High allergen-specific serum immunoglobulin E levels in nonatopic West Highland white terriers

Human and canine atopic dermatitis (AD) share an association with IgE specific to environmental allergens, but few studies have evaluated serum allergen‐specific IgE in nonatopic dogs. This study compared serum allergen‐specific IgE levels in 30 atopic and 18 nonatopic West Highland white terriers. Atopic dermatitis was confirmed using standard criteria. Nonatopic dogs were over 5 years of age and had no clinical signs or history of AD. Serum allergen‐specific IgE levels were measured with Allercept^® IgE ELISAs using a 48‐allergen Australian panel. Positive reactions were defined as ≥150 ELISA absorbance units. Intradermal tests were performed in 16 atopic dogs, either at the time of or at various times prior to serum collection. In atopic dogs, the most common positive ELISA and intradermal test results were to Dermatophagoides farinae (11 of 30 dogs), but there were no statistically significant correlations between results from the two methods for any allergen. In nonatopic dogs, multiple high‐positive ELISA reactions were reported to 45 of 48 allergens, most commonly D. farinae and Tyrophagus putrescentiae (17 of 18 dogs each). Positive ELISA results in nonatopic dogs were statistically significantly higher than those in atopic dogs for 44 of 48 allergens, including two allergens (D. farinae and Dermatophagoides pteronyssinus) commonly regarded as significant in canine AD. In conclusion, positive allergen‐specific IgE ELISAs were not specific for canine AD, and high allergen‐specific IgE levels were seen in nonatopic dogs. The clinical significance of this and whether it characterizes a protective phenotype is unclear.     

Serum antibodies to Malassezia yeasts in canine atopic dermatitis

Significant numbers of humans with atopic dermatitis develop Malassezia-specific IgE. Immediate skin-test reactivity to Malassezia has been demonstrated in atopic dogs. The aim of this study was to compare the serum IgG and IgE response to Malassezia in atopic dogs with and without clinical evidence of Malassezia dermatitis and/or otitis, nonatopic dogs with clinical evidence of Malassezia dermatitis and/or otitis and healthy dogs. Cytology was used to diagnose clinically significant Malassezia dermatitis and otitis. Contact plate cultures confirmed the validity of this technique. Reproducible enzyme-linked immunosorbent assays for Malassezia-specific IgG and IgE in canine serum were established. Atopic dogs had significantly higher serum IgG and IgE levels than either healthy dogs or nonatopic dogs with clinical evidence of Malassezia dermatitis and/or otitis. There was no significant difference in IgG and IgE levels between atopic dogs with and without clinical evidence of Malassezia dermatitis and/or otitis. The implications of these findings in the pathogenesis and management of canine atopic dermatitis are discussed.     

Comparison between an intradermal skin test and allergen-specific IgE-ELISA for canine atopic dermatitis

The aim of this study was to compare the results of an intradermal skin test (IDST) with those of an allergen-specific IgE-ELISA in 210 dogs with atopic dermatitis. All the dogs had a clinical diagnosis of atopic dermatitis and underwent an IDST. The sera of all dogs were analysed for allergen-specific IgE by ELISA using the monoclonal antibody D9 against dog IgE. IDST was used as the standard assay. In both methods, the following antigens provided a positive test result: Dermatophagoides farinae, Acarus siro, Tyrophagus putrescentiae, ragweed, mugwort and Lepidoglyphus destructor. ELISA had an overall sensitivity of 82.4% and an overall specificity of 93.8%. The overall accuracy of the ELISA was 91.3%. The evaluated monoclonal D9 ELISA was found to be a reliable tool for the diagnosis of those allergens that cause clinical atopy, and can be recommended for use in dogs when immunotherapy is a therapeutic option.     

Early exposure to probiotics in a canine model of atopic dermatitis has long-term clinical and immunological effects

Probiotics modulate the immune response and may have protective effects against atopic dermatitis (AD). Clinical trials using dogs with spontaneous disease are limited by confounding factors such as different diets, environments and sensitizations while a more controlled evaluation is possible using experimental models. A validated model of canine AD showed that early exposure to Lactobacillus rhamnosus GG (LGG) significantly decreases allergen-specific IgE and partially prevents AD in the first 6 months of life. This study is a follow-up three years after discontinuation of LGG. Clinical signs were evaluated after allergen challenge with ragweed, timothy, Dermatophagoides farinae. Allergen-specific IgE, IL-10 and TGF-β were measured on the 1st day of challenge, before allergen exposure. Normal dogs were included as controls. Analyses included seven dogs in the non-probiotic and nine in the probiotic litter. For clinical scores, a 2-Group × 9-Time Analysis of Variance showed significant effects of group (p=0.0003, probiotic相似文献   

Dermatophagoides farinae-specific IgG subclass responses in atopic dogs undergoing allergen-specific immunotherapy

Atopic dermatitis (AD) is thought to be caused by immunologic abnormalities expressed as a Th1/Th2 cytokine imbalance in both humans and dogs. Several studies have focused on the therapeutic effects of IFNγ in human AD with successful results; however, the mechanism of action of IFNγ is not fully understood. We investigated the effect of recombinant canine interferon gamma (rCaIFNγ) on 10 dogs with AD and evaluated the ratio of IL-4 mRNA to IFNγ mRNA in peripheral blood mononuclear cells, serum total IgE levels, and histological changes in skin. After six injections of rCaIFNγ over a span of 2 weeks, seven of the 10 dogs showed improvement, and six of these seven dogs exhibited decreased IL-4:IFNγ mRNA ratios. Two of the three cases that did not improve had increased IL-4:IFNγ mRNA ratios. Total serum IgE levels were significantly decreased in nine of 10 cases. The number of IgE-positive cells detected by immunostaining and the number of mast cells in skin biopsy samples were decreased. A reduction of epidermal cell layers was demonstrated by histopathology after treatment. These results demonstrated that rCaIFNγ may be a novel safe and effective therapeutic option for the treatment of canine AD, and the mechanism of action of rCaIFNγ may be related to the modulation of Th2 cytokines to Th1 cytokines with the reduction of serum IgE production.
Funding: Self-funded.     

Tolerability and clinical efficacy of oral immunotherapy with house dust mites in a model of canine atopic dermatitis: a pilot study

Atopic dermatitis (AD) is a chronic, life‐long disease. In humans, immunotherapy (IT) is the only treatment that can alter the course of AD. Oral IT is appealing owing to the ease of administration and the potential for increased compliance. The purposes of this study were to investigate the tolerability, clinical efficacy and effects on allergen‐specific IgE of oral IT using a canine AD model. Thirteen atopic beagles sensitized to house dust mites (HDMs) were randomly divided into two groups. One group received daily oral doses of HDMs while the other group received vehicle only for 7 months. The investigator evaluating the dogs was blinded to the allocation of treatments. Prior to and after 2 and 7 months of IT, dogs were challenged daily with HDMs for 3 days concurrently, and clinical signs were scored using a modified Canine Atopic Dermatitis Extent and Severity Index (CADESI). Prior to and at completion of oral IT, serum was collected for measurement of allergen‐specific IgE. Oral IT was well tolerated, and no adverse effects were noted. Analysis of variance showed no significant effect of time, group and group × time interaction for CADESI scores. In addition, there were no significant differences in allergen‐specific IgE levels. In conclusion, it appears that oral administration of HDMs is well tolerated in these atopic beagles but that this protocol was not sufficient to induce clinical improvement. Further, longer‐term studies will be necessary to explore the potential of oral IT in veterinary medicine.     

Total IgE and allergen-specific IgE and IgG antibody levels in sera of atopic dermatitis affected and non-affected Labrador- and Golden retrievers

Canine atopic dermatitis (CAD) is an allergic skin disease associated with IgE and IgG antibodies (Ab) to environmental allergens. The aim of this study was to determine which other factors influence serum Ab levels in CAD-affected and non-affected dogs as this has only been poorly investigated in dogs so far. Total and allergen-specific IgE levels and Dermatophagoides farinae (DF)-specific IgG1 and IgG4 were measured by ELISA in sera of 145 CAD-affected and 271 non-affected Labrador- and Golden retrievers. A multivariable logistic regression analysis including the factors age, breed, gender, castration, clinical CAD status and allergen-specific immunotherapy (ASIT) was performed. Golden retrievers had more frequently total (OR=1.87, 95% CI=1.26-2.87, p<0.01) and specific IgE levels above the threshold value than Labrador retrievers, suggesting that genetic factors influence IgE levels in dogs. Castration was generally associated with low Ab levels (OR=0.43-0.65, p<0.05). Surprisingly, dogs with CAD did not have increased odds for high IgE against any of the allergens tested. ASIT with DF was associated with high DF-specific IgG1 (OR=4.32, 95% CI 1.46-12.8, p<0.01) but was not associated with DF-specific IgG4 or decreased IgE levels. Further studies are needed to understand the role of allergen-specific IgE in CAD and of IgG1 in ASIT.     

The ACVD task force on canine atopic dermatitis (XXIV): allergen-specific immunotherapy.

Allergen-specific immunotherapy (ASIT) has been used for years to treat dogs with atopic dermatitis (AD) and humans with atopic diseases. The efficacy of ASIT has been well documented for humans with respiratory atopic diseases and stinging insect allergy, but its effectiveness seems more controversial for patients with AD. In spite of insufficient evidence derived from randomized controlled trials, multiple open studies and a large body of clinical observations suggest that ASIT is effective in controlling the clinical signs of dogs with AD. As a result of the scarcity of evidence from controlled trials, the true efficacy of ASIT, and the optimal protocols for allergen dose and frequency of injection are currently unknown. Allergen-specific immunotherapy nevertheless may be included in the treatment of canine AD because of its potential advantages and limited disadvantages compared to other forms of therapy. There is no evidence, however, for the preference of any specific treatment protocol. The predictive value of historical, clinical and immunologic features related to the efficacy of ASIT in dogs with AD are discussed in this paper. Adverse reactions, and the requirements for monitoring of patients receiving ASIT, then are reviewed and detailed. Finally, this review highlights aspects of ASIT where further research and controlled studies are needed.     

Humoral measurement of type-1 hypersensitivity reactions to a commercial Malassezia allergen

Malassezia pachydermatis is considered to be a contributing factor to canine atopic dermatitis (AD). The purpose of this study was to investigate the humoral response to a commercially produced M. pachydermatis extract. Fifteen atopic dogs with Malassezia overgrowth on the skin (MD), 16 atopic dogs without MD, three atopic dogs with overgrowth of Malassezia in the ears only (MO), and 12 normal dogs were intradermally tested with M. pachydermatis extract at 50, 100, 250, 500, 1000, 2000 and 4000 PNU mL(-1). All dogs were evaluated cytologically by cutaneous tape strip and bilateral ear exudate sampling to determine presence of MD or MO. Each had serum evaluated for anti-Malassezia IgE using three Malassezia extracts with an ELISA assay. The irritant threshold concentration at which healthy nonatopic dogs ceased to react was 1000 PNU mL(-1). There was a significant difference in intradermal test reactivity between the atopic groups. At this dilution, 93% (14/15) of the atopic MD group, 31% (5/16) of the atopic group without MD or MO, and 100% (3/3) of the atopic MO only group reacted. There were no significant differences in the serum IgE levels as measured by the Greer ELISA assay, between any groups using any of the three extracts. These results support that Greer's M. pachydermatis extract is useful for intradermal testing of dogs with an allergic phenotype, and that atopics with MD are more likely to have a type-1 Malassezia hypersensitivity than those without. The ELISA assay may require further development in order to be useful for the diagnosis of Malassezia hypersensitivity.     

Interleukin‐31: its role in canine pruritus and naturally occurring canine atopic dermatitis

Background – Interleukin‐31 (IL‐31) is a member of the gp130/interleukin‐6 cytokine family that is produced by cell types such as T helper 2 lymphocytes and cutaneous lymphocyte antigen positive skin homing T cells. When overexpressed in transgenic mice, IL‐31 induces severe pruritus, alopecia and skin lesions. In humans, IL‐31 serum levels correlate with the severity of atopic dermatitis in adults and children. Hypothesis/Objective – To determine the role of IL‐31 in canine pruritus and naturally occurring canine atopic dermatitis (AD). Animals – Purpose‐bred beagle dogs were used for laboratory studies. Serum samples were obtained from laboratory animals, nondiseased client‐owned dogs and client‐owned dogs diagnosed with naturally occurring AD. Methods – Purpose‐bred beagle dogs were administered canine interleukin‐31 (cIL‐31) via several routes (intravenous, subcutaneous or intradermal), and pruritic behaviour was observed/quantified via video monitoring. Quantitative immunoassay techniques were employed to measure serum levels of cIL‐31 in dogs. Results – Injection of cIL‐31 into laboratory beagle dogs caused transient episodes of pruritic behaviour regardless of the route of administration. When evaluated over a 2 h period, dogs receiving cIL‐31 exhibited a significant increase in pruritic behaviour compared with dogs that received placebo. In addition, cIL‐31 levels were detectable in 57% of dogs with naturally occurring AD (≥13 pg/mL) but were below limits of quantification (<13 pg/mL) in normal, nondiseased laboratory or client‐owned animals. Conclusions – Canine IL‐31 induced pruritic behaviours in dogs. Canine IL‐31 was detected in the majority of dogs with naturally occurring AD, suggesting that this cytokine may play an important role in pruritic allergic skin conditions, such as atopic dermatitis, in this species.     

IgE is present on peripheral blood monocytes and B cells in normal dogs and dogs with atopic dermatitis but there is no correlation with serum IgE concentrations

Blood was collected from 29 dogs, 14 with atopic dermatitis (AD) and 15 controls. Total serum IgE was quantitated. Peripheral blood monocytes were harvested and labeled with leucocyte markers and anti-canine IgE before analysis by flow cytometry. There was no statistically significant difference between the atopic and control groups when the mean number of cells in the monocyte (CD14), antigen presenting cell (CD1c) or B cell (CD21) populations were examined. However, the variation in cell numbers was significant and much greater in the atopic group for CD1c and CD14 labeled cells. The mean percentage of double labeled cells, CD1c/IgE and CD14/IgE was significantly lower in the atopic population compared with the controls. More variation was observed in the numbers of monocytes of atopic dogs (CD14/IgE) and antigen presenting cells (CD1c/IgE) of control dogs. The mean percentage of B cells expressing IgE was 65 and 51% in the atopic and control groups respectively which is greater than that reported in humans. There was no statistically significant difference. Total serum IgE concentrations were similar in each group and did not correlate with cell bound IgE in any of the leucocyte populations studied. Canine AD is associated with more variability in circulating monocyte numbers and lower numbers of monocytes expressing IgE than control dogs. Unlike in humans, there is no correlation between circulating and cell bound IgE. Furthermore, high levels of IgE in the dog may be related to a greater number of B cells in the circulation committed to IgE production.     

FC-38 Efficacy of conjugated linoleic acid and black currant seed oil in the treatment of canine atopic dermatitis: a double-blinded, randomized, placebo-controlled study

The purpose of this study was to evaluate a combination of immunostimulatory bacterial DNA sequences and allergen-specific immunotherapy for the treatment of canine atopic dermatitis. Seven dogs with nonseasonal atopic dermatitis diagnosed by history, clinical signs and exclusion of differential diagnoses were included. All dogs had been on allergen-specific immunotherapy for at least 12 months with incomplete responses, were on additional antipruritic therapy and showed residual pruritus. Pruritus was marked by the owner on a visual analogue scale, lesions were determined by a clinician using the Canine Atopic Dermatitis Extent and Severity Index (CADESI), and concurrent medications were recorded before entering the study and after 14 weeks of treatment. Peripheral blood mononuclear cells were isolated and cultured; canine cytokine message for IFNγ, IL-4, TNF and IL-10 was quantitated using RT-PCR. A mixture of allergen extract and liposome-DNA complexes was injected intradermally at the beginning of the study and after 2, 4, 6, 10 and 14 weeks. CADESI, pruritus and medication scores, and cytokine messages at the beginning and end of the study were compared with a paired t -test. There were significant improvements in pruritus scores ( P  = 0.0277). Reductions in medication scores and CADESI were not statistically significant. IL-4 production decreased significantly ( P  = 0.0428); decreases in other cytokines were not significant. Although the number of dogs in this pilot study was small, the results warrant further investigation of a combination of immunostimulatory bacterial DNA sequences and allergen-specific immunotherapy for the treatment of canine atopic dermatitis.
Funding: Self-funded.     

Comparison of intradermal testing and serum testing for allergen-specific IgE using monoclonal IgE antibodies in 84 atopic dogs

OBJECTIVE: To compare an ELISA measuring serum allergen-specific IgE with intradermal skin testing in canine atopic dermatitis. PROCEDURE: Eighty-four dogs with the clinical diagnosis of atopic dermatitis underwent intradermal skin testing and serum testing for allergen-specific IgE. Tests were performed in a blinded fashion. Positive reactions were compared and the sensitivity and specificity of the serum test (using intradermal skin test as the standard) were determined overall and for individual allergen groups (grass pollens, weed pollens, tree pollens, house dust mites and fleas). RESULTS: The sensitivity of the ELISA overall was 90.4%. Evaluating the individual allergen groups, the sensitivity for dust mite hypersensitivity was 95.1%, for fleas 85.4%, for tree pollens 84.3%, for grass pollens 95.1% and for weed pollens 96.4%. The specificity was 91.6% overall, for dust mites 96.3%, for fleas 92.7%, for tree pollens 95.2%, for grass pollens 94% and for weed pollens 80.7%. CONCLUSION: The evaluated ELISA seemed reliable for the diagnosis of atopy in practice and can be recommended as a screening test prior to intradermal skin testing or for use in dogs when immunotherapy is not a therapeutic option.     

Serum immunoglobulin E concentrations in West Highland White Terrier puppies do not predict development of atopic dermatitis

Sera from 154 West Highland White Terrier puppies between 6 and 12 weeks of age were assayed for total IgE using a sandwich ELISA method. Development of clinical signs of atopic dermatitis in these dogs was monitored by use of an annual owner questionnaire, until the dog reached 3 years of age. Of 114 evaluated dogs, skin disease severe enough to warrant veterinary examination was reported in 52 (46%) during the three study years. A diagnosis of atopic dermatitis was made by the attending veterinarian in 28 dogs (25%). Certain litters had an especially high prevalence of apparently atopic dogs, consistent with the genetic predisposition towards atopy in this breed, but clear evidence of consistent heritability was not present. The median IgE concentration in 154 puppies at 6–12 weeks of age was 0.9 units mL⁻¹, with a skewed distribution. Significant ( P < 0.01) variation in serum IgE concentrations was observed between litters, with median serum IgE concentrations for a litter ranging from 0 to 27.7 units mL⁻¹. The median serum IgE concentration in puppies that later developed clinical signs of atopic dermatitis was not significantly different from that of puppies that remained healthy. There were no apparent correlations or significant differences found between serum IgE concentration as a puppy, parental history of skin disease, and subsequent emergence of clinical signs of atopic dermatitis. We conclude that early total serum IgE determinations seem to have little usefulness in predicting the later onset of atopic dermatitis in this breed.     

Characterisation of major and minor Dermatophagoides allergens in canine atopic dermatitis

Atopic dermatitis is a well-recognised chronic inflammatory skin disease of humans and dogs. Most atopic dogs are sensitised to Dermatophagoides mites. The aim of this study was to characterise allergens in different Dermatophagoides species using polyclonal and monoclonal antibodies to canine IgE. Western blots were prepared from crude extracts of D farinae, D pteronyssinus and D microceras, and purified group 1 and 2 allergens under reducing and non-reducing conditions. They were probed with sera from atopic (n = 33) and healthy (n = 27) dogs. There was no significant difference in the sensitivity or specificity between the polyclonal and monoclonal sera in detecting Dermatophagoides -specific IgE. Major allergens common to both D farinae and D pteronyssinus were detected at 97-98 kDa, 103-104 kDa and 134-139 kDa on both reducing and non-reducing blots. Major allergens at 84-85 kDa, 65-69 kDa and 44-45 kDa were only recognised on reducing blots, suggesting that these are fragments of the larger allergens. Only a few sera recognised group 1 or 2 allergens on blots of crude extracts or purified allergens. These results confirm that, in atopic dogs, high molecular weight allergens are the most important Dermatophagoides allergens, rather than the low molecular weight group 1 and 2 proteins.     

Serial thyroid hormone concentrations in healthy euthyroid dogs, dogs with hypothyroidism, and euthyroid dogs with atopic dermatitis.

Serum thyroxine (T4) and 3,5,3'-triiodothyronine (T3) concentrations were determined every 3 h for 12 h beginning at 8 a.m. in 20 healthy euthyroid dogs, 19 dogs with hypothyroidism, and 18 euthyroid dogs with atopic dermatitis. Status of thyroid function was based on history, physical findings, results of thyrotropin response testing, and requirement for thyroid hormone replacement therapy. Mean serum T4 and T3 concentrations did not vary significantly between blood samplings within each of the three groups of dogs. Between groups of dogs, mean serum T4 concentration was significantly (P less than 0.05) higher at each blood sampling time in healthy euthyroid dogs and euthyroid dogs with atopic dermatitis when compared to dogs with hypothyroidism. There was no significant difference in mean serum T4 concentration at any blood sampling time between healthy euthyroid dogs and euthyroid dogs with atopic dermatitis or in mean serum T3 concentrations at any blood sampling time between any of the three groups of dogs. Random fluctuation in serum T4 and T3 concentrations was found in dogs in all three groups. Random fluctuations were more common with serum T3 versus T4 concentrations. Consequently, sensitivity (0.88 versus 0.52), specificity (0.73 versus 0.45), predictive value for a positive test (0.75 versus 0.32), predictive value for a negative test (0.87 versus 0.65), and accuracy (0.80 versus 0.47) were better for serum T4 concentration than serum T3 concentration, respectively, when all blood samples were analysed. Measurement of serum T4 concentration was more accurate than serum T3 concentration in assessing the status of thyroid gland function.