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PubMed1986

Maternal alloimmune reactions towards the murine conceptus and graft-versus-host reaction (GVHR). II. Inhibition of priming by placental extracts.

Gestation can induce a priming for a GVHR towards paternal strain antigens, although this priming is significantly lower than the one induced by experimental immunization. A role has been sought for placental substances in decreasing this priming through immunomodulation. BALB/c (H-2d) spleen cells do not usually induce a systemic, lethal GVHR in DBA/2 (H-2d) newborn mice except when the donors are preimmunized with DBA/2 cells. Placental extracts (as well as RPMI medium or liver extracts used as controls) were added to DBA/2 cells injected into BALB/c mice used as cell donors for GVH induction. The latter's spleen cells, harvested on day 6 after immunization, were used for systemic and local GVHR. In the systemic assay (lethal effect on DBA/2 newborn mice injected i.v. with BALB/c spleen cells) a significant protection was observed. In the local assay (popliteal lymph node assay in F1 hybrids injected with BALB/c spleen cells into the foot-pad) a highly significant inhibition of priming was detected in recipients injected with spleen cells from placental extract-treated donors. The stimulation index was even lower than that obtained with unprimed BALB/c spleen cells. The same type of local GVHR in (CBA/Ca X A/J) F1 hybrids injected with CBA cells led to similar results. In both situations (systemic and local GVHR) the observed inhibition was found to be specific to the priming cell strain. These results support the working hypothesis that placental substances are able to modify the systemic response of an organism towards both H-2 and non-H-2 alloantigens.

Animals↗

PubMed2007

Detection of autoimmunity by pharmaceuticals.

Despite the important health and economic impact of autoimmunogenicity or allergenicity by pharmaceuticals models to detect such adverse effects are not available yet. The most important reason for this is the related complex interplay of multiple factors, for which reason these adverse effects are also referred to as idiosyncratic in nature. Moreover, clinical effects are quite diverse, and involve both organ-specific and systemic effects, including a diversity of skin diseases. Because of its complexity on the one hand and the fundamental knowledge on certain particular mechanistic effects it may be more relevant to design a rationalistic toolbox of test models from which a predictive strategy can be composed. Since one mechanistic aspect centers around T cell sensitization a straightforward lymph node assay such as the reporter antigen-popliteal lymph node assay (RA-PLNA) would fit in such a toolbox. This RA-PLNA holds a strong promise to distinguish sensitizing and/or neoantigen-forming capacity of low molecular weight pharmaceuticals. In addition, from the pharmacokinetic point of view a rationalistic toolbox should also contain oral exposure models with immunological read out parameters in normal or in genetically predisposed animal strains. This review focuses on these two categories of candidate test methods, PLNA and oral exposure models, and proposes to use these in tandem in order to predict the hazard of induction of allergy or autoimmune phenomena by new pharmaceutical candidates.

Animals↗

PubMed1996

Local popliteal lymph node reactions to hexachlorobenzene and pentachlorobenzene: comparison with systemic effects.

The effects of the presumed autoimmunogenic chemical hexachlorobenzene (HCB), and the closely related non-autoimmunogenic pentachlorobenzene (PCB) in the local popliteal lymph node assay (PLNA) were investigated. To that end 1-5 mg of HCB, equimolar amounts of PCB or the vehicle only, were injected into the hind footpads of rats or mice, and the reaction in the draining lymph node was evaluated on days 7 and 21 after injection. PLN were isolated, weighed, and cell suspensions were prepared to determine PLN cell numbers, and antibody production of PLN cells with an ELISPOT assay or a line immunoassay. The extent of the lymphoproliferative effect was examined by detection of proliferating cells with the BrdU method, and by measurement of paracortex and follicle areas, by combined immunohistochemistry and morphometry of PLN cryosections. We demonstrate here that HCB elevated PLN weights and cell numbers of the rat PLN, by day 7 after injection, but no elevation of antibody production in the PLN. Moreover, HCB caused an enlargement of both the PLN paracortical and follicular areas, and an elevation of proliferating paracortical T cells. None of the HCB-induced effects were found on day 21. HCB caused the same effects in the mouse PLNA, but they tended to sustain at least until day 21. Hardly any of the HCB-induced changes were found when PCB was injected. Previously, we have shown that oral exposure of Wistar rats to HCB elevated the number of splenic T cells and B cells, but also the serum levels of (auto-)antibodies and the production of these antibodies in the spleen, which is thus only partly in accordance with the results of the local reaction to HCB described in this study. This seeming contradiction is discussed.

Animals↗

PubMed2003

Oxazolone and diclofenac-induced popliteal lymph node assay reactions are attenuated in mice orally pretreated with the respective compound: potential role for the induction of regulatory mechanisms following enteric administration.

The murine popliteal lymph node assay (PLNA) was examined as a preclinical assay with the potential to identify low-molecular-weight compounds (LMWCs) that are likely to be associated with immune-mediated drug hypersensitivity reactions (IDHRs) in humans. We hypothesized that the contact sensitizer oxazolone (OX) would cause a strong PLN reaction in naive mice and that the PLN reaction would be attenuated in mice orally pretreated with OX due to the induction of oral tolerance. In naive mice, OX induced a strong PLN reaction and caused dose-dependent increases in PLN size, weight, cellularity, percentage of CD4(+) PLN T cells, and percentage of PLN B cells, with a concomitant decrease in the percentage of CD8(+) PLN T cells. Next, the PLNA was conducted in mice gavaged three times with either OX or vehicle alone (olive oil). Mice pretreated with OX had suppressed PLN reactions following the footpad injection of OX (decrease in PLN size, weight, and cellularity), which was associated with an increase in the percentage of PLN CD8(+)T cells. In contrast, oral pretreatment with OX had no observable effect on the PLN reaction induced following footpad injection of the irrelevant hapten dinitrochlorobenzene (DNCB). Adoptive transfer studies were conducted to examine the mechanism of PLN hyporesponsiveness. It was found that either (1) unfractionated splenocytes or (2) purified CD8(+) splenocytes, but not (3) purified CD4(+) splenocytes isolated from mice gavaged with OX adoptively transferred PLN suppression to naive BALB/c mice. Because OX is not a pharmaceutical, we also examined the NSAID diclofenac (DF) (Voltaren). Like OX, DF caused dose-dependent increases in PLN size, weight, and cellularity in naive mice. Furthermore, like OX, the diclofenac-induced PLN reaction was attenuated in mice that had been orally pretreated three times with DF. However, splenocytes from mice orally treated with DF were not able to adoptively transfer PLN hyporesponsiveness. Collectively, these observations demonstrate that both OX and DF are potent immunostimulators in the PLNA. As importantly, these results demonstrate that the immunostimulating potential of OX and DF in the PLNA is significantly decreased in mice orally exposed to the respective drug, possibly due to the presence of a cellular mechanism of oral tolerance. For OX, the mechanism appears to involve, in part, CD8(+) T cells, whereas the mechanism(s) associated with PLN hyporesponsiveness using DF remain to be defined.

Adjuvants, Immunologic↗

PubMed2003

Immunomodulatory effects of tetrachlorobenzoquinone, a reactive metabolite of hexachlorobenzene.

Hexachlorobenzene (HCB) is an environmental pollutant that causes autoimmune-like effects in humans and rats. It is not completely clear whether T cells are involved and, if so, how they are stimulated after oral exposure to HCB. HCB as a rather inert chemical is not likely to bind covalently to macromolecules. The oxidative metabolite of HCB, tetrachlorobenzoquinone (TCBQ), which is in a redox equilibrium with tetrachlorohydroquinone (TCHQ), can bind to macromolecules, hence may form hapten-carrier complexes in vivo. We have assessed in the reporter antigen-popliteal lymph node assay whether HCB or TCHQ and TCBQ are able to induce a 2,4,6-trinitrophenyl (TNP) specific IgG1 response to the T cell-independent antigen TNP-Ficoll, which is indicative of neoantigen specific T cell help. To this end, these compounds and silica were injected into the footpad of Balb/c mice. Silica was included as an inert model compound, which causes autoimmune-like effects by activating macrophages. Seven days later, cell number and TNP specific antibody-secreting cells (ASC) in the popliteal lymph node (PLN) were determined. Furthermore, a secondary PLNA was performed to find out if TCHQ was capable of eliciting a memory response. Silica, TCHQ, and TCBQ, but not HCB, increased PLN cellularity and the number of IgM-producing ASC by ELISPOT. Both oxidative metabolites were able to induce the formation of germinal centers as assessed by immunohistochemistry and an IgG1 response to TNP-Ficoll. In the secondary PLNA, only mice primed with TCHQ and challenged with TCHQ together with TNP-Ficoll showed a significant increase in TNP specific IgG1 ASC. Present data show that TCHQ and TCBQ are capable of inducing neoantigen specific T cell help and that TCHQ can induce a compound specific memory response.

Adjuvants, Immunologic↗

PubMed2001

The popliteal lymph node assay: a tool for predicting drug allergies.

A considerable number of drugs is able to induce systemic hypersensitivity in man. Systemic hypersensitivity can be drug- or autoantigen-specific, but in either case a complex of immunological processes and predisposing factors are involved and it is rarely if ever noticed in standard toxicity testing. The popliteal lymph node assay (PLNA) is regarded a suitable test to screen for the immunostimulating ability of a chemical, which may indicate its immunosensitizing potential. The most simple, primary PLNA measures popliteal lymph node hyperplasia after subcutaneous injection of a chemical into the footpad of the hindpaw of a mouse or rat. In order to assess the involvement of T cells, and hence immunosensitizating potential of a chemical, anamnestic immune reactions to a chemical or its metabolite can be measured in previously exposed (and sensitized) animals or in naive animals that received an adoptive transfer of syngeneic T cells from previously exposed animals. In the recently introduced modified PLNA, defined reporter antigens TNP-OVA (T cell-dependent antigen) and TNP-Ficoll (T cell-independent antigen) are used to distinguish between sensitizing and non-sensitizing (IgG1-response or not to TNP-Ficoll, respectively) and between mere inflammatory and complete innocent (no IgG1-response to TNP-Ficoll and an IgG1-response or not to TNP-OVA, respectively) drugs. Results with about 130 compounds (drugs and environmental pollutants) with the various types of the PLNA show a good correlation with documented immunostimulating (both autoimmunogenic and allergic) potential and no false negative chemicals were detected if metabolism was considered. The PLNA awaits further validation before this test can be recommended as a tool for prediction of drug allergy.

Allergens↗

PubMedDate not supplied

Popliteal lymph node assay: facts and perspectives.

The popliteal lymph node assay (PLNA) derives from the hypothesis that some supposedly immune-mediated adverse effects induced by certain pharmaceuticals involve a mechanism resembling a graft-versus-host reaction. The injection of many but not all of these compounds into the footpad of mice or rats produces an increase in the weight and/or cellularity of the popliteal lymph node in the treated limb (direct PLNA). Some of the compounds known to cause these adverse effects in humans, however, failed to induce a positive PLNA response, leading to refinements of the technique to include pretreatment with enzyme inducers, depletion of CD4(+) T cells or additional endpoints such as histological examination, lymphocyte subset analysis and cytokine fingerprinting. Alternative approaches have been used to improve further the predictability of the assay. In the secondary PLNA, the test compound is injected twice in order to illicit a greater secondary response, thus suggesting a memory-specific T cell response. In the adoptive PLNA, popliteal lymph node cells from treated mice are injected into the footpad of naive mice; a marked response to a subsequent footpad challenge demonstrates the involvement of T cells. Finally, the reporter antigens TNP-Ficoll and TNP-ovalbumin are used to differentiate compounds that induce responses involving neo-antigen help or co-stimulatory signals (modified PLNA). The PLNA is increasingly considered as a tool for detection of the potential to induce both sensitization and autoimmune reactions. A major current limitation is validation. A small inter-laboratory validation study of the direct PLNA found consistent results. No such study has been performed using an alternative protocol. Other issues include selection of the optimal protocol for an improved prediction of sensitization vs autoimmunity, and the elimination of false-positive responses due to primary irritation. Finally, a better understanding of underlying mechanisms is essential to determine the most relevant endpoints. The confusion resulting from use of the PLNA to predict autoimmune-like reactions as well as sensitization should be clarified. Interestingly, most drugs that were positive in the direct PLNA are also known to cause drug hypersensitivity syndrome in treated patients. This observation is expected to open new avenues of research.

Adoptive Transfer↗

PubMed2004

Cytokine release does not improve the sensitivity and specificity of the direct popliteal lymph node assay.

The popliteal lymph node assay (PLNA) is being considered as a tool to predict the potential of drugs for inducing systemic autoimmune and hypersensitivity reactions. Despite the use of different technical approaches and the evaluation of over 130 compounds, the sensitivity and specificity of the PLNA are still debatable due to many false positive and negative responses. In this study, cytokine production was assessed as a possible endpoint to improve the direct (primary) PLNA. Diclofenac, imipramine, hydralazine, glafenin and minocycline were tested using the classical procedure. TH1 cytokines (IL-2 and IFN-gamma), TH2 cytokines (IL-4 and IL-5) and pro-inflammatory cytokines (IL-6, TNF-alpha, monocyte chemoattractant protein-1 (MCP-1), IL-12p70 and IL-10) were measured in the serum and in suspensions of popliteal lymph node cells of female Balb/c mice by flow cytometry 7 days after drug administration. Only diclofenac and imipramine induced a cellularity index above 5 (considered as a positive response). Of the five tested drugs, only diclofenac induced a slight increase in TH1 cytokines, but there were no effects on TH2 cytokine production whatever the drug tested. Diclofenac increased the production of pro-inflammatory cytokines, whereas the production of MCP-1 was increased by minocycline and decreased by imipramine. No changes in serum cytokine levels were evident. These results suggest that measuring cytokine release is unlikely to improve the sensitivity and specificity of the direct PLNA.

Animals↗

PubMedDate not supplied

Acetone in drinking water does not modulate humoral immunity in mice as measured by the antibody, plaque-forming cell assay.

It has been reported that the repeated topical, nonoccluded application of acetone may modulate antibody production in mice, thus producing humoral immunosuppression. However, the evaporative loss expected following nonoccluded dermal application of acetone makes the systemic effect seem unlikely. This study was designed to investigate the immunotoxicity potential of acetone in mice following a more direct systemic route of dosing via drinking water for 28 days. CD-1 male mice consumed average daily acetone doses of 121, 621 or 1144 mg/kg/day. The antibody, plaque-forming cell (AFC) assay was performed to measure the T cell-dependent, anti-sheep red blood cell immunoglobulin M (IgM) response, and hematology and thymus weights were evaluated to provide additional insight into the potential effects to the immune system. Body weights, white blood cell (WBC), numbers, red blood cell (RBC) counts, and hemoglobin and hematocrit levels showed no treatment-related effects at any dose of acetone. Eosinophil percentages were variable but also showed no dose-related trends. Spleen and thymus weights were not statistically different from controls and there were no effects on spleen cellularity or AFC response as a result of acetone administration. The AFC responses ranged from 1088 to 1401 AFCs/10(6) splenocytes and were not statistically different from controls (1277 AFCs/10(6) cells). Mice treated with cyclophosphamide (20 mg/kg) on days 25 to 28 demonstrated a 94% reduction in AFC/10(6) cells. Thus, the direct systemic administration of acetone did not produce evidence for immunotoxicity in CD-1 mice and the no observed adverse effect level (NOAEL) in this study was determined to be 1144 mg/kg/day.

Acetone↗

PubMed2001

Assessment of preferential Th1 or Th2 induction by low-molecular-weight compounds using a reverse transcription-polymerase chain reaction method: comparison of two mouse strains, C57BL/6 and BALB/c.

The aim of this study was to examine whether the RT-PCR method for various Th1/Th2 cytokines is appropriate for determination of response to allergens using C57BL/6 and Balb/c mice, which are known to preferentially demonstrate Th1 and Th2 responses, respectively. To this end, both strains of mice were sensitized by skin painting with the contact allergen dinitrochlorobenzene (DNCB) or the respiratory allergen trimellitic anhydride (TMA). We used the sensitizing protocol adopted by Kimber and coworkers (Toxicology 103, 63-73, 1995). At various time points after the last application, the levels of mRNA expression for Th1-type cytokines IFN-gamma, IL-18, and IL-12p40, as well as receptor IL-18R, and the Th2-type cytokine IL-4 and the receptor ST2L, in lymph nodes were measured. The results suggest that differential expression of IL-12p40 and IL-4 mRNA after 24 h allows clear discrimination between DNCB and TMA in C57BL/6 mice, more obviously than in Balb/c mice. Furthermore, to examine this method, C57BL/6 mice were exposed to OXA, DNFB, and TNCB (Th1-predominant allergens) or PA, TDI, and MDI (Th2-predominant allergens). Elevation of IL-12p40 expression was significant with the Th1 inducers, while the level of IL-4 was higher with Th2-predominant allergens. The results of the present study demonstrate, for the first time, that differential expression of IL-12p40 and IL-4 in C57BL/6 mice may be useful as a parameter for assessing influence of contact and respiratory allergens.

Allergens↗

PubMed2001

Intraoperative decrease in pulse oximeter readings following injection of isosulfan blue.

PURPOSE: Sentinel lymph node mapping, involving injection of isosulfan blue dye around a tumour, is beginning to be used in patients with carcinoma of the breast. Absorption of the dye into the circulation may interfere with pulse oximetry, causing falsely low readings. This report describes changes in pulse oximeter readings following injection of isosulfan blue for sentinel lymph node mapping in a patient with carcinoma of the breast. CLINICAL FEATURES: An 83-yr-old female patient underwent sentinel node biopsy of the axilla followed by partial mastectomy for carcinoma of the left breast. Isosulfan blue was injected in the area of the tumour in the left breast. The SpO2 began to decrease 15 min after dye injection, reaching a nadir of 89-90% 30 min after injection. Arterial blood gas analysis showed normal arterial partial pressure of oxygen. Pulse oximeter readings did not return to normal until more than six hours after dye injection. CONCLUSION: Review of the literature reveals a small number of case reports of similar occurrences of low pulse oximeter readings following injection of isosulfan blue or patent blue dye for lymphatic mapping. Data from these reports and the case described here suggest that the latency, magnitude and duration of effect on pulse oximeter readings following injection of these dyes is highly variable. It is important to rule out other causes of low pulse oximeter readings when this effect occurs; normal oxygenation can be verified with arterial blood gas analysis. Co-oximetry can be done to rule out methemoglobinemia as a cause of decreased SpO2.

Adenocarcinoma↗

PubMed1992

The effect of age, sex and breeding on graft versus host reactivity of spleen cells from C57BL mice.

Spleen cell graft versus host (GvH) reactivity was determined in male and female, either virgin or breeder, C57BL mice from 3 to 24 months of age. The GvH reaction was assessed by a local popliteal lymph node assay and by a splenomegaly test for a systemic reaction. Although the GvH reactivity declines progressively with age in both sexes the virgin female response was greater than that of males throughout the period of 6-18 months of age. Two-year-old mice of both sexes were practically unable to mount a GvH reaction. No differences were evident in aging female reactivity after one or two syngeneic pregnancies. On the other hand, 3 or more consecutive pregnancies resulted in enhanced GvH reactivity of 12-24-month-old females, which responded comparably to young virgin mice. This long-lasting immunopotentiating effect of multiparity was similar after 3-4 and 8-9 pregnancies. The possible role of developing foetuses on the maintenance of high GvH reactivity in breeder females is suggested.

Aging↗

PubMed2005

A comparative study of the sensitivity of the 3-induction and 9-induction Buehler test procedures for assessing skin sensitisation potential.

Assessment of skin sensitization potential is a mandatory requirement for the registration or notification of most types of chemicals and products. Until recently, two methods using the guinea pig as test model were the most widely accepted; the guinea pig maximisation test and the Buehler test. In the case of agrochemical formulations, which constitute the final end use product in contact with operators, industry and also some regulatory authorities consider the Buehler method more appropriate as the methodology is more relevant to likely exposure in the field. However, certain European regulatory authorities have become concerned about the sensitivity of the Buehler test for this purpose and have requested that a modified method is used in which additional applications of test materials are used during the induction phase of the protocol (a total of 9 rather than the normal 3). This study was designed to assess whether this modification was justified. Six reference substances (formaldehyde, alpha-hexylcinnamaldehyde, fragrance mix, thimerosal, mercaptobenzothiazole and phthalic anhydride); all mild to moderate skin sensitizing chemicals, were assessed in a study, which compared the use of 3 and 9 induction applications. The results of this study demonstrated that, although most of these sensitisers were detected by both protocols, the modified method (9 induction applications) was no more sensitive than the standard method (3 induction applications). As the modified protocol is also potentially more stressful to the animals, it is concluded that the use of additional induction applications in the Buehler test cannot be justified from either a scientific or an animal welfare perspective.

Allergens↗

PubMed2005

An alpha,beta-unsaturated oxime identified as a strong contact allergen. Indications of antigen formation via several pathways.

The aim of this study was to examine the possible skin sensitizing effect of oximes, employing an alpha,beta-unsaturated oxime as the model compound. Oximes are not frequently used as biologically active compounds. However, they have been shown to possess both anti-inflammatory and anti-allergic activities. Furthermore, in a recent study, a number of oximes and oxime-ethers of hydroxylated benzaldehydes and acetophenones were found to be powerful antioxidants suggested to be used in consumer products such as cosmetics and food. Although there are only few reports on the sensitizing effect of oximes, their ability to be hydrolyzed to the corresponding ketones or aldehydes makes them potential contact allergens. The oxime investigated in this study was demonstrated to be a strong contact allergen in both mice and guinea pigs, capable of sensitize the control animals after only one dermal exposure. In order to elucidate the mechanisms for the formation of the complete antigen, a variety of analogues with different reactivity were tested. The results indicate that alpha,beta-unsaturated oximes can react with proteins via several different pathways. Most likely, a metabolic transformation is involved. Due to the strong allergenic effect of the oxime investigated, we strongly advise against the use of such oximes in consumer products until a better understanding of their interactions with biological macromolecules has been obtained.

Allergens↗

PubMed2004

Identification of contact and respiratory sensitizers using flow cytometry.

Identification of the chemicals responsible for respiratory and contact allergies in the industrial area is an important occupational safety issue. This study was conducted in mice to determine whether flow cytometry is an appropriate method to analyze and differentiate the specific immune responses to the respiratory sensitizer trimellitic anhydride (TMA) and to the contact sensitizer dinitrochlorobenzene (DNCB) used at concentrations with comparable immunogenic potential. Mice were exposed twice on the flanks (days 0, 5) to 10% TMA or 1% DNCB and challenged three times on the ears (days 10, 11, 12) with 2.5% TMA or 0.25% DNCB. Flow cytometry analyses were conducted on draining lymph node cells harvested on days 13 and 18. Comparing TMA and DNCB immune responses on day 13, we found obvious differences that persisted for most of them on day 18. An increased proportion of IgE+ cells correlated to total serum IgE level and an enhancement of MHC II molecule expression were observed in the lymph node B lymphocytes from TMA-treated mice. The percentage of IL-4-producing CD4+ lymphocytes and the IL-4 receptor expression were clearly higher following TMA exposure. In contrast, higher proportions of IL-2-producing cells were detected in CD4+ and CD8+ cells from DNCB-treated mice. Both chemicals induced a significant increase in the percentage of IFN-gamma-producing cells among CD8+ lymphocytes but to a greater proportion following TMA treatment. In conclusion, this study encourages the use of flow cytometry to discriminate between contact and respiratory sensitizers by identifying divergent expression of immune response parameters.

Administration, Inhalation↗

PubMed2005

Cytokine mRNA profiles for isocyanates with known and unknown potential to induce respiratory sensitization.

Isocyanates are low-molecular-weight chemicals implicated in allergic asthmatic-type reactions. Identification of chemicals likely to cause asthma is difficult due to the lack of a validated test method. One hypothesis is that differential cytokine induction (Th1 versus Th2 profiles) in the draining lymph node following dermal application can be used to identify asthmagens and distinguish them from contact allergens. In this study, we compared the cytokine mRNA profiles of six chemicals: toluene diisocyanate (TDI), diphenylmethane-4,4'-diisocyanate (MDI), dicyclohexylmethane-4,4'-diisocyanate (HMDI), isophorone diisocyanate (IPDI), p-tolyl(mono)isocyanate (TMI), and meta-tetramethylene xylene diisocyanate (TMXDI). Whereas TDI and MDI are well-known respiratory sensitizers, documentation for HMDI, IPDI, TMI, and TMXDI is limited, but suggests that HMDI and IPDI may have respiratory sensitization potential in humans and TMI and TMXDI do not. Following dermal exposure of BALB/c mice, all six isocyanates induced cytokines characteristic of a Th2 response. Although LLNAs suggested that the doses chosen for the RPA were immunologically equivalent, the isocyanates tested differentiated into two groups, high responders and low responders. However, two of the low responders (TMI and TMXDI) were further tested and induced higher levels of Th2 cytokine message than dinitrochlorobenzene (not an asthmagen). Further study of these chemicals is needed to determine whether the Th2 cytokine responses observed for these low responders is predictive of asthmagenic potential or represents an insufficient signal.

Allergens↗

PubMed2006

Investigation of the immunogenicity of diclofenac and diclofenac metabolites.

Oral administration of the non-steroidal anti-inflammatory drug diclofenac (DCF) is associated with a high incidence of adverse drug reactions, some of which are thought to be mediated by the immune system. It has been proposed that metabolic activation of DCF and covalent binding to protein generates an antigenic determinant that stimulates immune cells; however, the nature of the metabolite remains ill-defined. The aim of this study was to synthesize and evaluate the antigenic potential of DCF metabolites in the mouse. DCF and DCF metabolites were administered via subcutaneous injection over a 5-day period to BALB/C strain mice to induce immune activation. Proliferation was measured by the addition of [(3)H] thymidine to ex vivo isolated draining auricular lymph node cells. Results were compared with those provoked by exposure to 2,4-dinitrochlorobenzene. Lymph node activation was observed following treatment with 2,4-dinitrochlorobenzene, 5-hydroxy DCF quinoneimine and 4'-hydroxy DCF quinoneimine, but not DCF acyl glucuronide or DCF itself. Interestingly, lymph node cells from 5-hydroxy DCF treated mice were also found to proliferate, when compared with cells from vehicle-treated mice, while 4'-hydroxy DCF did not stimulate lymph node cell activation. The reactivity of 5-hydroxy DCF quinoneimine was confirmed by synthesis and characterization of an N-acetyl cysteine adduct. These data show that formation of 5-hydroxy DCF and subsequent autoxidation provides an antigenic determinant for immune cell activation in the mouse.

Animals↗

PubMed2001

Pre-clinical methods for detecting the hypersensitivity potential of pharmaceuticals: regulatory considerations.

Immune-based systemic hypersensitivities account for a significant number of adverse drug reactions. There appear to be no adequate nonclinical models to predict systemic hypersensitivity to small molecular weight drugs. Although there are very good methods for detecting drugs that can induce contact sensitization, these have not been successfully adapted for prediction of systemic hypersensitivity. Several factors have made the development of adequate models difficult. The term systemic hypersensitivity encompases many discrete immunopathologies. Each type of immunopathology presumably is the result of a specific cluster of immunologic and biochemical phenomena. Certainly other factors, such as genetic predisposition, metabolic idiosyncrasies, and concomitant diseases, further complicate the problem. Therefore, it may be difficult to find common mechanisms upon which to construct adequate models to predict specific types of systemic hypersensitivity reactions. There is some reason to hope, however, that adequate methods could be developed for at least identifying drugs that have the potential to produce signs indicative of a general hazard for immune-based reactions.

Animals↗