A relationship between viral infections and the simultaneous or subsequent development of allergic inflammation has often been observed in various clinical situations. Recent studies suggest an intimate relationship between reactivations of herpesviruses including human herpesvirus 6 (HHV-6) and the development of a severe systemic hypersensitivity reaction referred to as drug-induced hypersensitivity syndrome (DIHS).This syndrome has several important clinical features that cannot be solely explained by drug antigen-driven oligoclonal expansion of T cells: they include paradoxical worsening of clinical symptoms after discontinuation of the causative drug. In view of the similarity to GVHD or immune reconstitution syndrome (IRS) in clinical manifestations and emergence of viral infections, the clinical symptoms observed during the course of DIHS and GVHD are likely to be mediated by antiviral T cells that can cross-react with the drug and alloantigens, respectively. In considering common intrinsic properties of the causative drugs to potentially induce immunosuppression, reconstitution of a valid immune response to these viruses, which is typically observed in IRS, may be the most crucial process that takes place after withdrawal of the causative drug in patients with DIHS. Thus, this syndrome should be regarded as a reaction induced by a complex interplay among several herpesviruses (EB virus, HHV-6, HHV-7, and cytomegalovirus), antiviral immune responses, and drug-specific immune responses. This review includes discussion of the pathomechanism, the clinical symptoms, laboratory findings, pathological findings and therapy.

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Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN, Lyell's syndrome) are now considered to be distinct clinical entities within a spectrum of adverse cutaneous drug reactions of increasing severity based on their surface of skin detachment. Within this spectrum, SJS which can be considered as a minor form of TEN is characterized by less than 10% body surface area of skin detachment, and an average reported mortality of 1—5%, whereas TEN is characterized by more than 30% skin detachment, and an average reported mortality 25—35%.
Both SJS and TEN are characterized morphologically by the rapid onset of keratinocyte cell death by apoptosis, a process that results in the separation of the epidermis from the dermis. Recent evidence is supportive of a role for inflammatory cytokines and the death receptor Fas and its ligand FasL in the pathogenesis of keratinocyte apoptosis during TEN. This Fas-mediated keratinocyte apoptosis that is the last step culminating in epidermal detachment in TEN can be inhibited in vitro by antagonistic monoclonal antibodies to Fas, and by intravenous immunoglobulins (IVIG) which have been shown to contain natural anti-Fas antibodies.
Consequently, over the last few years, numerous case reports and 9 non-controlled clinical studies containing 10 or more patients have analyzed the therapeutic effect of IVIG in TEN. Taken together, although each study has its potential biases, 7 of 9 such studies point towards a benefit of IVIG used at doses greater than 2 g/kg on the mortality associated with TEN. These studies should serve as the basis for designing an appropriate prospective trial or for conducting a metaanalysis in the near future, in order to determine the therapeutic efficacy of IVIG in TEN.

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Drug-induced hypersensitivity reactions have been explained by the hapten concept, according to which a small chemical compound is too small to be recognized by the immune system. Only after covalently binding to an endogenous protein the immune system reacts to this so called hapten-carrier complex, as the larger molecule (protein) is modified, and thus immunogenic for B and T cells. Consequently, a B and T cell immune response might develop to the drug with very heterogeneous clinical manifestations.
In recent years, however, evidence has become stronger that not all drugs need to bind covalently to the MHC-peptide complex in order to trigger an immune response. Rather, some drugs may bind directly and reversibly to immune receptors like the major histocompatibility complex (MHC) or the T cell receptor (TCR), thereby stimulating the cells similar to a pharmacological activation of other receptors. This concept has been termed pharmacological interaction with immune receptors the (p-i) concept. While the exact mechanism is still a matter of debate, non-covalent drug presentation clearly leads to the activation of drug-specific T cells as documented for various drugs (lidocaine, sulfamethoxazole (SMX), lamotrigine, carbamazepine, p-phenylendiamine, etc.). In some patients with drug hypersensitivity, such a response may occur within hours even upon the first exposure to the drug. Thus, the reaction to the drug may not be due to a classical, primary response, but rather be mediated by stimulating existing, pre-activated, peptide-specific T cells that are cross specific for the drug. In this way, certain drugs may circumvent the checkpoints for immune activation imposed by the classical antigen processing and presentation mechanisms, which may help to explain the peculiar nature of many drug hypersensitivity reactions.

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Clinicians had suspected for years that drug eruptions were probably mediated by immune mechanisms because their timing suggested sensitization and specific immunologic memory rather than direct toxicity. An immune response to medications was also demonstrated by positive skin tests and by several types of in vitro tests that evidenced immediate or delayed hypersensitivity.
In the last decade several teams of researchers obtained in vitro drug-specific human T-cell clones, in a variety of clinical types of drug eruptions. These clones were produced from blood or skin mononuclear cells of patients with a history of drug reaction by stimulation in vitro with drug. They were either of CD4 or CD8 phenotypes. Drug specific clones were stimulated by the parent drug much more often than by reactive metabolites. That challenged the classical "hapten hypothesis" that the immune response was initiated by reactive metabolites combined to self proteins. The medication usually stimulated specific T-cells after non-covalent binding to major histocompatibility (MHC) molecules on antigen presenting cells. In toxic epidermal necrolysis, T-lymphocytes present at the site of lesions, exhibited a drug specific cytotoxicity against autologous target cells, or allogeneic cells that shared the same HLA than autologous cells. This MHC class I restriction and mediation of death by perforin/granzyme release, is the classical behavior of cytotoxic T lymphocytes, like those operating in the reject of a transplanted organ. MHC restriction could explain the key role of HLA genes as predisposing factors to severe drug reactions. A strong association between HLA and hypersensitivity to abacavir, SJS or TEN to carbamazepine or allopurinol has been recently demonstrated. Resemblance to graft rejection points to the possible therapeution value of immuno suppressive agents.
Most drug eruptions appear to result from T-cell mediated delayed hypersensitivity. The secondary activation of different cascades of cytokines, may contribute to the heterogeneity of clinical presentations.

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Research over the past decade has provided information concerning the onset and treatment of allergic diseases, including bronchial asthma, allergic rhinitis and atopic dermatitis. Recent studies also indicated that allergic inflammation is the basic pathophysiology of allergic diseases and is closely associated with their progression and exacerbation. Our understanding of the mechanism of allergic inflammation with regard to therapeutic agents has improved as a result of immunological and molecular biological studies. While much effort has been paid to developing a new anti-allergic drug, allergic disease has yet to be completely conquered. More extensive research will allow the development of new therapeutics to combat allergic diseases. This article provides an overview of recent advances in the development of anti-allergic drugs.

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Background: We have already reported that antigen-specific IgG1 antibody production in WBB6F1-W/W^v (W/W^v) mice after oral administration of ovalbumin (OVA) was extremely high. Active systemic anaphylaxis (ASA) was induced in these mice after intraperitoneal (i.p.) administration of OVA, and Th2-dominant helper T-cell activation occurred. In this study, we examined the effect of CpG oligodeoxynucleotide (ODN) conjugation of OVA on oral immunization of W/W^v mice.
Methods: W/W^v mice were sensitized by administration of 0.1 mg OVA or CpG ODN-OVA by gavage every day for 4 weeks, and the serum titers of OVA-specific IgG1, IgE, and IgG2a antibody were determined. ASA was induced by i.p. injection of OVA, and the changes in body temperature were monitored. In vitro production of Th1- and Th2- type cytokines by splenocytes re-stimulated with antigen was also measured.
Results: The antigen-specific IgG1 antibody titer in the CpG ODN-OVA-sensitized W/W^v mice was lower than in the OVA-sensitized group, but the IgG2a titer was higher. ASA was not induced by i.p. OVA challenge. There were significant increases in the production of Th1-type cytokine (IFN-γ) by splenocytes in the CpG ODN-OVA-sensitized mice, but the Th2-type cytokine (IL-4) level in the splenocyte culture medium was lower.
Conclusions: These results indicated that oral administration of CpG ODN-OVA conjugate significantly induced antigen-specific Th1 responses and reduced Th2 responses (allergic reactions) on re-stimulation. These findings suggest that CpG ODN-antigen conjugate may be useful as an oral vaccine.

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Background: Human interferon-gamma (hIFN-γ) is produced by lymphocytes and has a variety of biological properties. Measurement of hIFN-γ is widely used for various immunological responses for allergic or autoimmune diseases. Enzyme-linked immunosorbent assay (ELISA) is an established immunoassay used to quantify cellular metabolites or cytokines. ELISA requires many incubation and wash steps and is not practically suitable for screening large numbers of samples.
Methods: We have developed a fluorescence-linked immunosorbent assay (FLISA) method for the detection of hIFN-γ. We measured the 50% inhibitory concentration (IC₅₀) value of the hIFN-γ production by interleukin (IL)-18 binding protein and anti-IL-18 monoclonal antibody. The IC₅₀ described by FLISA was compared with that by ELISA.
Results: We developed a new system for measuring hIFN-γ using Allophycocyanine (APC) fluorescent protein and compared it with the previous method using Cy5.5. The proposed FLISA had a smaller coefficient of variation than ELISA, and the means of coefficient of variation using the same samples measured by ELISA and FLISA were, respectively, 11.1% and 3.8%, suggesting that the edge effect often giving non-specific results may be smaller in FLISA than in ELISA.
Conclusions: The improved FLISA system proposed is ideally suited for efficient measurements of hIFN-γ. This homogeneous and multiplex method will be a powerful tool for high throughput screening for drug discovery research.

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Background: CD14 is an essential component of the receptor for lipopolysaccharide (LPS) . LPS stimulates T-helper type 1 (Th1) cytokine expression, potentially suppressing Th2 immune responses involved in IgE-mediated allergic diseases. Previous studies have reported that -159C/T, a promoter polymorphism of CD14, is associated with total serum IgE levels and atopy, but other studies have shown conflicting results.
Methods: To examine possible associations of CD14 polymorphisms with asthma susceptibility, we performed transmission disequilibrium tests (TDTs) of 137 Japanese families identified through children with atopic asthma.
Results: We found no association between -159C/T polymorphism and asthma (p= 0.37). Quantitative TDT and ANOVA showed no association between the -159C/T genotype and total serum IgE levels. We also performed a meta-analysis of data from all available studies. Neither a fixed-effects model nor a random-effect model showed a significant odds ratio for the -159C/T polymorphism (p > 0.1).
Conclusions: Our data indicate that CD14 does not contribute substantially to susceptibility to asthma. Further studies examining both genotypes and environmental factors will be necessary to elucidate the role of CD14 in the development of allergic diseases.

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Background: Asthma is a chronic disease prevalent in children which threatens their quality of life (QOL) through unexpected asthma attacks and/or the burden of daily self-management. As some conditions of chronic illness make it difficult for a child to accomplish normal developmental tasks, there may be fewer opportunities for the child to obtain a sense of achievement. This study investigated the reliability and validity of the Quality of Life Questionnaire for Japanese School-aged Children with Asthma Version 3 (JSCA-QOL v.3). This questionnaire includes 25 items with a 5-point Likert Scale format over five domains:"asthma attack triggers", "change in daily life", "family support", "satisfaction with daily life" and "restriction in participating in daily activities", and one summary scale.
Methods: In the present study, 2,425 children with asthma aged from 10 to 18 years were investigated in Japan. The internal consistency reliability of each domain was investigated with Cronbach's α reliability coefficient, and test-retest reliability with Spearman's correlations coefficient. Factorial validity by factor analysis using maximum-likelihood extraction with promax rotation was performed. Data analysis was performed using SPSS 12.0J.
Results: The final number of effective replies was 2,097 (the rate of effective data was 86.5%). "Asthma attack triggers", "change in daily life", "family support", "satisfaction with daily life" and "restriction in participating in daily activities" showed a high internal consistency (Cronbach's α = 0.66—0.86) as well as good test-retest reliability (Spearman's rho = 0.60, p < 0.01).
The factorial validity was appropriate (KMO value = 0.90), because it was conceivable that the five factors extracted from factor analysis would be the same as in our hypothesis and support constructive validity. In addition, there was good correlation between the summary scale and the total QOL score (Spearman's rho = 0.58, p < 0.01).
Conclusions: The present study showed that the JSCA-QOL v.3 is a reliable and valid measurement tool that can be used to appropriately assess QOL in school-aged children with asthma. As the JSCA-QOL v.3 can be easily completed in about 10 minutes, it can contribute as an efficient evaluation tool of the outcome of medical treatment through continual utilization in the outpatient clinic. The JSCA-QOL v.3 allows a health provider to help school-aged children with asthma to achieve their developmental tasks.

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Background: Matrix metalloproteinases (MMPs) have been reported to play crucial roles in the migration of inflammatory cells through basement membrane components. To confirm the role of mast cells as a source of MMPs, we investigated the production of MMP and its pathway in human cultured mast cells (HCMC). We also investigated the production of tissue inhibitors of metalloproteinase (TIMPs).
Methods: HCMC was stimulated with phorbor 12-miristate 13-acetate (PMA) and/or calcium ionophore A23187 (A23187), and the resulting MMP production was evaluated by gelatin zymography and western blotting. Expression of MMP and TIMP mRNA was also examined. Granulocyte macrophage-colony stimulating factor (GM-CSF) was measured by ELISA and activation of extracellular signal-regulated kinase (ERK) was evaluated by western blotting.
Results: We detected the de novo synthesis of MMP-9 in HCMC after stimulation with PMA and found that the synthesis was mediated through protein kinase C—mitogen activated protein kinase kinase (MEK)—ERK pathway. The MMP-9 production induced by PMA was suppressed by simultaneous treatment with A23187, whereas GM-CSF production was potentiated. We also detected the expression of mRNA for membrane-type 1 (MT1)-MMP, TIMP-1 and TIMP-2 after stimulation with PMA. Glucocorticoids and flavonoids inhibited MMP-9 production, and TIMPs and MMP inhibitors inhibited the gelatinolytic activity of mast cell-derived MMP-9. Furthermore, phenylmethylsulfonyl fluoride, a protease inhibitor, inhibited the conversion from proMMP-9 to active MMP-9.
Conclusions: These results suggest that the human mast cell is a leading member of MMP production, and the production, activation and activity are controllable by pharmacological agents.

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Background: Receptor-interacting protein (RIP)-2 is a serine/threonine kinase containing a caspase recruitment domain (CARD) that is involved in the Toll-like receptor-signaling pathway. Although associations between endotoxin exposure or respiratory infection and asthma have been recognized, the genetic influences in these conditions are unclear. The aim of our study was to examine whether polymorphisms or haplotypes in RIP2 were associated with childhood atopic asthma in a Japanese population.
Methods: We screened the RIP2 gene for polymorphisms by direct sequencing and characterized the linkage disequilibrium (LD) mapping of the gene. Seven variants were genotyped in childhood atopic asthma (n = 300) and normal controls (n = 637) . We conducted case-control and case-only association studies between the variants and asthma-related phenotypes. Haplotype association analyses were also performed.
Results: A total of 31 variants were identified and none of the alleles or haplotypes of RIP2 were associated with asthma susceptibility. In the case-only study, an association between an RIP2 promoter polymorphism and childhood severe asthma (P=0.0032; odds ratio (OR) 3.37, 95% confidence interval (CI) 1.45—7.87) was observed.
Conclusions: Although polymorphisms in RIP2 are not likely to be associated with the development of asthma, the genetic variants might contribute to asthma severity in the Japanese population.

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Background: Anaphylaxis is one of the severest forms of allergic diseases. Some kinds of mushroom are known as causative allergens in food anaphylaxis. Matsutake mushroom (Tricholoma matsutake) is a typical edible mushroom available in autumn in Japan. We encountered an 8-year-old Japanese girl who developed anaphylaxis after ingesting matsutake mushrooms.
Methods: We studied the case in detail, by measuring specific IgE antibodies and conducting skin tests, to confirm the diagnosis. We also detected seven cytokines and chemical mediators in the blood in order to study the pathophysiology of the anaphylaxis.
Results: We diagnosed anaphylaxis caused by ingestion of matsutake mushrooms based on the following. A skin prick test showed a positive reaction to matsutake mushroom, and specific IgE antibody for matsutake mushroom extract was detected in the patient's serum by fluorometric ELISA. Blood levels of chemical mediators including histamine, ECP, tryptase and cytokines such as IL-6, IL-5 and IL-10 but not IFN-γ also increased significantly during the allergic episode.
Conclusions: We demonstrated that chemical mediators including histamine, tryptase and ECP as well as several cytokines were involved significantly during the episode of anaphylaxis. In addition, eosinophils as well as mast cells played significant roles in the anaphylaxis. Furthermore, CD4⁺CD25⁺ T regulatory cells that released IL-10 were likely activated during the anaphylaxis. Matsutake mushroom should be considered as a causative allergen in food anaphylaxis.

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