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Nickel (Ni) in ambient air may vary regionally with contributions from both natural processes and anthropogenic activities. Exposure to Ni compounds in ambient air above a certain level is associated with acute adverse effects, such as upper respiratory tract irritation, pneumonitis, and chronic adverse effects, such as respiratory cancer. Inhalation reference exposure standards are enacted in different jurisdictions to minimize exposures to ambient Ni above levels that can elicit adverse effects. This paper reports a guideline-/GLP-compliant study designed for setting inhalation exposure standards to protect from immunological effects associated with acute exposure to Ni. Female CD-1 mice were exposed via whole-body inhalation to aerosolized nickel chloride hexahydrate for 24-hr at nominal (vs. mean analyzed) concentrations of 20 (16), 50 (44) and 100 (81) µg Ni/m3. Host T-cell antibody immunological responses to intravenously-injected sheep red blood cells were then measured ex vivo in an Antibody-Forming Cell (AFC) assay. Exposure to the Ni substance significantly decreased spleen cell levels by 33%, but this was within biological variability for outbred mice. No concurrent decreases in spleen, thymus, or body weights were noted. No immunosuppression was observed with the Ni substance in the context of Total Spleen Activity [IgM AFC/spleen (× 103)] and Specific Activity [IgM AFC/spleen cells (× 106)]. Significant concentration-independent increases in Total Spleen Activity and Specific Activity seen with the nickel chloride hexahydrate were normal and within biological variability for outbred mice. In contrast, cyclophosphamide (positive control) significantly decreased spleen cell numbers, spleen and thymus weights, and abolished Specific Activity and Total Spleen Activity. Based on results here, an NOAEC of 81 µg Ni/m3 for immunosuppressive effects from inhaled nickel chloride hexahydrate was identified. It is hoped this value can be used to derive a reference standard for human exposure to ambient Ni. [ABSTRACT FROM AUTHOR]

Increased expectations from a number of regulatory agencies, e.g., Environmental Protection Agency (EPA), Food and Drug Administration (FDA), European Medicines Agency (EMEA), and the Ministry of Health, Labour and Welfare (MHLW) of Japan, call for the evaluation of potential adverse effects on the immune system. As recently summarized in the ICH S8 guideline, the T-cell-dependent antibody response (TDAR) has been identified in a regulatory context as a main functional test of immunotoxicity. While the characterization of immunotoxic potential is pertinent to both the chemical and pharmaceutical industries, the use of immunotoxicology data for hazard identification and/or risk assessment in each case is different. Therefore, multiple approaches to immunotoxicity testing have evolved. The assays that evaluate TDAR function include both well-established tests, e.g., anti-sheep red blood cell plaque-forming cell (PFC) assay, and newer models, e.g., anti-keyhole limpet hemocyanin (KLH) antibody ELISA. These tests vary in the study design, antigen application and analytical methods. However, they all evaluate the same endpoint - a competent immune (e.g., antibody) response to an antigen. Numerous issues have been identified in the application of TDAR tests, including high animal to animal variability; differences in antigen source and potency; a lack of established "normal range" of the immune response and uncertainty about the degree of inhibition of the TDAR to be considered toxicologically important. As such, the need for a forum to discuss these issues was recognized by the immunotoxicology community, and was addressed at the 2006 Society of Toxicology (SOT) Workshop. A series of papers will summarize that forum with the ultimate objectives being to build a consensus among immunotoxicologists on the implications of these factors on using TDAR results in hazard identification and/or risk assessment, and to establish a criteria to classify compounds as immunotoxicants. [ABSTRACT FROM AUTHOR]

The number of anti-inflammatory and immunomodulatory drugs being developed in the pharmaceutical industry has increased considerably in the past decade. This increase in research and development has been paralleled by questions from both regulatory agencies and industry on how best to assess decreased host resistance to infections or adverse immunostimulation caused by immunomodulatory agents such as anti-cytokine antibodies (e.g., the tumor necrosis factor-α inhibitors), anti-adhesion molecule antibodies (e.g., anti-α-4 integrin inhibitors) and immunostimulatory molecules (e.g., anti-CD28 antibodies). Although several methods have been developed for nonclinical assessment of immunotoxicity, highly publicized adverse events have brought to light significant gaps in the application of nonclinical immunotoxicity testing in assessing potential risk in humans. Confounding this problem is inconsistent application of immunotoxicology methods for risk assessment within the scientific community, limited understanding of appropriate immunotoxicity testing strategy for immunomodulators and inconsistent testing requests by regulatory agencies. To address these concerns, The Immunotoxicology Technical Committee (ITC) of the International Life Science Institute (ILSI) Health and Environmental Sciences Institute (HESI) organized a workshop on Immunomodulators and Clinical Immunotoxicology in May 2007. The Workshop was convened to identify key gaps in nonclinical and clinical immunotoxicity testing of anti-inflammatory and immunomodulatory agents and to begin to develop consistent approaches for immunotoxicity testing and risk assessment. This paper summarizes the outcome of the HESI ITC Immunomodulators and Clinical Immunotoxicology Workshop. Topics not discussed at the Workshop were outside the scope of this report. Although more work is needed to develop consistent approaches for immunotoxicity assessment of immunomodulators, this Workshop provided the foundation for future discussion. [ABSTRACT FROM AUTHOR]

Immunogenicity is an important factor that manufacturers must consider as they develop new protein therapeutics. It is important to understand the immunogenicity of new proteins both at the preclinical phase and in the clinical phase of development. This paper provides an overview of the issues that manufacturers should consider including some of the potential reasons that some proteins induce an immune response, a discussion regarding current methodology used to understand immunogenicity, and some examples of marketed protein therapeutics with immunogenicity issues. Given the increasing scrutiny from regulatory agencies around the way immunogenicity is assessed by manufacturers, the strategy of detecting and characterizing antibodies that are formed against protein therapeutics is becoming an important topic. Screening assays are typically performed first on all serum samples collected in the course of a trial to detect the presence of antibodies that can bind to the protein therapeutic. There are several platforms in use: radioimmune precipitation assays (RIP), enzyme linked immunosorbent assays (ELISA), electrochemiluminescent assays (ECL), and biosensor-based assays. Each has its advantages and disadvantages, and needs to be evaluated to identify the optimal platform for a specific therapeutic protein. Once antibodies are identified, a confirmatory assay is performed to verify and characterize the antibodies. A biological assay should be used next to test if these antibodies are capable of neutralizing the biological effect of the drug. Any sample that is positive for neutralizing antibodies, indicates that the antibody is probably having an impact on the patient's ability to derive full benefit from the therapeutic protein, and may be critical for patient safety. [ABSTRACT FROM AUTHOR]

Recent studies suggest that exposure to perfluorinated alkylate substances (PFASs) may induce immunosuppression in humans and animal models. In this exploratory study, 12 healthy adult volunteers were recruited. With each subject, serum-PFAS concentrations were measured and their antibody responses prospectively followed for 30 days after a booster vaccination with diphtheria and tetanus. The results indicated that serum-PFAS concentrations were positively correlated and positively associated with age and male sex. The specific antibody concentrations in serum were increased from Day 4 to Day 10 post-booster, after which a constant concentration was reached. Serum PFAS concentrations showed significant negative associations with the rate of increase in the antibody responses. Interestingly, this effect was particularly strong for the longer-chain PFASs. All significant associations remained significant after adjustment for sex and age. Although the study involved a small number of subjects, these findings of a PFAS-associated reduction of the early humoral immune response to booster vaccination in healthy adults supported previous findings of PFAS immunosuppression in larger cohorts. Furthermore, the results suggested that cellular mechanisms right after antigen exposure should be investigated more closely to identify possible mechanisms of immunosuppression from PFAS. [ABSTRACT FROM AUTHOR]

Tetanus is a highly fatal disease caused by tetanus neurotoxin (TeNT) and remains a major threat to human and animal health, despite preventive strategies. TeNT is composed of heavy and light chain linked by a disulfide bond. The antibody response to TeNT is polyclonal and directed to multiple epitopes within both the light and heavy chains, leading to toxin neutralization. This study was undertaken to localize and compare neutralizing epitopes recognized by human and mouse TeNT-specific antibodies at a clonal level. In the present study, 22 murine hybridoma clones and 50 human lymphoblastoid cell lines secreting monoclonal antibodies (mAb) were generated against TeNT. The specificity of these mAb was determined using different recombinant fragments of tetanus toxin. Moreover, this study investigated thein vitrotoxin neutralizing activity of these mAb by a ganglioside GT1b assay. The results showed that tetanus toxoid immunization in humans and BALB/c mice induced a vigorous humoral immune response against different fragments of TeNT, particularly the carboxyl-terminal fragment of the heavy chain (known as fragment C). The fragment C-specific human and mouse mAb could largely neutralize TeNT. However, while all fragment C-specific human mAb reacted with the carboxyl-terminal part of this fragment (HCC), the majority of the mouse mAb failed to recognize this region. These results suggested that fragment C is the major target for the TeNT neutralizing antibodies, although different epitopes seem to be targeted by human and mouse antibodies. [ABSTRACT FROM AUTHOR]

T-cell-dependent antibody responses (TDAR) are suppressed in female C57BL/6N mice exposed to ≥3.75 mg/kg of perfluorooctanoic acid (PFOA) for 15 days. To determine if suppression of humoral immunity by PFOA is peroxisome proliferator activated receptor alpha (PPARα)-dependent and if suppression is associated with specific targeting of T- or B-cells, three separate experiments were conducted: (1) female PPARαconstitutive knockout (PPARαKO; B6.129S4-Ppartm1GonzN12) and wild-type controls (WT; C57BL/6-Tac) exposed to 0, 7.5, or 30 mg PFOA/kg for 15 days were immunized on Day 11 with a T-cell-dependent antigen and sera then collected for measures of antigen-specific IgM titers (TDAR) 5 days later; (2) female C57BL/6N WT mice exposed to 0, 0.94, 1.88, 3.75, or 7.5 mg PFOA/kg for 15 days were immunized with a T-cell-independent antigen on Day 11 and sera were then collected for analyses of antigen-specific IgM titers (TIAR) 7 days later; and (3) splenic lymphocyte phenotypes were assessed in unimmunized female C57BL/6N WT mice exposed to 0, 3.75, or 7.5 mg PFOA/kg for 10 days to investigate effects of PFOA in the absence of specific immunization. Separate groups of mice were immunized with a T-cell-dependent antigen after 11 days of exposure and splenic lymphocyte sub-populations were assessed after 13 or 15 days of exposure to assess numbers of stimulated cells. The results indicated that exposure to ≥1.88 mg PFOA/kg suppressed the TIAR; exposure to 30 mg PFOA/kg suppressed the TDAR in both PPARαKO and WT mice. The percentage of splenic B-cells was unchanged. Results obtained in the PPARαKO mice indicated that PPARαsuppression of TDAR was independent of PPARαinvolvement. Suppression of the TIAR and the TDAR with minimal lymphocyte sub-population effects suggested that effects on humoral immunity are likely mediated by disruption of B-cell/plasma cell function. [ABSTRACT FROM PUBLISHER]

The elicitation of anti-drug antibodies (ADA) against biotherapeutics can have detrimental effects on drug safety, efficacy, and pharmacokinetics. The immunogenicity of biotherapeutics is, therefore, an important issue. There is evidence that protein aggregation can result in enhanced immunogenicity; however, the precise immunological and biochemical mechanisms responsible are poorly defined. In the context of biotherapeutic drug development and safety assessment, understanding the mechanisms underlying aggregate immunogenicity is of considerable interest. This review provides an overview of the phenomenon of protein aggregation, the production of unwanted aggregates during bioprocessing, and how the immune response to aggregated protein differs from that provoked by non-aggregated protein. Of particular interest is the nature of the interaction of aggregates with the immune system and how subsequent ADA responses are induced. Pathways considered here include 'classical' activation of the immune system involving antigen presenting cells and, alternatively, the breakdown of B-cell tolerance. Additionally, methods available to screen for aggregation and immunogenicity will be described. With an increased understanding of aggregation-enhanced immune responses, it may be possible to develop improved manufacturing and screening processes to avoid, or at least reduce, the problems associated with ADA. [ABSTRACT FROM AUTHOR]

In Brazil, scorpion envenomation is an important public health problem. The yellow scorpion, Tityus serrulatus (Ts), is considered the most dangerous species in the country, being responsible for the most severe clinical cases of envenomation. Currently, the administration of serum produced in horses is recognized and used as a treatment for accidents with scorpions. However, horse herds' maintenance is costly and the antibodies are heterologous, which can cause anaphylaxis and Serum Sickness. In the present work, a human monoclonal fragment antibody, Serrumab, has been analysed. Toxin neutralizing effects of Serrumab were evaluated using a two-electrode voltage-clamp technique. The results show that Serrumab presented a high neutralizing effect against Ts β-toxins (Ts1, 43.2% and Ts2, 68.8%) and none or low neutralizing effect against α-toxins (Ts3, 0% and Ts5, 10%). Additional experiments demonstrated that Serrumab was also able to neutralize the action of toxins from other scorpion genus (Css II, 45.96% and Lqh III, 100%/β- and α-toxins, respectively). This work indicated that Serrumab is able to neutralize many toxins in Ts venom, and could being considered as a neutralizing antibody for formulating a human anti-scorpion serum in Brazil. Additionally, this work demonstrated that Serrumab could neutralize different toxins from distinct scorpion genus. All these results reinforce the idea that Serrumab is a scFv antibody with multiple neutralizing capacities and a promising candidate for inclusion in scorpion anti-venoms against different genera. [ABSTRACT FROM AUTHOR]

The adjuvanticity of aluminum hydroxide and calcium phosphate on the antibody response in mice towards the venom of the snake Bothrops asper was studied. It was found that, in vitro, most of the venom proteins are similarly adsorbed by both mineral salts, with the exception of some basic phospholipases A2, which are better adsorbed by calcium phosphate. After injection, the adjuvants promoted a slow release of the venom, as judged by the lack of acute toxicity when lethal doses of venom were administered to mice. Leukocyte recruitment induced by the venom was enhanced when it was adsorbed on both mineral salts; however, venom adsorbed on calcium phosphate induced a higher antibody response towards all tested HPLC fractions of the venom. On the other hand, co-precipitation of venom with calcium phosphate was the best strategy for increasing: (1) the capacity of the salt to couple venom proteins in vitro; (2) the venom ability to induce leukocyte recruitment; (3) phagocytosis by macrophages; and (4) a host antibody response. These findings suggest that the chemical nature is not the only one determining factor of the adjuvant activity of mineral salts. [ABSTRACT FROM AUTHOR]

Approximately 20,000 snakebites are registered each year in Brazil. The classical treatment for venomous snakebite involves the administration of sera obtained from immunized horses. Moreover, the production and care of horses is costly, and the use of heterologous sera can cause hypersensitivity reactions. The production of human antibody fragments by phage display technology is seen as a means of overcoming some of these disadvantages. The studies here attempted to test human monoclonal antibodies specific to Bothrops jararacussu against other Bothrops sp. venoms, using the Griffin.1 library of human single-chain fragment-variable (scFv) phage antibodies. Using the Griffin.1 phage antibody library, this laboratory previously produced scFvs capable of inhibiting the phospholipase and myotoxic activities of Bothrops jararacussu venom. The structural and functional similarities of the various forms of phospholipase A2 (PLA2) in Bothrops venom served as the basis for the present study wherein the effectiveness of those same scFvs were evaluated against B. jararaca, B. neuwiedi, and B. moojeni venoms. Each clone was found to recognize all three Bothrops venoms, and purified scFvs partially inhibited their in vitro phospholipase activity. In vivo assays demonstrated that the scFv clone P2B7 reduced myotoxicity and increased the survival of animals that received the test venoms. The results here indicate that the scFv P2B7 is a candidate for inclusion in a mixture of specific antibodies to produce a human anti-bothropic sera. This data demonstrates that the human scFv P2B7 represents an alternative therapeutic approach to heterologous anti-bothropic sera available today. [ABSTRACT FROM AUTHOR]

Previous studies indicate that exposure to perfluorooctanesulfonate (PFOS), a ubiquitous and highly persistent environmental contaminant induces immunotoxicity in mice. However, clear mechanisms to explain any PFOS-induced immunotoxicity are still unknown. The study here sought to examine the ability of PFOS to potentially perturb T-helper (TH)-1 and -2 cell cytokine secreting activities, as well as to cause shifts in antibody isotype levels, as possible mechanisms involved in PFOS-induced immunotoxicity. Adult male C57BL/6 mice were given by gavage 0, 5, or 20 mg PFOS/kg/d for 7 days. One day after the final exposure, spleens from these hosts were isolated and used for analyses of the ex vivo production of TH1-type (interleukin-2 (IL-2), interferon-γγ (IFNγγ)), TH2-type (IL-4), and IL-10 cytokines by isolated splenocytes. In addition, serum was isolated from these mice in order to assess their levels of immunoglobulin M (IgM) and IgG antibodies. In all studies, levels of the cytokines of the antibodies were quantified via enzyme-linked immunosorbent assay or enzyme-linked immunosorbent spot. The results here showed that IL-2 and IFNγγ formation was reduced, but that IL-4 production increased by the 5 and 20 mg PFOS/kg/d treatments. Serum IgM levels decreased significantly (in dose-related manner) as a result of the PFOS exposures; serum IgG levels increased markedly with 5 mg PFOS/kg/d, but decreased slightly with the 20 mg PFOS/kg/d regimens PFOS exposure increased serum corticosterone levels in a dose-dependent manner. These results indicated that, after a high-dose short-term exposure to PFOS, a host''s immune state is likely to be characterized by a shift toward a more TH2-like state that, in turn, may lead to suppression of their cellular response and enhancement of their humoral response. [ABSTRACT FROM AUTHOR]

The toxic effect of paraquat (PQ), an herbicide that has been used widely in agriculture, on some parameters of the immune system was investigated. PQ was administered to Balb/c mice as intraperitoneal doses of 0.01, 0.1, or 1.0 mg PQ/kg body weight (BW) for a total of 28 days. Besides the histopathological examination of each host''s vital organs, measures of their splenic and bone marrow cellularity, blood macrophage/granulocyte phagocytic activity, total serum immunoglobulin M (IgM) and IgG, complement C3, and splenic CD49b (natural killer) cell levels, as well as of serum aspartate aminotransferase, alanine aminotransferase, and lactate dehydrogenase and complement-mediated lytic activity (CH50), activities, were then performed following the respective final treatments. The results indicate that high and medium doses of PQ (i.e., 1 and 0.1 mg/kg) could lead to suppressed phagocytic activity by circulating macrophages/granulocytes. The data also revealed that the high PQ dose induced a significant decrease ( p < 0.05) in spleen cellularity and splenic CD49b cell levels, along with numerous histopathological changes in the spleen. However, at none of the doses tested did PQ produce changes in serum levels of C3, total IgG or IgM, or in the CH50. At 0.01 mg PQ/kg/day, no histopathological or functional disturbances were detected. These results indicate that PQ at doses more than 0.1 mg/kg has toxic effects on the cellular components of the innate immune system of Balb/c mice. The present results, however, indicate that at an exposure level below the recommended acceptable daily intake limit of 0.005 mg/kg, no observable immunotoxicity effect might be expected. [ABSTRACT FROM AUTHOR]

Vigna mungo L. ( Fabaceae) is a popular food legume used in the traditional Indian system of medicine for the treatment of a variety of disease conditions. The objective of the study was to evaluate any immunostimulatory activities of the extract of V. mungo seeds in an animal model. The induction of any immunostimulatory effects were evaluated using measures of sheep red blood cells (SRBC)-induced humoral antibody titer, SRBC-induced delayed-type hypersensitivity (DTH), neutrophil adhesion, and in vivo phagocytosis (via the carbon clearance method) after host treatment with the extract. The results here indicated that primary and secondary antibody titers in the rats were significantly increased by treatment with the V. mungo extract as compared with those noted among rats in a control group. Increases in response, the percentage (%) neutrophil adhesion, and in situ phagocytosis were also observed after treatment with the extract. We summarize that the apparent immunostimulatory effect of the V. mungo seed extract might be attributed to an augmentation of humoral and cell-mediated responses, phagocytosis, and hematopoiesis in the treated rats. The findings in this study suggest that V. mungo seed extract possesses profound immunostimulatory activities. Whether such outcomes are also evidenced by consumption of the intact seeds themselves, as is most likely to be the case with humans, remains to be determined. Nonetheless, the present study provides evidence that could help explain how the traditional use of V. mungo has been successful in the treatment of various disorders in humans. [ABSTRACT FROM AUTHOR]

Measurements of antibodies in bodily fluids (e.g., by ELISA) have provided robust and reproducible results for decades and such assays have been validated for monitoring of B-cell immunity. In contrast, measuring T-cell immunity has proven to be a challenge due to the need to test live cells in functional assays ex vivo. Several previous efforts looking into the reproducibility of ex vivo T-cell assays between different laboratories, or even within the same laboratory, have provided rather discouraging results. The hypothesis we tested in this study is that those poor results are due to the lack of assay and data analysis standardization, rather than the inherent complexity of T-cell assays. In this study, 11 laboratories across Europe and the United States were provided identical reagents and were asked to follow the same protocol while testing aliquots of the same three cryopreserved peripheral blood mononuclear cells (PBMC) in an interferon-γ (IFNγ) ELISPOT assay measuring the antigen-specific T-cell response to a CMV peptide. All individuals performing the assays were ELISPOT novices. At their first attempt, while three of these individuals failed with the basic logistics of the trial, eight detected the peptide-specific CD8+ T-cells in frequencies approximating the values established by the Reference Laboratory. The data show that ELISPOT assays provide reproducible results among different laboratories when the assay procedure and data analysis is standardized. Since ELISPOT assays have been qualified and validated for regulated studies, they are ideal candidates for robust and reproducible monitoring of T-cell activity in vivo. [ABSTRACT FROM AUTHOR]

Natalizumab is a monoclonal antibody to human α4 integrin indicated for treatment of multiple sclerosis and Crohn’s disease that prevents extravasation of leukocytes into surrounding tissues and their involvement in inflammation. Because α4 integrins and their receptors are involved in hematopoiesis and immune cell trafficking, natalizumab may interfere with these processes. We evaluated the effects of natalizumab on immune function in monkeys using in vitro and in vivo studies. Consistent with the pharmacologic effects of natalizumab, dose-related increases in white blood cell counts and spleen weights were observed. Administration to monkeys did not result in statistically significant alterations in the percentages of circulating B-cells, T-cells, T-cell subsets (CD4, CD8), or stem cells (CD34). A modest and highly variable delay in the primary humoral response to T-cell-dependent antigens was observed. Ex vivo studies using cells from natalizumab-treated monkeys demonstrated that treatment did not alter immune regulatory or effector cell functions in blood lymphocytes or spleen cells. A similar lack of effect on these functions was observed in vitro following treatment of PBMC and monocytes from human donors. Overall, natalizumab was well tolerated in monkeys, demonstrated the expected pharmacologic effect on cell trafficking, and showed no adverse effect on immune cell function. [ABSTRACT FROM AUTHOR]

Biologic pharmaceuticals include a variety of products, such as monoclonal antibodies, fusion proteins and cytokines. Products in those classes include immunomodulatory biologics, which are intended to enhance or diminish the activity of the immune system. Immunomodulatory biologics have been approved by the U.S. FDA for a variety of indications, including cancer and inflammatory conditions. Prior to gaining approval for marketing, sponsoring companies for all types of products must demonstrate a product's safety in toxicology studies conducted in animals and show safety and efficacy in clinical trials conducted in patients. The overall goal of toxicology studies, which applies to immunomodulatory and other product types, is to identify the hazards that products pose to humans. Because biologics are generally highly selective for specific targets (receptors/epitopes), conducting toxicology studies in animal models with the target is essential. Such animals are referred to as pharmacologically relevant. Endpoints routinely included in toxicology studies, such as hematology, organ weight and histopathology, can be used to assess the effect of a product on the structure of the immune system. Additionally, specialized endpoints, such as immunophenotyping and immune function tests, can be used to define effects of immunomodulatory products on the immune system. Following hazard identification, risks posed to patients are assessed and managed. Risks can be managed through clinical trial design and risk communication, a practice that applies to immunomodulatory and other product types. Examples of risk management in clinical trial design include establishing a safe starting dose, defining the appropriate patient population and establishing appropriate patient monitoring. Risk communication starts during clinical trials and continues after product approval. A combination of hazard identification, risk assessment and risk management allows for drug development to proceed with minimum risks to patients. [ABSTRACT FROM AUTHOR]

The primary T-cell-dependent antibody response (TDAR) to antigens is widely used as a functional test in immunotoxicology. TDAR assays can be performed using different antigens, e.g., sheep red blood cells (SRBC) and keyhole limpet hemocyanin (KLH) are presently utilized by different laboratories. The purpose of this study was to apply meta-analysis to compare data from several laboratories using these antigens, in two strains of rats, by multiple routes of immunization and with different primary TDAR assay formats. Although limitations imposed by the scale of the data set and the need to convert some data to an ordinal scale to allow comparisons restrict the scope and strength of the conclusions that can be drawn, the results of this study have shown that the two antigens in different assay formats give comparable results. Similarly, both antigens and assays formats showed the same pattern of response to strong immunotoxicants. These results indicate that standardizing the choice of antigen in TDAR assays may not be critical in the evaluation of potential immunotoxicity. [ABSTRACT FROM AUTHOR]

Allergen-specific IgE production is the central event in the pathogenesis of atopic disorders and increases in specific IgE serum antibodies are an indicator of immediate hypersensitivity responses in humans and in animal models of allergy. Consequently, accurate and user-friendly methods are needed to measure serum levels of allergen-specific IgE. This review examines historical and recent developments in in vivo and in vitro methods for the detection of allergen-specific IgE in humans and in animal models. Routinely, in vitro methods such as enzyme-linked immunosorbant assays or radioallergosorbant tests and in vivo methods such as the skin prick test (SPT) for humans and the passive cutaneous anaphylaxis assay (PCA) used in animals are utilized to detect allergen-specific IgE. While in vivo assays are usually more accurate than in vitro assays since they provide a functional readout of IgE activity, they are relatively costly and require considerable expertise. On the other hand in vitro assays are limited by the fact that the amount of allergen-specific serum IgG exceeds IgE antibody by several orders of magnitude, resulting in competition for allergen binding. Consequently, methods that use allergen as a direct capture step are limited by the availability of free allergen binding sites for IgE. In order to circumvent this problem, in vitro methods usually require prior depletion of IgG or use high amounts of allergen in order to facilitate availability of free binding sites for IgE detection. Clearly, these approaches are limited for small sample volumes and allergens that are in short supply. New methods such as protein microarray could potentially overcome this problem by providing high allergen concentrations in a relatively small reaction volume. Currently, in vitro methods are rarely used in isolation for prognosis but are used primarily to complement the information obtained from in vivo assays. With the emergence of new technologies it is conceivable that in vitro assays may in the future replace in vivo assays, however until then in vivo assays remain the gold standard of allergen-specific IgE detection. [ABSTRACT FROM AUTHOR]

Use of enzymes in cosmetic products is novel and the safety of these products is not well understood. The safety of a prototype enzyme-containing body moisturizer lotion was tested via measures of skin compatibility and potential to induce protease-specific IgE antibody in a clinical study. Female, atopic subjects (n = 1,100) used body lotion containing 100 ppm protease (Y217L BPN′) for 5 consecutive days per month, for 18 months. Regular lotion was used the remaining days of each month. Skin evaluation and skin prick tests (SPT) were conducted every 3 months. Measures of skin hydration were made in a subset of subjects at 3-month intervals: skin biopsies occurred at baseline and at the first 3-month timepoint. Serum from SPT positive subjects was tested for specific IgE in an immunoCAP assay. Clinical evaluation and histopathology showed no skin irritation and increased hydration of the skin over time. Three of 864 subjects completing the study developed IgE antibody to the enzyme: 1 subject after 6 months product use and 2 subjects after 15 months product use. A fourth subject was found with IgE antibody 3 months after study termination. None had allergic symptoms associated with product use. Intermittent exposure to a low level of protease enzyme in a body lotion led to the development of specific IgE antibody in 0.46% of subjects. While this study showed favorable skin compatibility of the protease containing lotion, the occurrence of allergic antibody to the enzyme was unacceptable for product commercialization. [ABSTRACT FROM AUTHOR]