On the coupling of two models of the human immune response to an antigen

The development of mathematical models of the immune response allows a better understanding of the multifaceted mechanisms of the defense system. The main purpose of this work is to present a scheme for coupling distinct models of different scales and aspects of the immune system. As an example, we propose a new model where the local tissue inflammation processes are simulated with partial differential equations (PDEs) whereas a system of ordinary differential equations (ODEs) is used as a model for the systemic response. The simulation of distinct scenarios allows the analysis of the dynamics of various immune cells in the presence of an antigen. Preliminary results of this approach with a sensitivity analysis of the coupled model are shown but further validation is still required.

HLA-DPB1*0402 protects against type 1A diabetes autoimmunity in the highest risk DR3-DQB1*0201/DR4-DQB1*0302 DAISY population

OBJECTIVE

A major goal in genetic studies of type 1A diabetes is prediction of anti-islet autoimmunity and subsequent diabetes in the general population, as >85% of patients do not have a first-degree relative with type 1A diabetes. Given prior association studies, we hypothesized that the strongest candidates for enhancing diabetes risk among DR3-DQB1*0201/DR4-DQB1*0302 individuals would be alleles of DP and DRB1*04 subtypes and, in particular, the absence of reportedly protective alleles DPB1*0402 and/or DRB1*0403.

RESEARCH DESIGN AND METHODS

We genotyped 457 DR3-DQB1*0201/DR4-DQB1*0302 Diabetes Autoimmunity Study of the Young (DAISY) children (358 general population and 99 siblings/offspring of type 1 diabetic patients) at the DPB1, DQB1, and DRB1 loci using linear arrays of immobilized sequence-specific oligonucleotides, with direct sequencing to differentiate DRB1*04 subtypes.

RESULTS

By survival curve analysis of DAISY children, the risk of persistently expressing anti-islet autoantibodies is approximately 55% for relatives (children with a parent or sibling with type 1 diabetes) in the absence of these two protective alleles vs. 0% (P = 0.02) with either protective allele, and the risk is 20 vs. 2% (P = 0.004) for general population children. Even when the population analyzed is limited to DR3-DQB1*0201/DR4-DQB1*0302 children with DRB1*0401 (the most common DRB1*04 subtype), DPB1*0402 influences development of anti-islet autoantibodies.

CONCLUSIONS

The ability to identify a major group of general population newborns with a 20% risk of anti-islet autoimmunity should enhance both studies of the environmental determinants of type 1A diabetes and the design of trials for the primary prevention of anti-islet autoimmunity.

Functional genomics analyses of differential macaque peripheral blood mononuclear cell infections by human immunodeficiency virus-1 and simian immunodeficiency virus

The pathogenicity of the primate lentiviruses, human, and simian immunodeficiency viruses, is host-specific. Previous studies indicated that the highly pathogenic human lentivirus HIV-1 has markedly reduced pathogenicity compared to the pathogenic simian lentivirus SIV in pigtail macaques (Macaca nemestrina). We therefore hypothesized that the pigtail macaque peripheral blood mononuclear cells (mPBMCs) would respond differently to infections of HIV-1 and pathogenic SIV. To elucidate the cellular responses to the infections of HIV-1 and SIV, we infected mPBMC with these two viruses. Like infections in vivo, HIV-1 and SIV demonstrated distinct replication kinetics in mPBMCs, with HIV-1 replicating at significantly lower levels. Similarly, gene expression profiling facilitated by macaque-specific oligonucleotide microarrays also revealed distinct expression patterns of genes between the HIV-1- and SIV-infected mPBMCs; in particular, genes associated with the antigen presentation, T cell receptor, ERK/MAPK signaling, Wnt/beta-catenin signaling, and natural killer cell signaling pathways were differentially regulated between these two viruses. Most interestingly, despite the lower levels of replication, HIV-1 triggered a more robust regulation of immune response genes early after infection; the converse was true in SIV-infected mPBMCs. Our results therefore suggest that macaques may be controlling the infection of HIV-1 at an early stage through coordinated regulation of host defense pathways.

The Eighth Human Leucocyte Differentiation Antigen (HLDA8) Workshop: natural killer cell section report

Monoclonal antibodies submitted to the natural killer (NK) cell section of the Eighth International Workshop on Human Leucocyte Differentiation Antigens (HLDA8) comprised those to known clusters of differentiation (CD), those to well-characterised molecules without a CD nomenclature, and those to unknown molecules. From the HLDA8 workshop, the seven well-characterised molecules in the NK cell panel were assigned a CD classification. These were NKG2D (CD314), LAIR-1 (CD305), NKp46 (CD335), NKp44 (CD336), NKp30 (CD337), CRACC (CD319), and NKG2C (CD159c).

The pathogenesis of coeliac disease

Coeliac disease is a common condition and its prevalence in UK is now thought to be approximately 1:100. It is being diagnosed and treated more frequently as awareness at the primary care level has increased. Coeliac disease is a complex disorder and is frequently associated with other disease processes. The management of these patients needs to take on a holistic approach, whilst the physician needs to be aware of the rare complications. This article gives an up-to-date review of the literature written on the pathogenesis of coeliac disease. We have attempted to paint a picture from beginning to end, whilst clarifying the grey areas in between. General epidemiological factors are reviewed before looking at genetic risk factors. We assess the sensitivity and specificity of the investigative modalities available for clinical use and comment on optimum management of these patients thereafter. The future of coeliac disease looks promising for patients with several novel therapies on the horizon. Whilst further work is still needed to breed out the toxic epitopes from wheat, novel therapies may come from other areas such as the work aimed at restoring normal tolerance to gluten.

The pathogenesis of coeliac disease

Coeliac disease is a chronic enteropathy caused by intolerance to gluten proteins. The true prevalence of this condition is greater than previously thought, with increasing numbers of 'silent' cases being diagnosed. Untreated coeliac disease is associated with significant morbidity and increased mortality. There have been a number of advances in our understanding of the pathogenesis of coeliac disease, in particular the mechanisms whereby gluten epitopes are processed, become modified by tissue transglutaminase (tTG) and then interact with HLA restricted T cells. An improved understanding of the immune response to gluten is likely to lead to the development of novel strategies for the treatment of coeliac disease.

Patients with Goodpasture's disease have two normal COL4A3 alleles encoding the NC1 domain of the type IV collagen 3 chain

BACKGROUND

Goodpasture's disease (GP) is a rare but severe disease characterized by anti-glomerular basement membrane antibodies, rapidly progressive glomerulonephritis and lung haemorrhage. The autoantibodies are restricted to a narrow epitope region on the NC1 domain of the alpha 3 chain of type IV collagen. GP is strongly associated with major histocompatibility complex (MHC) allele HLA DRB1-15. Recent research, however, has failed to identify a T-cell epitope with molecular characteristics that explain the relationship between the MHC class II molecule and the autoantibody generation. We hypothesized that an as yet unidentified sequence variant in exons 48-52 of the COL4A3 gene that encodes the NC1 domain of the type IV collagen alpha 3 chain could generate a new peptide sequence that, through interaction with specific MHC class II molecules, would increase the risk of developing GP.

METHODS

All patients previously treated for GP at the Lund and Malmö University Hospitals, who were alive at the time of the study, were asked to participate. DNA was extracted from leukocytes and subjected to genomic tissue typing and sequencing of the COL4A3 gene exons 48-52.

RESULTS

All 15 patients in the study had a nucleotide sequence in the COL4A3 gene encoding a protein identical to GenBank entry NM_000091. HLA D allele distribution was in line with previous publications, showing a strong positive association between HLA DRB1-15, HLA DQB1-6 and GP (P<0.02). Of the 15 GP patients, 73% carried HLA DRB1-15 and 87% carried the HLA DQB1-6 antigen. Corresponding figures for the controls were 27 and 50%.

CONCLUSION

This study effectively falsifies the hypothesis that a minor alteration in the COL4A3 gene could be a major factor in the aetiology of GP. Scandinavian GP patients have an MHC distribution similar to that which has been described previously for Anglo-Saxon patients.

Human T cells that have been conditioned by the proteolytic activity of the major dust mite allergen Der p 1 trigger enhanced immunoglobulin E synthesis by B cells

BACKGROUND

We have previously demonstrated that the proteolytic activity of Der p 1 selectively cleaves human CD25, the 55 kDa alpha subunit of the IL-2 receptor. As a result of cleavage of surface CD25, peripheral blood T cells produce less IFN-gamma and more IL-4, thereby leading to progressive polarization of the T cells towards a Th2 cytokine profile. Therefore, these observations underline the potential role of the proteolytic activity of Der p 1 in creating a microenvironment conducive for IgE synthesis.

OBJECTIVE

To study the effect of T cells that have been conditioned by the proteolytic activity of Der p 1 on IgE synthesis by B cells.

METHODS

We have examined this concept in experiments whereby T cells that have been exposed to either proteolytically active or inactive Der p 1 were cocultured with autologous B cells and IgE antibody synthesis was monitored.

RESULTS

Here we demonstrate for the first time that coculturing T cells that have been in contact with proteolytically active Der p 1 with autologous B cells leads to augmentation of IgE antibody responses.

CONCLUSIONS

The proteolytic activity of Der p 1 conditions human T cells, which then become empowered to trigger enhanced IgE synthesis by B cells.

Associations between human leukocyte antigens and nonresponsiveness to influenza vaccine

Influenza remains a major cause of morbidity and mortality, particularly in at-risk groups where vaccination reduces complications of infection but is not universally protective. In order to determine whether human leukocyte antigen (HLA) class II polymorphisms modulate anti-influenza antibody responses to vaccination, a cohort of HLA-typed at-risk donors was investigated. The subjects were recruited from a single urban family practice. Hemagglutination-inhibition (HAI) titers were measured immediately before and 28 days after subunit vaccination. Nonresponsiveness was defined as failure to mount an HAI response to any component of the trivalent influenza vaccine. When the nonresponders and responders with HLA class II were compared, the nonresponder group had more HLA-DRB1*07-positive donors (13/32 vs. 6/41 responders; P=.016, Fisher's exact test) and fewer HLA-DQB1*0603-9/14-positive donors (2/32 vs. 14/41 responders; P=.0045). Thus, polymorphisms in HLA class II molecules appear to modulate antibody responses to influenza vaccination.

The role of Helicobacter pylori virulence factors in interleukin production by monocytic cells

Helicobacter pylori infection results in chronic gastritis, which is initiated by the release of cytokines like interleukin (IL)-12 and IL-8 from mononuclear cells, and IL-8 from gastric epithelial cells. The severity of gastritis is influenced both by host factors and by bacterial factors such as the Cag proteins and the vacuolating cytotoxin VacA. Amounts of IL-12 and IL-8 produced by monocytic THP-1 cells differed considerably between the eight H. pylori isolates tested, but in contrast to H. pylori-induced IL-8 production by gastric epithelial cells, did not correlate to the Cag and VacA types of the strains. Apparently, in addition to Cag and VacA, other bacterial factors determine the extent in which H. pylori induced IL production in monocytes.

The role of Helicobacter pylori virulence factors in interleukin production by monocytic cells

Helicobacter pylori infection results in chronic gastritis, which is initiated by the release of cytokines like interleukin (IL)-12 and IL-8 from mononuclear cells, and IL-8 from gastric epithelial cells. The severity of gastritis is influenced both by host factors and by bacterial factors such as the Cag proteins and the vacuolating cytotoxin VacA. Amounts of IL-12 and IL-8 produced by monocytic THP-1 cells differed considerably between the eight H. pylori isolates tested, but in contrast to H. pylori-induced IL-8 production by gastric epithelial cells, did not correlate to the Cag and VacA types of the strains. Apparently, in addition to Cag and VacA, other bacterial factors determine the extent in which H. pylori induced IL production in monocytes.

Inflammatory myositis in children, including differential diagnosis

Advances in dermatomyositis and the juvenile idiopathic inflammatory myopathies over the past year included the development of new possible disease activity markers. Further evidence that these markers correlate with disease activity will give clinicians tools necessary for assessment of patient response to therapy. Validated disease activity and outcome measures will also allow for assessment of efficacy of new therapies as well as new combinations of older therapies. Basic questions about risks and benefits of widely used therapies such as pulse intravenous methylprednisolone still need to be addressed. Some open-label and retrospective assessments of therapeutic strategies for idiopathic inflammatory myopathies were recently published. Finally, further delineation of the roles of genetics, environment and immunity in the pathogenesis and course of the juvenile idiopathic inflammatory myopathies continued this year.

Relationship between unexplained infertility and human leukocyte antigens and expression of circulating autogeneic and allogeneic antisperm antibodies

PURPOSE

The association between unexplained infertility, human leukocyte antigens (HLA) and expression of circulating antisperm antibodies was studied in 52 couples with unexplained infertility and 15 infertile and 9 fertile couples.

METHODOLOGY

Evaluation parameters included Terasaki's HLA microlymphocytotoxicity test, circulating antisperm antibodies using immunofluorescence technique.

RESULTS

Fifty-two couples (8.7%) out of 600 consecutive clinic attendants had unexplained infertility. Unexplained infertility was associated with circulating antisperm antibodies (22 versus 13 and 0% for men and 18.5 versus 13 and 0% for women). HLA class 1 B6 and B52 and Cw7 and HLA class 2 DR4 and DR6 and sharing of HLA B6, DR4 and DR6 were found more in couples with unexplained infertility. Combined expression of antisperm antibodies by couples, demonstrated more homozygosity for HLA B6 and DR4.

CONCLUSION

Homozygosity for these antigens, B6, DR4 and DR6, may enhance the expression of antisperm antibodies, and cause infertility.

HLA association with hepatitis C virus infection

Hepatitis is one of the most important infectious diseases in Thailand. The knowledge of host factors that influence the course of the disease is still limited. In this study, the HLA class I and class II phenotypes were analyzed in the 2 groups of HCV-infected Thai populations. The first group included 43 individuals with transient HCV infection (HCV antibody positive, HCV RNA PCR negative), and the second included 57 individuals with persistent chronic HCV infection (HCV antibody positive, PCR positive). HLA class I typing was performed by 2-stage microlymphocytotoxicity test, and HLA class II typing, by PCR-SSO. No significant difference in the frequencies of HLA-A and -B antigens was observed between the 2 groups of HCV-infected individuals. The frequency of DRB1*0301 and DQB1*0201 was significantly higher in the persistent-infection group than in the transient-infection group (Pc = 0.03, Pc = 0.04, respectively). In addition, DRB1*0701 and DQA1*0201 were significantly decreased in all the HCV-infected patients compared with levels in the normal controls (Pc = 0.003, Pc = 0.001, respectively). This study demonstrated that DRB1*0301 and DQB1*0201 are associated with persistent HCV infection, whereas DRB1*0701 and DQA*0201 are associated with protection against HCV infection.

Abundant empty class II MHC molecules on the surface of immature dendritic cells

A monoclonal antibody specific for the empty conformation of class II MHC molecules revealed the presence of abundant empty molecules on the surface of spleen- and bone marrow-derived dendritic cells (DC) among various types of antigen-presenting cells. The empty class II MHC molecules are developmentally regulated and expressed predominantly on immature DC. They can capture peptide antigens directly from the extracellular medium and present bound peptides to antigen-specific T lymphocytes. The ability of the empty cell-surface class II MHC proteins to bind peptides and present them to T cells without intracellular processing can serve to extend the spectrum of antigens able to be presented by DC, consistent with their role as sentinels in the immune system.

Immunizations for the immunocompromised child

Although immunocompromised children are unlikely to have optimal immune responses to vaccines, some will benefit from immunization. They should receive inactivated vaccines that are routinely recommended for immunocompetent children plus pneumococcal and influenza immunizations. Live viral and bacterial vaccines are contraindicated with the exception of MMR. It may be given to children infected with HIV who do not have severe immunosuppression. The timing of immunizations is generally the same for immunocompromised and normal children. However, the MMR schedule in children infected with HIV is accelerated, with 2 doses given 1 month apart. Susceptible children whose immunosuppression is related to a temporary condition should be vaccinated after immune dysfunction has resolved. The question of revacination for children infected with HIV who are receiving effective antiretroviral therapy is under investigation, but no specific recommendations are currently available.

The antigen-presenting environment in normal and human papillomavirus (HPV)-related premalignant cervical epithelium

The activation of HPV-specific T cells within the cervical microenvironment is likely to play an important part in the natural history of cervical intraepithelial neoplasia (CIN). The extent and the type of T cell activation will depend critically on the expression of MHC, costimulatory cell surface molecules and cytokines by keratinocytes and Langerhans cells within the cervical lesion. Expression of MHC class II (HLA-A-DR and -DQ), costimulatory/adhesion molecules (CD11a/18, CD50, CD54, CD58 and CD86) and cytokines (tumour necrosis factor-alpha (TNF-alpha) and IL-10) was therefore investigated by immunohistochemistry in normal squamous epithelium (n = 12), low-grade (n = 23) and high-grade (n = 18) squamous intraepithelial lesions of the cervix. CIN progression was associated with de novo expression of HLA-DR and CD54, and increased expression of CD58 by keratinocytes. However, significantly, there was no expression of any adhesion/costimulation molecule by epithelial Langerhans cells in any cervical biopsy studied. Furthermore, TNF-alpha, a potent activator of Langerhans cells, was expressed constitutively by basal keratinocytes in normal cervix (12+/12). but expression of this cytokine was absent in a number of CIN samples (20+/23 for low-grade, 12+/18 for high-grade CIN). Conversely, the suppressive cytokine IL-10 was absent in normal epithelium (0+/12), but was up-regulated in a number of CIN lesions (12+/23 for low-grade; 8+/18 for high-grade CIN). The restricted expression of costimulation/adhesion molecules and the nature of the cytokine microenvironment within the epithelium may act to limit effective immune responses in some CIN lesions.

Human leukocyte antigen-associated susceptibility to pulmonary tuberculosis: molecular analysis of class II alleles by DNA amplification and oligonucleotide hybridization in Mexican patients

BACKGROUND

Pulmonary tuberculosis (PTB) develops by a complex combination of environmental factors with genetic susceptibility. In this context, an association between human leukocyte antigens (HLAs) and tuberculosis has been examined in several populations, but results have been controversial.

DESIGN AND MEASUREMENTS

A prospective evaluation of class II HLA genotypes was completed by the polymerase chain reaction (PCR) sequence-specific primer technique and PCR sequence-specific oligonucleotide hybridization in a Mexican population.

SETTING

This study was conducted at the Clinical Service of Tuberculosis and the Department of Immunology, National Institute of Respiratory Diseases, Mexico City, Mexico.

PATIENTS

Four groups were examined: 95 healthy subjects; 50 nonimmunosuppressed PTB patients; 15 HIV-infected patients (stage IVc in the Centers for Disease Control and Prevention [CDC] classification system for AIDS) with PTB; and 37 HIV-infected patients in the asymptomatic stage (CDC stage II).

RESULTS

The frequencies of alleles DQA1*0101 (odds ratio [OR], 6.18; 95% confidence interval [CI], 2.38 to 16.08), DQB1*0501 (OR, 6.16; 95% CI, 2.44 to 17.71), and DRB1*1501 (OR, 7.92; 95% CI, 2.71 to 23.14) were significantly increased in nonimmunosuppressed patients with PTB when compared with healthy subjects. By contrast, frequencies of allele DQB1*0402 and antigens DR4 and DR8 were significantly decreased in patients with PTB. Additionally, a significantly higher frequency of the DRB1*1101 allele was found in HIV-positive subjects (OR, 6.67; 95% CI, 2.13 to 20.83).

CONCLUSION

The genetic influence associated with the HLA system appears to have an important role in the development of PTB, although this susceptibility may not be relevant in patients with severe immunodeficiency diseases such as AIDS.

Antigen specific and nonspecific modulation of the immune response by aminolevulinic acid based photodynamic therapy

Photosensitizers used normally in treating cancers have considerable potential for treatment of other diseases. One such photosensitizer is the endogenously synthesized photosensitizer protoporphyrin IX (PpIX). To better understand how protoporphyrin might be used in transplantation or in treating autoimmune diseases, information must be obtained on how the photosensitizer affects all immune cells. We used a combination of flow cytometry and in vitro activation assays (recall assays and mixed-lymphocyte reactions) to examine the effects of PpIX on the antigen specific component, lymphocytes and the non-antigen specific component, the macrophages/monocytes and dendritic cells of the immune system. Whereas, lymphocytes accumulate PpIX only when activated, both macrophages and dendritic cells accumulated PpIX immediately, without in vitro activation, as measured by flow cytometry. ALA-PDT (aminolevulenic acid-photodynamic therapy) treated adherent cells in the recall assay had a decreased capability to activate lymphocytes. By increasing the light dose in the recall assay, antigen primed lymphocytes were selectively eliminated from a population of cells. Stimulator cells in an MLR had a decreased stimulatory capacity following ALA-PDT treatment. Functional alterations are seen in both the antigen specific

T-cell recognition of mycobacterial GroES peptides in Thai leprosy patients and contacts

We report here the mapping of T-cell-stimulatory determinants of the GroES 10-kDa heat shock protein homologues from Mycobacterium leprae and Mycobacterium tuberculosis, which are known as major immunogens in mycobacterial infections. Peripheral blood mononuclear cells (PBMC) from treated tuberculoid leprosy or lepromatous leprosy patients and from healthy household or hospital staff contacts of the patients were cultured with 20 16-mer peptides covering the entire sequences of both M. leprae and M. tuberculosis GroES. The total number of recognized peptides was found to be the largest in family contacts, while responder frequencies to the individual tested peptides varied (5 to 80%) with specificity between the patient and contact groups. Proliferative responses to some peptides showed positive or negative associations of low statistical significance with DR and DQ alleles, though responses to most GroES peptides were genetically permissive. Notably, the sequence of the 25-40 peptide of M. leprae, but not that of M. tuberculosis, was more frequently stimulatory in tuberculoid leprosy patients than in either group of sensitized healthy contacts. This peptide bound to a number of HLA-DR molecules, of which HLA-DRB5*0101 had the strongest affinity. The epitope core binding to this allele was localized to the 29-to-37 sequence, and its key residue was localized to the M. leprae-specific glutamic acid at position 32. This epitope may be of interest for the development of a blood test- or skin test-based diagnostic reagent for tuberculoid leprosy, subject to further clinical evaluation in untreated patients.

[Narcolepsy in children--a diagnostic and therapeutic challenge]

Narcolepsy is a socially and psychologically disabling disease that most often develops in adolescence or early adulthood. In a number of studies about one-third of the patients had experienced the first symptoms before the age of 15. The diagnosis and subsequent treatment is usually not established until several years later, often ten to fifteen years after the appearance of the first symptoms. If unrecognized and untreated, narcolepsy may lead to serious psychological and social problems during childhood and early adulthood, which may in turn cause difficulties in social adjustment later in life. This stresses the importance of early diagnosis. The diagnosis is based on clinical and polysomnographic criteria. In children, however, the clinical symptoms and polysomnographic findings may be atypical, making it difficult to establish a definite diagnosis. Three patients, two five-year olds and one four and a half-year old, are presented to illustrate the problems and considerations which must be taken into account in the diagnosis and treatment of children with narcolepsy.

Graft-versus-leukemia effects in T lineage and B lineage acute lymphoblastic leukemia

T and B lineage ALL cells express different levels of HLA-class II antigens, which may serve as targets for graft-versus-host disease (GVHD) and graft-versus-leukemia (GVL). The object of this study was to determine whether GVL effects after HLA-identical sibling bone marrow transplantation differed in T and B lineage ALL. We studied 1132 patients with ALL of T lineage (n = 416) or of B lineage (cALLa+) (n = 716) transplanted in first (n = 605) or second (n = 527) remission with bone marrow from an HLA-identical sibling donor, between 1982 and 1992, and reported to the IBMTR by 165 teams. Cox proportional hazards regression models were used to determine the relative risk (RR) of relapse in patients with acute (grades II-IV) or chronic GVHD vs patients without GVHD. Acute and chronic GVHD were considered as time-dependent covariates. Patients transplanted in first and second remission were analyzed separately. GVHD decreased relapse risks to a similar extent in T and B lineage ALL. For first remission transplants, relative risks of relapse for patients with vs those without GVHD was 0.34 for T lineage ALL and 0.44 for B lineage ALL. Corresponding relative risks in second remission transplants were 0.54 and 0.61. This study confirms earlier findings of an antileukemia effect of GVHD in ALL. This effect was similar in T lineage and B lineage ALL, despite probable differences in HLA-class II antigen expression.

Bone marrow transplantation in major histocompatibility complex class II deficiency: a single-center study of 19 patients

Major histocompatibility complex (MHC) class II deficiency (bare lymphocyte syndrome) is a rare inborn error of the immune system characterized by impaired antigen presentation and combined immunodeficiency. It causes severe and unremitting infections leading to progressive liver and lung dysfunctions and death during childhood. As in other combined immunodeficiency disorders, bone marrow transplantation (BMT) is considered the treatment of choice for MHC class II deficiency. We analyzed the files of 19 patients who have undergone BMT in our center. Of the 7 patients who underwent HLA-identical BMT, 3 died in the immediate posttransplant period of severe viral infections, whereas the remaining 4 were cured, with recovery of normal immune functions. Of the 12 patients who underwent HLA-haplo-identical BMT, 3 were cured, 1 was improved by partial engraftment, 7 died of infectious complications due to graft failure or rejection, and 1 is still immunodeficient because of engraftment failure. A favorable outcome in the HLA-non-identical BMT group was associated with an age of less than 2 years at the time of transplantation. All the patients with stable long-term engraftment had persistently low CD4 counts after transplantation (105 to 650/microL at last follow up), but no clear susceptibility to opportunistic infections despite persisting MHC class II deficiency on thymic epithelium and other nonhematopoietic cells. We conclude that HLA-identical and -haploidentical BMT can cure MHC class II deficiency, although the success rate of haploidentical BMT is lower than that in other combined immunodeficiency syndromes. HLA-haploidentical BMT should preferably be performed in the first 2 years of life, before the acquisition of chronic virus carriage and sequelae of infections.

Dengue fever virus and Japanese encephalitis virus synthetic peptides, with motifs to fit HLA class I haplotypes prevalent in human populations in endemic regions, can be used for application to skin Langerhans cells to prime antiviral CD8+ cytotoxic T cells (CTLs)--a novel approach to the protection of humans

Flaviviruses were reported to induce CD8+ cytotoxic T cells in infected individuals, indicating that nonapeptides, proteolytic cleavage products of the viral precursor protein, enter the endoplasmic reticulum in infected cells and interact with HLA class I molecules. The assembled HLA class I molecules are transported to the plasma membrane and prime CD8+ T cells. Current knowledge of the interaction of viral peptides with HLA molecules is reviewed. Based on this review, an idea is presented to use synthetic flavivirus peptides with an amino acid motif to fit with the HLA class I peptide binding group of HLA haplotypes prevalent in a given population in an endemic area. These synthetic viral peptides may be introduced into the human skin using a lotion containing the peptides ("Peplotion") together with substances capable of enhancing the penetration of these peptides into the skin to reach Langerhans cells. The peptide-treated Langerhans cells, professional antigen-presenting cells, may bind the synthetic viral peptides by their HLA class I peptide-binding grooves. Antigens carrying Langerhans cells are able to migrate and induce the cellular immune response in the lymph nodes. This approach to the priming of antiviral CD8+ cytotoxic T cells may provide cellular immune protection from flavivirus infection without inducing the humoral immune response, which can lead to the shock syndrome in Dengue fever patients. To be able to develop anti-Dengue virus synthetic peptides for populations with different HLA class I haplotypes, it is necessary to develop computational studies to design HLA class I Dengue virus synthetic peptides with motifs to fit the HLA haplotypes of the population living in an endemic region for Dengue fever. Experiments to study Dengue virus and Japanese encephalitis peptides vaccines and their effectiveness in protection against Dengue fever and Japanese encephalitis are needed. The development of human antiviral vaccines for application of viral peptides in a lotion to human skin ("Peplotion") may be useful and affordable for populations of developing countries.

MHC class II-restricted presentation of endogenously synthesized antigen: Epstein-Barr virus transformed B cell lines can present the viral glycoprotein gp340 by two distinct pathways

Epstein-Barr virus (EBV) transformed B lymphoblastoid cell lines (LCL) efficiently process exogenous antigens for MHC class II-restricted presentation via the chloroquine-sensitive endosomal pathway. Using MHC class II-restricted T cell clones specific for EBV structural proteins, however, we frequently observed significant responses to autologous LCL cells without the addition of exogenous virus. Such responses were reduced by pre-treating the LCL with acyclovir (ACV), a drug blocking productive EBV infection. This suggested T cell recognition of antigen synthesized by LCL cells spontaneously entering virus productive cycle, and led us to question by what route(s) MHC class II-restricted presentation of endogenously synthesized virion proteins was occurring. Cell sorting experiments, using the viral envelope glycoprotein gp340 as a surface marker of productively-infected cells, confirmed that stimulatory activity lay within the gp340-positive fraction. However, closer analysis revealed that most of these cells were not productively-infected but were EBV receptor-positive and had bound released virus. We infer that receptor-mediated delivery of released virus into the endosomal pathway is one route whereby an LCL can present endogenously synthesized EBV proteins on MHC class II molecules. To ask whether another, more direct, route of processing was possible, we used a recombinant vaccinia viral vector to express gp340 de novo in ACV-treated LCLs. Significantly, these cells presented the endogenously synthesized antigen to autologous gp340-specific T cell clones via a chloroquine-resistant pathway. In the same experiments, vaccinia-mediated expression of a signal peptide-deleted form of gp340 did not lead to T cell stimulation, suggesting that this second route of processing required entry of endogenously synthesized antigen into the endoplasmic reticulum.

Conservation of determinants for class II-restricted T cells within site E of influenza virus hemagglutinin and factors influencing their expression

The determinants recognized by helper T cells specific for the site E region of H3 subtype influenza virus hemagglutinin (HA) have been defined by examining the reactivity of T-cell clones with sets of overlapping peptides of various lengths covering the site. Two overlapping sequences, TLIDALLG and LIDALLGDP, were identified as the minimal determinants for four of five representative clones. These sequences are located within a loop of the molecule closed by a disulfide bond and presumably require cleavage of this bond for interaction with the class II major histocompatibility molecule. In contrast, the determinant recognized by the fifth clone was dependent on the presence of an intact disulfide bond for its expression and could not be represented by a synthetic peptide homolog of the linear sequence. Both TLIDALLG and LIDALLGDP are conserved within all field strains of the H3 subtype. Nevertheless, recognition of these sequences by the T-cell clones is affected by the glycosylation pattern of the hemagglutinin and by residues lying outside the minimal determinant. Three distinct clones directed towards the sequence LIDALLGDP were remarkably similar in their pattern of response to a set of synthetic analogs of the determinant, suggesting that residues of the T-cell receptor other than those contacting the minimal determinant may be responsible for the different specificities observed for these clones with different field strains of virus.

[Bronchoalveolar lavage (BAL) in the diagnosis of pulmonary infections in immunocompromised children]

The authors report their personal case records of broncho-alveolar lavage in immuno-compromised children. 22 children were observed from 1991 to 1992 at the E.N.T. Department of the Bambino Gesù Hospital, National Research Institute, in Rome. Flexible bronchoscopy is used under both local and general anesthesia without muscle relaxants. The epithelial lining fluid collection is greater than that obtained when muscle relaxation is used. For each patient 3 specimens are collected: for virological, bacteriological, mycological and immunological analysis. In 90% of the cases a correct etiological diagnosis of the pulmonary disease was possible. In 14 cases the diagnosis was possible even after a week from the beginning of the antibiotic therapy.

Staphylococcal superantigens as inducers of signal transduction in MHC class II-positive cells

Staphylococcal superantigens (SEs and TSST-1) interact with and potentially activate two of the main subsets of the immune system: T lymphocytes and MHC class II-positive cells. Since the interaction of SEs and TSST-1 with MHC class II molecules is the first step in triggering immune cells activation, a detailed understanding of the nature of this interaction is essential for understanding its effect on the immune system and for designing therapeutic strategies for SEs and TSST-1-mediated injury. A series of events is induced in MHC class II-positive cells (B cells, activated T cells, monocytes, and synoviocytes) upon engagement with superantigens. Some of these events require monomeric forms of superantigens, whereas others are critically dependent on cross-linking of toxin-bound MHC class II molecules by a biochemical agent (biotin-avidin) or a natural physiological one such as the TCR. The ability of superantigens to induce polyclonal activation of MHC class II-positive cells may confer to the superantigen its capacity to trigger autoimmune diseases.

Peptide-induced proliferation and lymphokine production in human T cells in the absence of antigen-presenting cells: role of T-cell activation state and costimulatory signals

The role of T-lymphocytes as antigen-presenting cells (APCs) for other T cells was investigated. Activated rabies-virus-specific human T-cell clones were shown to present peptide to class II major histocompatibility complex (MHC)-restricted T cells of a different fine specificity, resulting in lymphokine production and cell proliferation. Furthermore, purified and activated antigen-specific T cells could produce lymphokines and proliferate as a result of the addition of antigenic peptide in the absence of APC. The functional response of T cells to peptide in the absence of APC was amplified by the addition of phorbol ester (PMA) and was inhibited with antibodies specific to class II MHC or to the CD2 molecule. Experiments performed in single-cell suspension cultures using semisolid medium prepared with 1% agar demonstrate that T-cell proliferative and lymphokine responses to peptide both in the presence and absence of APC require the interaction of T-cell antigen receptor (TCR) molecules with class II MHC-peptide complexes on different cell surfaces (cell-cell contact). On the other hand, peptide self-presentation, which occurs by the binding of TCR with class II MHC-peptide complexes on the same cell surface (at the single-cell level), resulted in T-cell activation (i.e., high expression of surface CD2, CD25, and HLA-DR molecules), without proliferation or lymphokine secretion, a pattern observed in the induction of T-cell anergy by antigen. The results are discussed in terms of the role of class II MHC molecules on activated T-lymphocytes, which enable these cells to function as "professional APC" in the development of T-cell regulatory networks.

Preferential expansion of V gamma 9 V delta 2 T cells following stimulation of peripheral blood lymphocytes with extracts of Plasmodium falciparum

A Plasmodium falciparum schizont lysate has been previously described as being a powerful inducer of proliferation for human peripheral T lymphocytes. In this report we study the phenotype of cycling T cells from unexposed donors and examine how the P. falciparum lysate compares with the conventional T cell mitogen phytohemagglutinin (PHA), a known superantigen staphylococcal enterotoxin B (SEB), and a classical antigen pure protein derivative (PPD). We show that for this lymphoproliferative activity interaction with the MHC class II molecule is required and that in the presence of P. falciparum the great majority of the cycling cells at day 6 are gamma delta T cells, all of them bearing V gamma 9 V delta 2. Our results suggest that P. falciparum induces a T cell proliferative response that resembles a response of human peripheral blood gamma delta T cells to superantigen. This observation is in agreement with the elevated level of peripheral gamma delta lymphocytes observed during and after malaria acute infection.

Exacerbation of hypothyroidism following tumor necrosis factor-alpha infusion

A 46-year-old woman with chronic thyroiditis who had been receiving thyroid hormone treatment for 10 yr developed severe hypothyroidism (FT4 0.37 ng/dl, FT3 1.38 pg/ml, TSH 151.00 microU/ml) following tumor necrosis factor-alpha (TNF) infusion for the treatment of a complicated cutaneous T-cell lymphoma. Indirect immunofluorescence staining of thyroid follicular cells showed aberrant expression of HLA class II antigens. The mechanisms underlying the exacerbation of the hypothyroidism may be an augmentation of immunological processes in the thyroid and a direct action of TNF on the synthesis and secretion of thyroid hormone.

Reaction patterns of tumor infiltrating lymphocytes in different renal cell carcinomas and oncocytomas

1. Only clear cell and chromophilic carcinomas of the kidney exhibit a considerable lymphocytic infiltration which is compatible with some immunological responsiveness. Chromophobic carcinomas and benign oncocytomas seem to be immunologically reactive. This reflects the different antigen spectrum and histogenesis of these tumors (Störkel and Jacobi, 1989). Clear cell and chromophilic carcinomas are derived from the proximal tubule and chromophobic carcinomas and oncocytomas from the collecting duct. 2. The tumor periphery seems to be the place of greatest immunological importance, as basic requirements of a sufficient lymphocyte/tumor cell interaction can only be expected there. If these data are taken into account for a therapeutical approach with biological immune modifiers the size of the tumor (tumor burden) and proliferation index must be considered too. This might be a likely explanation for the positive effect of inhaled interleukin-2 on lung metastasis in renal cell cancers. Harvesting of tumor infiltrating lymphocytes for therapeutical purposes should take these findings into account. 3. In spite of dense lymphocytic infiltration only 3% of the tumor infiltrating lymphocytes exhibit the activation marker CD 25. There seems to be a sufficient T cell locomotion in renal cell carcinomas but an insufficient T-cell activation. Whether this fact is induced by lacking cytokine stimulation of involved lymphocytes or by still unknown mediators of the tumor cells is not yet known and needs further investigation. 4. Clear cell carcinomas exhibit most adhesion molecules and the highest amount of infiltrating cytotoxic T-cells and natural killer cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Immune reactivity in aging-autologous mixed lymphocyte responses

The level of activity in the autologous mixed lymphocyte reaction (AMLR) was studied in populations of young and old subjects. AMLR activity was reduced in the older age group. A subpopulation of the older age group who had Alzheimer's disease was shown to have the lowest AMLR values. Within this group, those with a history indicating a more rapid development of CNS-related disability from senescence showed the weakest AMLR responses. The AMLR values correlated neither with sex, nutritional status nor history of infections. This impairment of a central regulating immune reaction may be a significant variable in manifestations of the aging process.

Human peripheral blood gamma delta T cells respond to antigens of Plasmodium falciparum

Peripheral blood lymphocytes from donors previously unexposed to malaria parasites proliferate in vitro when stimulated with whole parasitized red blood cells of several different strains of Plasmodium falciparum. Here we show that both cells enriched for both memory (CD45R0+) and naïve (CD45R0-) phenotype can respond. Cells involved in these responses occur at frequencies similar to those observed for recall antigens such as tetanus toxoid but at lower frequencies than observed for the superantigens staphylococcal enterotoxin B or the mitogenic lectin phytohemagglutinin (PHA). Proliferation is inhibited by antibodies to class II MHC and to CD3 molecules. Stimulation of purified CD45R0- T cells by whole parasitized red blood cells for 6 days results in the generation of a large proportion of gamma delta T cell blasts of V gamma 9V delta 2 TCR phenotype and in the acquisition of the CD45R0 molecule within the blast cell population. The rapid generation of a vigorous primary in vitro gamma delta T cell response by malarial parasites may reflect the situation during primary malarial infection.

Inhibition of T cell activation by blockade of MHC class II molecules

Autoimmune diseases result from the activation of self-reactive T cells induced by autoantigens or by foreign antigens cross-reactive with an autoantigen. A striking characteristic of autoimmune diseases is the increased frequency of certain HLA alleles in affected individuals. Moreover, as demonstrated for example in rheumatoid arthritis and insulin-dependent diabetes mellitus, class II alleles positively associated with autoimmune diseases share amino acid residues in the hypervariable HLA regions involved in peptide binding. Therefore, it is likely that disease-associated HLA class II molecules have the capacity to bind the autoantigen and present it to T cells, thereby inducing and maintaining, under appropriate conditions, the autoimmune disease. The data reviewed here demonstrate MHC-selective inhibition of antigen-induced T cell responses in vivo by parenterally administered soluble, MHC-binding peptide competitors, under conditions in which the competitor is not immunogenic. This suggests the feasibility of a therapeutic approach based on MHC blockade in the treatment of HLA-linked autoimmune diseases.

MHC class-II molecules and autoimmunity

Molecular and genetic studies of HLA class-II genes provide new insights into the basis for MHC associations with autoimmunity. Polymorphisms among class-II genes identify specific haplotypes associated with autoimmune diseases such as type-I diabetes, rheumatoid arthritis, celiac disease, and pemphigus vulgaris. In some cases, single genes within those haplotypes are themselves implicated in disease susceptibility. Interactions, both cis and trans, between candidate susceptibility genes suggest a number of possible mechanisms critical for autoimmune triggering events involving class-II molecules. Amino acid sequence comparisons between products of candidate susceptibility genes and other class-II genes pinpoint a limited number of critical sites within HLA molecules which appear to be responsible for pathogenic events.

Signal transduction in B lymphocytes

We have examined the activity and intracellular compartmentalization of protein kinase C (PKC) following activation of human B lymphocytes by anti-human leukocyte antigen (HLA) class II antibodies. 12-O-Tetradecanoylphorbol 13-acetate (TPA) treatment increased membrane-associated PKC (between five and nine times greater than the control value) and decreased cytosolic PKC (between 70% and 100% of the control value). In contrast, anti-class II antibodies induce an activation of PKC which results either in an increase of cytosolic activity or membrane-bound activity without redistribution of cytosolic PKC. The effect of TPA and HLA class II molecules on total PKC activity was comparable: when TPA induced an increase of total PKC activity so did HLA class II molecules and when TPA did not, HLA class II molecules did not. Measurement on SDS PAGE of histone phosphorylation confirmed the above results of PKC activity. Taken together, our results suggest that PKC might be implicated in HLA class II-induced B lymphocyte activation.

Alloreactive lymphoid infiltrates in human heart transplants. Loss of class II-directed cytotoxicity more than 3 months after transplantation

From 535 endomyocardial biopsies (87 heart transplant recipients) 283 cell cultures could be generated. All cultures tested contained T lymphocytes and in most cases CD4 was the predominant phenotype at any time posttransplant. A significantly higher proportion of CD8-dominated cultures was found among cultures from biopsies without myocytolysis. In the first 3 months post transplant 57% of cultures showed cytotoxicity against both class I and class II mismatched donor major histocompatibility complex (MHC) antigens, changing to an incidence of 33% at greater than 90 days. This proved to be due to a significant decrease in the number of cultures with human leukocyte antigen class II-directed cytotoxicity. This study shows that early after transplantation a heart transplant is infiltrated with activated donor-specific cytotoxic T cells which recognize a broad spectrum of mismatched donor MHC antigens, and that in time this spectrum becomes more restricted.

Recombinant CD4-Pseudomonas exotoxin hybrid protein displays HIV-specific cytotoxicity without affecting MHC class II-dependent functions

The present study describes several in vitro activities of CD4(178)-PE40, a recombinant protein containing a portion of human CD4 linked to active regions of Pseudomonas aeruginosa exotoxin A. Using assays for cell viability, we demonstrate that the hybrid toxin displays highly selective cytotoxicity for HIV-infected T lymphocytes. In a latently infected human T-cell line which is inducible for HIV expression, toxin sensitivity is observed only upon virus induction. At concentrations which readily kill HIV-infected T cells, CD4(178)-PE40 has no observable cytotoxic effects on uninfected human cell lines expressing surface major histocompatibility complex (MHC) Class II molecules, and does not interfere with cellular responses known to be dependent on functional association between CD4 and MHC Class II molecules.

Expression of MHC class II antigens and other T cell activation antigens on T cells and salivary duct epithelial cells in the salivary gland of cases of Sjögren's syndrome

We studied infiltrating T cells and salivary duct epithelial cells in the sublingual glands of 10 patients with primary Sjögren's syndrome (SS) using monoclonal antibodies (MoAb) to T cell subsets (OKT-series), natural killer cells (Leu7) and activation antigens of T cells such as OKT10, OKT9, interleukin 2 receptor (anti-Tac antibody) and major histocompatibility complex (MHC) class II antigens (anti-DR and anti-DQ antigens). DR antigens were identified on salivary duct epithelial cells, suggesting that the cells might function as antigen-presenting cells (APC). Among the salivary duct epithelial cells, OKT8+ cells, which are known to be suppressor/cytotoxic cells, were found in 9 out of 10 patients. Three types of mononuclear cell infiltrations were also evaluated separately: (1) periductal foci, (2) periacinal foci and (3) lymph follicles. We found that the majority of the infiltrating cells in the central portion of the periductal foci were activated T cells (OKT3+, OKT4+, OKIa-1+, DR+ and DQ+), but OKT9, OKT10 and Tac antigens were rarely found in this portion. However, most of the infiltrating cells in the peripheral portion of the periductal foci were OKT10+, and some of them were also positive for OKT9 antigen (transferrin receptor). The results indicated that the T cells in the peripheral portion of the periductal foci are at an early or intermediate phase of activation, whereas the T cells around the salivary ducts are at a later phase. Infiltrating cells in the periacinal foci resembled the cells on the peripheral portion of the periductal foci. Cells within lymph follicles were mainly B cells although scattered OKT4+ or OKT8+ cells were also present.

Structural model for T-cell recognition of HLA class II-associated alloepitopes

In an effort to investigate the structure-function relationship of HLA class II molecules vis-à-vis alloepitope expression, cloned T-cell reagents were used to define polymorphic epitopes associated with DR and DQ molecules. DNA sequences of genes encoding allelic or isotypic DR or DQ molecules that appear to express the same T-cell-defined epitopes were compared in an attempt to identify association of shared sequences with shared epitopes. When sequence sharing is associated with shared epitope expression, we suggest that it is the shared sequence that encodes the epitope in question. Based on the hypothetical three-dimensional structure of the class II molecule, an approximation is made as to which parts of the HLA class II molecule are involved in alloepitope expression. T-cell clones were generated from cells primed against HLA-DR2 haplotypes representing the cellularly defined subgroups Dw2 or Dw21 (previously designated MN2, FJ0, or Tb24). Those clones determined to be DR- or DQ-directed based on monoclonal antibody inhibition assays were tested by panel cell analysis utilizing DR2-positive and DR2-negative target cells. The data support the concept that amino acids 67, 70, 71, and 74 for DR molecules and amino acids 57, 70, and 71 for DQ molecules, which appear to comprise one face of the alpha helix, are of primary importance in T-cell recognition. In other cases, sharing of both the second hypervariable region (amino acids 25-33) and the third hypervariable region (amino acids 67-74) appears necessary to explain epitope sharing for DR molecules. We emphasize that the involvement of these two hypervariable regions may indicate that alloepitope expression involves the complex of class II molecule plus peptide, with the second HVR primarily involved in determining which peptides are bound and the third in T-cell receptor (TcR) recognition and/or peptide binding; we do not rule out that conformational changes of the second HVR can induce conformational changes in the third HVR. Finally, shared alloepitopes detected by some clones could not be explained based on shared primary sequences.

MHC-restricted autoantigen-reactive T cell clones in multiple sclerosis

Multiple sclerosis is a demyelinating disease of the central nervous system with genetic, viral and autoimmune characteristics. Myelin basic protein (MBP) is a suspected target autoantigen since it induces experimental autoimmune encephalomyelitis, an animal model closely resembling multiple sclerosis. The disease is mediated by Class II restricted, MBP-reactive T cells possessing the T helper/inducer phenotype. In the present study, we have isolated MBP-reactive T cell clones from the peripheral blood of a chronic progressive multiple sclerosis patient. The clones displayed blastogenic memory responses when rechallenged with the autoantigen and irradiated autologous lymphocytes. MBP recognition by the autoantigen-reactive T lymphocytes was restricted by major histocompatibility complex Class II antigens. Both CD4+8- and CD4-8+ MBP-reactive T cell clones were obtained.

[Immune response and dentobacterial plaque]

The effects of bacterial plaque on the immunologic response are varied and complex, which is astounding considering the nature of the plaque. The large number of gram-positive and gram-negative bacteria and their products like lipopolysaccharides (LPS), lipoteicoic acids (LTA), dextrans and levanes, permit the activation of most immunologic mechanisms. Both the classical and alternate paths in the complement system are activated, as well as lymphocytes, macrophages, and lymphocyne liberation. Polyclonal mitogens evolving to B lymphocytes may perform an important function in lymphocyte stimulation. An immunogenetic control over the functions of T auxiliary cells has been suggested, with at least one antigen from plaque, and related to the HLA-DR. These reactions may be modulated through potentiating and suppressing effects of some plaque components, thus resulting in a chronic localized inflammatory response.