplotype (71.1% and 70.2%, respectively), but significantly worse in IgAN patients carrying the HLA-B8, DR3 haplotype compared with patients without it (52.5% vs. 69.1%, respectively, p = 0.009). The risk of graft loss was increased by 66% (HR 1.6, 95% CI 1.14, 2.29) in IgAN with the HLA-B8, DR3 haplotype and independent of well-known risk factors.

CONCLUSIONS

We have identified a new risk factor for graft loss unique to patients with IgAN. This finding emphasizes the exclusive immune characteristics of IgAN patients after transplantation.

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.

Genetic Control of Immune Response in Carriers of the 8.1 Ancestral Haplotype: Correlation with Levels of IgG Subclasses: Its Relevance in the Pathogenesis of Autoimmune Diseases

Ancestral haplotype (AH) 8.1(HLA-A1, Cw7, B8, TNFAB*a2b3, TNFN*S, C2*C, Bf*s, C4A*Q0, C4B*1, DRB1*0301, DRB3*0101, DQA1*0501, DQB1*0201) seems to be associated with susceptibility to autoimmune diseases. Different mechanisms are probably involved in increasing autoimmunity, such as unbalanced cytokine production and the lack of C4A protein. So AH 8.1 modifies immune response in many ways. In this study we demonstrate that IgG2 serum levels were significantly lower in 8.1 AH carriers than in 8.1 AH non-carriers. On the contrary, as regards IgG1, IgG3, IgG4 serum levels, no significant differences were observed between the two groups. In AH 8.1 carriers low IgG2 levels might take to slower clearance of the infectious agent and hence to a lasting presence of it. The persistence of infectious antigens could determine an increased production of autoantibodies with a higher risk of cross-reactions.

Human leukocyte antigen and interleukin 2, 10 and 12p40 cytokine responses to measles: is there evidence of the HLA effect?

HLA class I and class II associations were examined in relation to measles virus-specific cytokine responses in 339 healthy children who had received two doses of live attenuated measles vaccine. Multivariate linear regression modeling analysis revealed suggestions of associations between the expression of DPA1*0201 (p=0.03) and DPA1*0202 (p=0.09) alleles and interleukin-2 (IL-2) cytokine production (global p-value 0.06). Importantly, cytokine production and DQB1 allele associations (global p-value 0.04) revealed that the alleles with the strongest association with IL-10 secretion were DQB1*0302 (p=0.02), DQB1*0303 (p=0.07) and DQB1*0502 (p=0.06). Measles-specific IL-10 secretion associations approached significance with DRB1 and DQA1 loci (both global p-values 0.08). Specifically, suggestive associations were found between DRB1*0701 (p=0.07), DRB1*1103 (p=0.06), DRB1*1302 (p=0.08), DRB1*1303 (p=0.06), DQA1*0101 (p=0.08), and DQA1*0201 (p=0.04) alleles and measles-induced IL-10 secretion. Further, suggestive association was observed between specific DQA1*0505 (p=0.002) alleles and measles-specific IL-12p40 secretion (global p-value 0.09) indicating that cytokine responses to measles antigens are predominantly influenced by HLA class II genes. We found no associations between any of the alleles of HLA A, B, and Cw loci and cytokine secretion. These novel findings suggest that HLA class II genes may influence the level of cytokine production in the adaptive immune responses to measles vaccine.

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.

Genetic Control of Immune Response in Carriers of Ancestral Haplotype 8.1: The Study of Chemotaxis

In all caucasian populations the association of an impressive number of autoimmune diseases with genes from the HLA-B8, DR3 haplotype that is part of the ancestral haplotype (AH) 8.1 HLA-A1, Cw7, B8, TNFAB*a2b3, TNFN*S, C2*C, Bf*s, C4A*Q0, C4B*1, DRB1*0301, DRB3*0101, DQA1*0501, DQB1*0201 has been reported by different research groups. This haplotype, which is more common in northern Europe, is also associated with a number of immune system dysfunctions in healthy subjects. Analyzing the data according to gender, some dysfunctions are observed in women but not in men, in agreement with the role of X-linked genes and/or estrogens in the development and progression of autoimmune diseases. It has been proposed that a small number of genes within the 8.1 AH modify immune responsiveness and hence affect multiple immunopathological diseases. In this article, we demonstrate that neutrophil chemotaxis is significantly decreased in carriers of this AH, suggesting that this impairment may also be related to the increased occurrence of autoimmune diseases in these individuals.

HLA alleles, IFN-gamma responses to HPV-11 E6, and disease severity in patients with recurrent respiratory papillomatosis

Recurrent respiratory papillomatosis (RRP) remains an immunologic enigma. Human papillomavirus (HPV) types 6 and 11 are the predominant HPV viruses that cause papilloma development. However, it is unclear why only a very small fraction of HPV-exposed individuals develop RRP. We performed high-resolution HLA class I and II genotyping on 70 randomly selected patients (56 Caucasians and 14 African-Americans) with RRP. We report, for the first time, an increased frequency of HLA-DRB1*0102 in Caucasian patients with RRP, suggesting that this allele predisposes individuals to RRP. Additionally, HLA-DRB1*0301, DQB1*0201, and DQB1*0202 alleles were selectively enriched in Caucasians with severe disease, suggesting that these alleles may regulate disease severity. In contrast, HLA-DQB1*0602 was more frequent in controls than in Caucasians with severe disease, suggesting a severity-sparing effect of this allele. Furthermore, both DQB1*0201 and DQB1*0202 were enriched, whereas DQB1*0602 was absent, in African-Americans. Interestingly, HLA-DRB1*0301 and DQB1*0201 correlated with reduced interferon-gamma expression in patients with RRP. Larger studies are needed to identify other class II major histocompatibility complex alleles that may influence disease predisposition, disease severity, or both, especially in African-American patients, to ultimately illuminate the regulatory effects of these alleles in the predisposition and severity of RRP.

The −174G/C polymorphism of IL-6 is useful to screen old subjects at risk for atherosclerosis or to reach successful ageing

High levels of IL-6 are coupled with impaired immune efficiency, morbidity and mortality in ageing. Elderly men with GG (C-) genotype in -174 locus of IL-6 promoter are disadvantaged for longevity due to higher IL-6 than CG or CC (C+) carriers. As IL-6 increases in atherosclerosis, the study of the polymorphism of IL-6 may be a useful tool in identifying old subjects at risk for atherosclerosis. Thus, we divided old men into C+ and C- genotypes. Natural killer (NK) cell cytotoxicity, IL-6, IL-10, TNF-alpha, MTmRNA and zinc ion bioavailability were also evaluated and compared with nonagenarians and old patients affected by carotid stenosis. Old C- patients display, other than elevated IL-6, higher IL-10, TNF-alpha and MTmRNA coupled with impaired NK cell cytotoxicity and lower zinc ion bioavailability than C+ patients. The same trend is observed in old subjects with C- phenotype. Nonagenarians with C+ genotype show less inflammation, low MTmRNA, satisfactory NK cell cytotoxicity and good zinc bioavailability than long-living individuals with C- genotype. A higher degree of bilateral carotid stenosis is observed in C- patients than in C+ patients (88 vs 52%). Therefore, C- genotype is coupled with chronic inflammation, impaired immune efficiency, low zinc ion bioavailability and high MTmRNA. As such, C- genotype is a risk factor for the appearance of severe atherosclerosis. Thus, the polymorphism of IL-6, together with the analysis of zinc turnover and immune parameters, is of a great clinical relevance in order to genetically identify old subjects at risk in developing severe atherosclerosis and, at the same time, to predict subjects predestined to successful ageing. As a consequence, more convenient therapies may be prepared for a complete recovery.

Hydrogen peroxide induced down-regulation of CD28 expression of Jurkat cells is associated with a change of site α-specific nuclear factor binding activity and the activation of caspase-3

CD28 is the requisite co-stimulatory molecule in the activation of T cells and in the generation of immune responses. But expression of CD28 declined and oxidants accumulated in the elderly. Although accumulation of reactive oxygen species (ROS) during senescence has been reported extensively, the effect of oxidants on CD28-expression remains totally unknown. In this study, we tried to address the molecular mechanism underlying the decrease in CD28-expression of Jurkat T cells cultured in H2O2. Our results indicate that H2O2 could partially block the expression of CD28. This correlates well with a change of nuclear protein binding activity to the motif of site alpha of the CD28 gene, while the site beta-binding activity remained unaltered. On the other hand, since caspase-3 is activated by H2O2, inhibitors of caspase-3 should increase the expression of CD28. What is more interesting is the fact that the site alpha-binding activity was mostly restored after caspase-3 inhibitors had being added. However, caspase-3 is not activated by caspase-8. Maybe it is activated by caspase-9, which is triggered by cytochrome c. We believe that the procaspase-3 is activated by ROS, and the active caspase-3 can induce the change of the site alpha-binding activity, causing a decrease in CD28 expression.

In vitro effects of fluticasone propionate on IL-13 production by mitogen-stimulated lymphocytes

BACKGROUND

Corticosteroid administration produces multiple immunomodulatory effects, including down-regulation of cytokine production by CD4 T lymphocytes. Fluticasone propionate (FP) (Glaxo Smith&Kline, Greenford, UK), a highly lipophilic topical corticosteroid, has been shown to be safe and effective in the treatment of asthma and of both seasonal and perennial rhinitis.

AIMS

To gain insight into the mechanisms of FP therapeutic effects, we evaluated interleukin (IL)-13 (a type 2 cytokine that seemingly plays a pivotal role in allergic mechanisms) production by mitogen-stimulated peripheral blood mononuclear cells (MNC) in vitro, treated or not with FP.

METHODS

MNC from 10 healthy subjects and 10 asthmatic atopic patients with Parietaria allergy were stimulated v/v with phytohaemagglutinin (PHA) (50 gamma/ml) or with complete medium alone as a control. Culture supernatants, in vitro treated or not with 10(-7) or 10(-8) M FP, were collected after 48 or 72 h incubation. IL-13 production was assessed by enzyme-linked immunosorbent assay. In random selected samples, after 4 or 24 h of cell cultures, RNA was extracted and IL-4 and IL-5 reverse transcriptase-polymerase chain reaction (RT-PCR) products analyzed.

RESULTS

At 48 h, there were no differences in IL-13 concentration in PHA-stimulated cultures between healthy subjects and asthmatic patients (93.6 +/- 18.9 versus 111.0 +/- 25.1 pg/ml). At 72 h, similar results were obtained (63.9 +/- 3.0 versus 73.3 +/- 2.5 pg/ml, respectively). At this time, however, IL-13 concentrations were significantly decreased versus 48 h both in asthmatics (p < 0.001) and in controls (p < 0.001). Treatment with 10(-7) M FP significantly reduced IL-13 production in healthy subjects and asthmatic patients both at 48 h (93.6 +/- 18.9 versus 50.50 +/- 10.6 pg/ml, p < 0.001, and 111.0 +/- 25.1 versus 59.3 +/- 13.6 pg/ml, p < 0.001, respectively) and at 72 h (63.9 +/- 9.6 versus 35.5 +/- 4.4 pg/ml, p < 0.001, and 73.3 +/- 8.0 versus 40.7 +/- 4.5 pg/ml, p < 0.001, respectively). Similar results were obtained with 10(-8) M FP at 48 and 72 h. Accordingly, evaluation of RT-PCR products from selected cell samples showed a FP dosage-dependent inhibition of IL-4 and IL-5 mRNA production both for healthy subjects and asthmatic patients.

CONCLUSIONS

FP in vitro impairs IL-13 production by PHA-stimulated MNC from asthmatic and control subjects. This strengthens previous suggestions that IL-13 inhibition by steroids may, at least in part, account for their therapeutic effects.

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.

HLA-B27-transfected (Salmonella permissive) and HLA-A2-transfected (Salmonella nonpermissive) human monocytic U937 cells differ in their production of cytokines

The cytokine secretion of the Salmonella-permissive, HLA-B27-positive U937 cells was examined, as it was previously shown that these cells kill Salmonella less efficiently than controls. Salmonella-permissive U937 cells showed upregulated production of interleukin 10 and to a lesser extent tumor necrosis factor alpha. HLA-B27-associated modulation of cytokine responses may have importance in the pathogenesis of reactive arthritis.

Pathogenesis of autoimmune diseases associated with 8.1 ancestral haplotype: effect of multiple gene interactions

Genetic studies have shown that individuals with certain HLA alleles have a higher risk of specific autoimmune disease than those without these alleles. Particularly, the association in all Caucasian populations of an impressive number of autoimmune diseases with genes from the HLA-B8,DR3 haplotype that is part of the ancestral haplotype (AH) 8.1 HLA-A1, Cw7, B8, TNFAB*a2b3, TNFN*S, C2*C, Bf*s, C4A*Q0, C4B*1, DRB1*0301, DRB3*0101, DQA1*0501, DQB1*0201 has been reported by different research groups. This haplotype, the more common one in northern Europe, is also associated in healthy subjects with a number of immune system dysfunctions. It has been proposed that a small number of genes within the 8.1 AH modify immune responsiveness and hence affect multiple immunopathological diseases. In this paper, the characteristic features of this haplotype that might give rise to these diverse conditions are reviewed, focusing on the role of multiple gene interactions in disease susceptibility of 8.1 AH.

Muromonab-CD3-induced neurotoxicity: report of two siblings, one of whom had subsequent cyclosporin-induced neurotoxicity

Muromonab-CD3 is widely used for immunosuppression in patients undergoing solid organ transplant. We report two siblings with oligomeganephronia and end-stage renal disease who developed encephalopathy and seizures from muromonab-CD3 following renal transplant. The first case is a 13-year-old girl who developed encephalopathy, seizure, and triparesis following renal transplant while muromonab-CD3 was used for immunosuppression. The second case was the 6-year-old sister of the first case, who also developed recurrent focal seizures while she was on muromonab-CD3 for renal transplant immunosuppression. In both cases, a sequential brain magnetic resonance image (MRI) showed progression of abnormalities from the cerebral cortex to the white matter. In the first case, the MRI normalized after muromonab-CD3 was discontinued. In the second case, the patient developed a leukoencephalopathy following cyclosporin administration. The pathophysiology of muromonab-CD3 encephalopathy is believed to be a disturbance to the blood-brain barrier mediated by cytokine release from lymphocyte stimulation by muromonab-CD3. Because the major histocompatibility complex genes are known to regulate cytokine responses, it is possible that the excessive production of cytokines that causes encephalopathy may occur in patients who share close major histocompatibility complex genes. Muromonab-CD3 in a patient whose sibling has developed cerebral complications from its use should be administered with caution. The second case suggests that muromonab-CD3 encephalopathy predisposes patients to develop cyclosporin neurotoxicity. Because the pathogenesis of muromonab-CD3 encephalopathy and cyclosporin-related cerebral complications are both potentially mediated through a disturbance of the blood-brain barrier, it is possible that one agent may predispose a patient to the complication of the other.

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.

Immunogenetics of longevity. Is major histocompatibility complex polymorphism relevant to the control of human longevity? A review of literature data

Literature data suggest that human longevity may be directly correlated with optimal functioning of the immune system. Therefore, it is likely that one of the genetic determinants of longevity resides in those polymorphisms for the immune system genes that regulate immune responses. Accordingly, studies performed on mice have suggested that the Major Histocompatibility Complex (MHC), known to control a variety of immune functions, is associated with the life span of the strains. In the last 25 years, a fair number of cross-sectional studies that searched for the role of HLA (the human MHC) genes on human longevity by comparing HLA antigen frequencies between groups of young and elderly persons have been published, but conflicting findings have been obtained. In fact, the same HLA antigens are increased in some studies, decreased in others and unchanged in others. On the whole, that could lead us to hypothesize that the observed age-related differences in the frequency of HLA antigens are due to bias. In our opinion, this hypothesis is real for most studies owing to major methodological problems. However, some studies that do not meet these biases have shown an association between longevity and some HLA-DR alleles or HLA-B8,DR3 haplotype, known to be involved in the antigen non-specific control of immune response. Thus, HLA studies in man may be interpreted to support suggestions derived from the studies on congenic mice on MHC effects on longevity. However, in mice the association may be by way of susceptibility to lymphomas whereas, in human beings, the effect on longevity is likely, via infectious disease susceptibility. Longevity is associated with positive or negative selection of alleles (or haplotypes) that respectively confer resistance or susceptibility to disease(s), via peptide presentation or via antigen non-specific control of the immune response.

Immunosenescence: a review

Aging involves the morphological and functional integrity of all organs, including the cellular and humoral immunological functions. The main alterations can be listed as follows: (i) Thymic involution resulting in the decreased number of lymphoid precursor T- and B-cells. (ii) Reduced proliferative capacity of T-cells; loss of lymphocyte subgroups as a consequence of the shortening of telomeres. (iii) Qualitative deficiency of B-lymphocytes with a reduced response to exogenous antigens. (iv) Compromised activity of the accessory cells, both directly by depressing the chemotactic and phagocytic responses, and indirectly by increasing the prostaglandin production which inhibit the proliferation of T-cells. (v) Alterations in the production and secretion of various cytokines. (vi) Other factors like the general physiological conditions, the nutritional state, psychological habit and various hormone levels.

HLA, aging, and longevity: a critical reappraisal

Despite a large number of studies, available data do not allow at present to reach definitive and clear conclusions on role of HLA on longevity, owing to major methodological problems, such as serological and molecular typing of different loci, insufficient sample sizes, different inclusion criteria and age cut-off, inappropriate mixing of data referred to people from 58 to over 100 years of age, inappropriate control matching, and neglected consideration of sex-related effects and the different genetic make-up of studied populations. However, within this confused scenario, some data emerge. First, two studies that do not fit the biases above discussed show that some HLA alleles are associated with longevity. However, some of these alleles may confer an increased risk to undergo a variety of diseases. Second, longevity may be associated with an increased homozygosity at HLA loci. Third, an intriguing association between longevity and the 8.1 ancestral haplotype (AH), which has been proven to be associated with a variety of immune dysfunctions and autoimmune diseases, apparently emerges. This association appears to be a sex-specific (males) longevity contributor, and it is particularly interesting, taking into account that a type 2 (early infancy) --> type 1 (adulthood) --> type 2 (aging) shift of cytokine profile occurs lifelong, and that individuals bearing this haplotype show a type 2 immune responsiveness (note that type 1 cytokines mainly enhance cellular responses, whereas type 2 cytokines predominantly enhance humoral responses). On the whole, the (sex specific) association of longevity with alleles or haplotypes of several genes related to risk factors for a variety of diseases (cardiovascular diseases, cancer), including HLA alleles and haplotypes, is not unexpected on the basis of previous studies on the genetics of longevity in centenarians. This association can be interpreted under the perspective of a well known evolutionary theory of aging (antagonistic pleiotropy). This theory predicts that the same gene (or allele or haplotype) can have different roles (positive or negative) in different periods of the life span. Thus, the 8.1 AH should exert a positive effect during the infancy and aging but not in adulthood, when, indeed it is associated to susceptibility to a variety of diseases.

HLA-A, B, Cw and DRB1, DRB3/4/5, DQB1, DPB1 frequencies in German immunoglobulin A-deficient individuals

HLA class I and II frequencies and haplotype frequencies were determined in 80 German immunoglobulin (Ig)A-deficient individuals and 157 healthy controls with normal IgA levels using serological and DNA typing methods. For several alleles, significant associations were found, which could be explained mainly in the context of a positive association with three different extended haplotypes (HLA-B*08:DRB1*0301: DQB1*0201, HLA-B*14:DRB1*0102:DQB1*0501 and HLA-B*44:DRB1*0701:DQB1*0202) and a negative association with a fourth haplotype (HLA-B*07:DRB1*1501:DQB1*0602). Furthermore, for the first time this study reports a positive association of IgA deficiency with DPB1 alleles. Homozygosity rate for the gene loci DRB1 and DQB1 was increased in IgA deficiency. Further analysis suggested a different pattern of HLA associations depending on the degree of IgA deficiency and the gender of the IgA-deficient individuals.

In vitro treatment with interleukin-2 normalizes type-1 cytokine production by lymphocytes from elderly

The term immunosenescence is taken to mean the deterioration of immune function seen in elderly, which is manifested in increased susceptibility to infectious diseases, neoplasias, and autoimmune diseases. It is only recently that we have begun to understand the cellular and molecular changes involved. Of special interest in this regard are observations of a decline in synthesis of Type-1 cytokines which predisposes to diminished cell mediated immunity. We have evaluated the production of type 1 cytokines in old and young donors either in presence or in absence of recombinant interleukin-2 (rIL-2). Lymphocytes were stimulated with plastic bound anti-CD3 and after 48 h the supernatants were harvested and stored at -70 degrees C until assay. Type 1 cytokine, i.e. IL-12 and interferon-gamma (IFN-gamma) production by anti-CD3 stimulated lymphocytes from old subjects was significantly reduced when compared to that from young ones. This impaired production was reversed by adding rIL-2 in the culture medium. In previous studies on aged subjects, we have been able to demonstrate that in vitro treatment with rIL-2 completely restores proliferative responses and partially rescues the increased apoptosis of T cell cultures. Present and previous results suggest that rIL-2 completely restores Type 1 responses by overcoming the well known costimulation deficit of aged lymphocytes.

Age-related changes in the expression of CD95 (APO1/FAS) on blood lymphocytes

Aging is associated with alterations of the immune system, thought to be related to an increased susceptibility to infectious diseases, and possibly to cancer and autoimmunity in the elderly. In the present paper we report data obtained on freshly collected blood from 148 healthy subjects of different ages (from cord blood to 102 years old). The subjects were divided into seven age classes (cord blood, 3-11 years, 15-39 years, 41-60 years, 61-74 years, 75-84 years, 85-102 years) and their lymphocyte subsets and the expression of the apoptosis-related molecule CD95 were evaluated. In respect of lymphocyte subsets, the major differences were found in the cord-blood samples compared with the oldest old groups. In the cord-blood group, the absolute number of all the lymphocyte subsets was enhanced, but in the oldest group, an increase of CD16+ lymphocytes was observed, whereas CD19+ lymphocytes, which progressively decrease with age, continue to decrease further in the very old. The data show that the expression of CD95 increases until age 74 years, whereas in the oldest old it tends to decrease again. The trend of CD95 expression seems to be related to the change of expression of CD95 on CD4+ lymphocytes, because the CD8+/CD95+ population rose steadily throughout the entire age range. The evaluation of CD95+/CD45R0+ lymphocytes shows similar results to those observed analyzing CD95 on total lymphocytes. Furthermore, a constant increase of CD95+/CD28+ and a related decline of CD28+ lymphocytes was observed in all age groups. These data suggest that the expression of CD95 on the different subsets of lymphocytes can be considered a good marker for studies of immunosenescence, because it may be predictive of successful aging, and can partially explain the change in lymphocytes subsets in elderly.

Granulocyte and natural killer activity in the elderly

The deterioration of the immune system in ageing, 'immunosenescence', is thought to contribute to increased morbidity and mortality from infections and possibly autoimmune diseases and cancer. The most profound changes involve effector and immunoregulatory T-cell functions. Immunosenescence appears also to be related to changes in non specific immunity as well. In the present study we have assessed superoxide production, chemotaxis and the expression of the apoptosis-related molecule APO1/Fas (CD95) on neutrophils (PMN) from young and old subjects. Furthermore, we have measured the basal natural killer (NK) activity of young and elderly subjects and we have compared the number of CD16+ cells found in these two groups. We observed a significant decrease age-related both of formation of O2- and chemotaxis whereas no significant correlation between age and the expression of CD95 on granulocyte membrane was demonstrated, suggesting that an increase age-related of CD95-linked apoptosis of PMN should be not an important determinant in the decreased PMN function. We also observed a significant correlation between age and NK activity. The decreased NK cell function was not due to a decreased number of NK cells in effector cell preparations since the number of CD16+ cells was significantly increased in old subjects. In conclusion, our results show that in the elderly there is also a deficit of the aspecific immunity that might play a role in the pathogenic mechanisms of the immunosenescence.

IL-12 Modulates Expression of Hypersensitivity Pneumonitis

Hypersensitivity pneumonitis (HP) is a granulomatous, inflammatory lung disease caused by inhalation of organic Ags, most commonly thermophilic actinomycetes. Only a minority of individuals exposed to these Ags develops disease, suggesting that host factors are important for the expression of HP. We compared the expression of HP in a sensitive strain of mice, C57BL/6, and in a resistant strain of mice, DBA/2. They were exposed to the thermophilic bacteria Saccharopolyspora rectivirgula (SR) or to saline alone for 3 consecutive days/week for 3 wk. After exposure to Ag, C57BL/6 mice, but not DBA/2 mice, developed granulomatous inflammation with an increase in lung index (lung weight). Both strains had similar amounts of Ag delivered to the lungs after intranasal installation, as determined with 14C-labeled Ag. Both also had similar increases in total bronchoalveolar cells after Ag exposure, but the C57BL/6 mice had more lymphocytes. Compared with the resistant strain, the sensitive strain had a significantly greater Ag-induced increase in IL-12 and IFN-γ gene expression. DBA/2 mice resembled sensitive, C57BL/6 mice if they received IL-12 augmentation therapy at the time of Ag exposure. These findings were not limited to lung, since both unstimulated and SR-stimulated spleen cells from C57BL/6 mice released significantly more IL-12 than cells from DBA/2 mice. However, spleen cells from DBA/2 mice made more IFN-γ when exposed to IL-12, than cells from C57BL/6 mice. These results suggest that the IL-12 response to Ag may modulate in part the expression of HP.

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.

Macrophages Induce Cellular Immunity by Activating Th1 Cell Responses and Suppressing Th2 Cell Responses

Differentiation of naive CD4+ T cells (Th0) into Th1 or Th2 cells determines whether antigen will raise a cellular or a humoral immune response. The maturation pathway chosen by the Th0 cell is often decisive for the outcome of disease and depends among others on the (co-)stimulatory attributes of the APC and the nature and abundance of cytokines provided by the APC and the microenvironment. In this study, we used macrophages, loaded ex vivo with antigen, for inciting Th0 activation and differentiation in vivo. The macrophages were derived from a clonal, immortalized population that both functionally and phenotypically expressed features characteristic of mature macrophages. Injection into syngeneic mice of IFN-γ-treated, Ag-loaded macrophages induced a primary T cell response, indicated by the occurrence of a proliferative response in vitro after restimulation of splenocytes with Ag. Analysis of the accompanying cytokine secretion revealed high numbers of IFN-γ-producing Th1 cells and only a few IL-4-secreting Th2 cells. This dominance of Th1 cells had functional implications, reflected in the high titer of Th1 cell-dependent IgG2 Abs and the absence of IgG1, characteristic of humoral immunity. Moreover, administration of Ag-loaded macrophages to mice with an ongoing Th1/Th2 response resulted in a complete suppression of IgG1 production, whereas IgG2 levels remained unaffected. These results demonstrate that macrophages exert APC activity in the organism, strongly skew primary responses to cellular immunity, and in addition suppress an already generated Th2-dependent humoral response, thus characterizing these cells as Th1-oriented APC.

Differentiation of mesencephalic progenitor cells into dopaminergic neurons by cytokines

Rat progenitor cells from the germinal region of the fetal mesencephalon were isolated and expanded in media containing the mitogen epidermal growth factor. These cells remained mitotically active (up to 8 months), were immunoreactive for the progenitor cell marker nestin, and were readily infected with the BAG alpha retrovirus. When incubated in complete media containing serum in poly-L-lysine-coated plates, these cells spontaneously converted to neurons and glia but rarely expressed the dopamine (DA) neuron phenotype. Nineteen different cytokines were screened for their ability to induce the DA phenotype and only interleukin (IL)-1 was found to induce the expression of the DA neuron marker tyrosine hydroxylase (TH). The addition of IL-1, IL-11, leukemia inhibitory factor (LIF), and glial cell line-derived neurotrophic factor (GDNF) were found to further increase the number of TH immunoreactive (TH-ir) cells. The addition of mesencephalic membrane fragments and striatal culture-conditioned media along with the cytokine mixture induced the expression of morphologically mature TH-ir cells that were also immunoreactive for dopa-decarboxylase, the DA transporter, and DA itself. The DA neuron cell counts were approximately 20-25% of the overall cell population and 50% of the neurofilament population. Astrocytes and oligodendrocytes were also present. These data suggest that hematopoietic cytokines participate in the development of the DA neuron phenotype. Parallels between the function of hematopoietic cytokines in bone marrow and the central nervous system may exist and be useful in understanding the factors which regulate the differentiation of neurons in the brain.