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1.
OBJECTIVE: To determine the functionality of canine anti-Malassezia IgE via the passive transfer of immediate hypersensitivity localized to the skin (ie, cutaneous anaphylaxis) from atopic dogs with dermatitis attributable to overgrowth of Malassezia pachydermatis (Malassezia dermatitis [MD]) to healthy recipient dogs by use of the Prausnitz-Küstner (P-K) technique. ANIMALS: 7 clinically normal dogs, 32 atopic dogs with MD, serum from 11 atopic dogs with MD, and 3 healthy dogs without prior sensitization to M pachydermatis. PROCEDURE: Serum from atopic dogs with MD was used for P-K tests in 3 clinically normal recipient dogs. Serial dilutions of untreated, heat-inactivated, IgE-absorbed, and bovine serum albumin (BSA)-absorbed (control) aliquots of serum were injected ID in triplicate for dermal sensitization. Twenty-four, 48, and 72 hours later, a crude extract of M pachydermatis was injected ID into the sites used for sensitization injections, and immediate hypersensitivity reactions were graded on a 4-point scale. RESULTS: Untreated serum caused P-K reactivity beginning 24 hours after passive sensitization and persisting through 72 hours (titers, 1:32 to 1:64). Heat inactivation and IgE-absorption of serum eliminated P-K reactivity, whereas treatment of serum with BSA did not. CONCLUSIONS AND CLINICAL RELEVANCE: Analysis of P-K test results supports the passive transfer of cutaneous anaphylaxis by anti-Malassezia IgE and indicates it is functional in type-1 hypersensitivity reactions of atopic dogs with MD. Reduction or blockade of anti-Malassezia IgE in atopic dogs with MD may provide better clinical control of the disease.  相似文献   

2.
OBJECTIVE: To investigate the potential cell-mediated immune response of atopic dogs to the yeast Malassezia pachydermatis and to correlate it with the type-1 hypersensitivity (humoral) response of the same population of dogs. ANIMALS: 16 clinically normal dogs, 15 atopic dogs with Malassezia dermatitis, 5 atopic dogs with Malassezia otitis, and 7 atopic control (ie, without Malassezia dermatitis or otitis) dogs. PROCEDURE: A crude extract of M pachydermatis was extracted for use as an intradermal allergy testing reagent and for stimulation of isolated peripheral blood mononuclear cells in vitro. Flow cytometry was also used to assess cell surface antigenic determinants (CD3, CD4, CD8, CD14, CD21, CD45RA, surface immunoglobulin) on peripheral blood mononuclear cells. RESULTS: Atopic dogs with cytologic evidence of Malassezia dermatitis had an increased lymphocyte blastogenic response to crude M pachydermatis extract, compared with clinically normal dogs and dogs with Malassezia otitis. Atopic control dogs did not differ significantly in their responses from atopic dogs with Malassezia dermatitis or otitis. A significant correlation was not found between the lymphocyte blastogenic response and the type-1 hypersensitivity response to M pachydermatis within any of the groups. CONCLUSIONS AND CLINICAL RELEVANCE: Cell-mediated and humoral reactivities to M pachydermatis contribute to the pathogenesis of atopic dermatitis in dogs but are not directly correlated. Modification of the dysregulated immune response toward M pachydermatis may assist in the reduction of pathologic changes associated with an atopic dermatitis phenotype in dogs.  相似文献   

3.
Abstract We have previously shown that both atopic and normal dogs generate an IgG response to antigens of Malassezia pachydermatis . The aim of this study was to compare IgE responses to separated proteins of M. pachydermatis in 28 atopic dogs with Malassezia dermatitis and 22 clinically normal dogs using Western immunoblotting. Six different detection systems were evaluated in order to assess sensitivity and eliminate nonspecific binding and cross-reactivity. The protocol yielding the best results utilized a monoclonal mouse antidog IgE, an alkaline phosphatase conjugated goat antimouse IgG which had been passed through a canine IgG column 3 times, a chemiluminescent substrate and a digital imaging system. Proteins of 45, 52, 56 and 63 kDa were recognized by more than 50% of the atopic dog sera and thus represented major allergens. Only a minority of normal dogs showed faint IgE binding to these proteins. The results indicate that the majority of atopic dogs with Malassezia dermatitis have a greater IgE response than normal dogs, suggesting an IgE-mediated immune response may be clinically important in the pathogenesis of the disease.  相似文献   

4.
OBJECTIVE: To compare reactivities to intradermal injection of extracts of Dermatophagoides farinae, Dermatophagoides pteronyssinus, house dust mite mix, and house dust in dogs suspected to have atopic dermatitis. DESIGN: Retrospective study. ANIMALS: 115 dogs. PROCEDURES: Records of all dogs suspected to have atopic dermatitis that underwent intradermal testing between October 1996 and July 1998 were reviewed. Reactivities to intradermal injection of crude mixed house dust mite (1:25,000 wt/vol) and crude house dust (25 PNU/ml) extracts were compared with reactivities to intradermal injection of individual extracts of D farinae and D pteronyssinus (1:50,000 wt/vol). RESULTS: Ninety dogs were confirmed to have atopic dermatitis including 61 of the 69 dogs with positive reactions to either or both of the individual house dust mite extracts. Intradermal testing with the mixed house dust mite extract had sensitivity of 75%, specificity of 96%, and accuracy of 83%. Intradermal testing with the house dust extract had sensitivity of 30%, specificity of 93%, and accuracy of 56%. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that use of crude mixed house dust mite and crude house dust extracts for intradermal testing in dogs is not as accurate a method of determining house dust mite hypersensitivity as is the use of individual D farinae and D pteronyssinus extracts mainly because of the high percentage of false-negative results. Extracts of individual house dust mites are recommended for intradermal testing of dogs suspected to have atopic dermatitis.  相似文献   

5.
The purpose of this study was to evaluate reactions to intradermal injections of Tyrophagus putrescentiae extract in healthy dogs and dogs with atopic dermatitis and to compare the prevalence of positive reactions in the two groups. Twenty-one healthy dogs and 26 atopic dogs were tested intradermally with T. putrescentiae extract at 1000, 500, 250, 125, 63, 32 and 16 PNU/mL. Reactions were evaluated objectively and subjectively. A Mann-Whitney test was used to determine differences in grade of reaction to storage mites between healthy dogs and dogs with atopic dermatitis. Positive reactions to storage mite extract were most common at 1000 PNU/mL with approximately one third of normal and atopic dogs showing a positive reaction to T. putrescentiae. There was no significant difference in the incidence of positive reactions between normal and atopic dogs for any of the Tyrophagus extract concentrations.  相似文献   

6.
IgG immunoreactivity to Malassezia pachydermatis was compared in atopic and non-atopic dogs. Malassezia pachydermatis proteins with a molecular weight of 98 kDa were recognized at a significantly higher frequency in the sera of atopic dogs. Most of the atopic dogs with Malassezia dermatitis had a greater IgG response than did normal dogs.  相似文献   

7.
Twenty-eight atopic dogs, 22 pruritic, non-atopic dogs and 10 healthy dogs were ELISA tested. For calculations of diagnostic specificity and sensitivity, positive ELISA test results in non-atopic dogs were considered false positive results. The absence of any positive results in the atopic dogs was considered false negative results. The atopic dogs were tested both with ELISA and an intradermal test, utilising allergen extracts from the same manufacturer, to determine the frequency of positive allergen reactions in the ELISA test compared with the intradermal test. The Prausnitz-Küstner test was performed to evaluate the significance of a positive ELISA test result. Based on cross-tabulations with clinically defined atopic dermatitis, the ELISA test showed a sensitivity of 53.6% and a specificity of 84.4%. The correlation between the ELISA and the intradermal test was poor. Positive Prausnitz-Küstner tests were not obtained using sera from dogs that were intradermal test negative for the tested allergens, even though sera had high levels of IgE as measured by the ELISA. These findings question the significance of a positive ELISA test result and indicate that the test is not measuring functional allergen-specific IgE.  相似文献   

8.
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.  相似文献   

9.
Irritant threshold concentration (ITC) for intradermal testing (IDT) was determined in 31 healthy, clinically nonallergic dogs. Twenty‐three allergens were tested at five variable concentrations ranging from 1000 to 8000 PNU/mL. To distinguish irritant reactions from subclinical IgE‐mediated hypersensitivities, serum allergy testing was performed. ITCs were determined by evaluating the lowest concentration to which no dogs (0% cut‐off) and to which at least 10% of dogs (≥10% cut‐off) reacted. ITCs at the 0% cut‐off were: 1000 PNU/mL (Johnson grass), 2000 PNU/mL (Ash, Lamb’s Quarter and Bermuda), 3000 PNU/mL (Bahia, Rye, Pig Weed and Virginia Oak), 4000 PNU/mL (Marsh Elder and Maple), 5000 PNU/mL (Sorrel sheep) and 7000 PNU/mL (Cocklebur and Black Willow). ITC for Dog Fennel, Box Elder and Red Cedar was <1000 PNU/mL. ITCs at the ≥10% cut‐off were: 2500 PNU/mL (Johnson), 3000 PNU/mL (Box Elder), 5000 PNU/mL (Bahia), 6000 PNU/mL (Pigweed and Marsh Elder) and 8000 PNU/mL (Virginia Oak and Black Willow). For all other allergens, the ITC was >8000 PNU/mL and could not be determined. No significant agreement between positive values was found for the same allergen on IDT and serum allergy testing for each dog suggesting reactions caused by the determined ITCs are less likely subclinical IgE‐mediated reactions. These results suggest that ITCs may vary, also they may be very high for the allergens tested and that higher test concentrations may be used for IDT for the tested allergens without inducing an irritant reaction. Further studies are needed to evaluate the benefit of higher IDT concentrations in atopic dogs.  相似文献   

10.
Canine Malassezia dermatitis is frequently treated with systemic ketoconazole (KTZ) and itraconazole (ITZ). However, no information is available on the antifungal susceptibility to azoles and allilamine of Malassezia pachydermatis isolates from dogs with or without skin lesions. The present study was designed to evaluate the in vitro antifungal susceptibility of M. pachydermatis strains from dogs with or without skin lesions to KTZ, ITZ, miconazole (MICO), fluconazole (FLZ), posaconazole (POS), voriconazole (VOR) and terbinafine (TER) using the Clinical and Laboratory Standards Institute reference Broth Microdilution Method (CLSI M27-A2). The association between the susceptibility to antifungal compounds and the origin of M. pachydermatis, from skin with or without lesions has been also assessed. A total of 62 M. pachydermatis strains from healthy dogs (i.e., Group A=30) or with skin lesions (i.e., Group B=32) were tested. ITZ, KTZ and POS showed the highest activity against M. pachydermatis strains, whereas MICO TER and FLZ the lowest. A higher number of Malassezia resistant strains were registered among isolates from Group B than those from Group A. This study indicates that M. pachydermatis strains were susceptible to ITZ, KTZ, and POS. However, dogs with lesions may harbour strains with low susceptibility to antifungal agents and displaying cross-resistance phenomena to azole. The antifungal therapy in Malassezia infections requires careful appraisal of choice of drugs especially in cases of unresponsiveness to antifungal treatment or recurrent infections.  相似文献   

11.
Three dogs were examined because of episodes of recurrent pruritic dermatitis in the spring, the season of Japanese cedar (Cryptomeria japonica, CJ) pollination in Japan. The dogs were shown to be sensitive to CJ pollen allergen using intradermal testing and antigen-specific IgE measurement. Fluorometric enzyme-linked immunosorbant assay (ELISA) showed increased concentrations of IgE specific to Cry j 1 and a negative result for Cry j 2 in the three dogs. The concentrations of IgE specific to Cry j 1 during the season of CJ pollination were higher than the concentrations found during the off-season in all the dogs, and the variation in the concentrations correlated with the variation in clinical signs. Peripheral blood mononuclear cells showed apparent proliferative responses to crude CJ pollen antigen and Cry j 1 during CJ pollination season. These findings indicated that Cry j 1 was the major allergen recognized by IgE and lymphocytes and resulted in the development of type I hypersensitivity to CJ pollen allergen in these atopic dogs.  相似文献   

12.
To investigate the role of Malassezia pachydermatis as a pathogenic agent in canine otitis, a comparative analysis of isolates from normal and diseased external ear canals in dogs was undertaken. Specimens were collected from the ears of dogs with unilateral or bilateral otitis and from healthy dogs. Mycological analysis was by direct microscopy and fungal culture on Sabouraud's dextrose agar and Dixon's agar. Of the otitis specimens, 63.7% showed typical Malassezia cells on cytological examination. In samples taken from the healthy ears of dogs with unilateral otitis, only 21.43% (P<0.05) showed evidence of Malassezia. M. pachydermatis was identified cytologically and culturally in 57.53% (P<0.05), 14.29% and 30.0% of samples from the ears of dogs with otitis, from the healthy ears of dogs with unilateral otitis and from the ears of healthy dogs with no otitis. In the group with otitis associated with M. pachydermatis, the poodle was the most common breed (39.29%; P<0.05), whereas in the group without otitis, the German Shepherd breed was prominent (although this observation was not statistically significant). In both groups, the majority of dogs with M. pachydermatis were aged between 1 and 3 years (P<0.05). The higher incidence of M. pachydermatis isolated from the ears of dogs with otitis externa suggests a putative pathogenic role of this yeast in this condition.  相似文献   

13.
Abstract Epidermal hyperplasia is one of the major histopathological features seen in dogs with Malassezia dermatitis. The aim of this study was to investigate the effects of extracts and culture supernatants from Malassezia pachydermatis on the proliferation of canine keratinocytes. Keratinocyte cultures were established from normal dog skin, and cell monolayers were co-cultured with Malassezia extracts (prepared either with or without protease inhibitors) and supernatants derived from organisms grown in liquid culture. The proliferation of keratinocytes was measured using a colourimetric assay. Neither the culture supernatants nor the Malassezia extracts had significant effects on the proliferation rate of canine keratinocytes, regardless of whether protease inhibitors were present or not. The results indicate that the epidermal hyperplasia seen in Malassezia dermatitis is unlikely to be caused directly by secretion of products from the organism.  相似文献   

14.
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.  相似文献   

15.
OBJECTIVE: To compare a radioallergosorbent test and 2 ELISA with intradermal testing for the determination of environmental allergen hypersensitivity in horses with and without atopic diseases. DESIGN: Prospective clinical study. ANIMALS: 10 horses with recurrent urticaria, 7 with atopic dermatitis, 16 with chronic obstructive pulmonary disease, and 22 without atopy. PROCEDURE: History, physical examination, hemogram, serum biochemical analyses, bronchoalveolar lavage, and an intradermal test (used as the criterion standard) with a regional panel of 73 allergens were performed in all horses. Serum was analyzed by use of the 3 in vitro assays of allergen-specific IgE. RESULTS: An ELISA based on the alpha chain of the high-affinity IgE receptor, the Fcepsilon receptor immunoglobin epsilon chain (FcepsilonRIalpha) for IgE, had the overall highest kappa statistic (0.238), positive predictive value (49%), and negative predictive value (78%). Overall agreement between the FcepsilonRIalpha-based ELISA and the intradermal test was fair. The highest kappa statistic was obtained by the FcepsilonRIalpha-based ELISA in horses with atopic dermatitis (0.330). Kappa statistics for the radioallergosorbent test and a polyclonal antibody-based ELISA agreed slightly with that of the intradermal test at best. CONCLUSIONS AND CLINICAL RELEVANCE: None of the 3 serum allergy tests reliably detected allergen hypersensitivity, compared with the intradermal test. The FcepsilonRIalpha-based ELISA performed significantly better overall than the other 2 tests. Low sensitivity of all 3 assays indicates the need for continued study to elucidate a more sensitive test for the determination of potentially pathogenic allergens in horses.  相似文献   

16.
A series of 18 allergic cats with multifocal Malassezia spp. overgrowth is reported: atopic dermatitis was diagnosed in 16, an adverse food reaction in another and one was euthanized 2 months after diagnosis of Malassezia overgrowth. All the cats were otherwise healthy and those tested (16 out of 18) for feline leukaemia or feline immunodeficiency virus infections were all negative. At dermatological examination, multifocal alopecia, erythema, crusting and greasy adherent brownish scales were variably distributed on all cats. Cytological examination revealed Malassezia spp. overgrowth with/without bacterial infection in facial skin (n = 11), ventral neck (n = 6), abdomen (n = 6), ear canal (n = 4), chin (n = 2), ear pinnae (n = 2), interdigital (n = 1) and claw folds skin (n = 1). Moreover, in two cats Malassezia pachydermatis was isolated in fungal cultures from lesional skin. Azoles therapy alone was prescribed in seven, azoles and antibacterial therapy in eight and azoles with both antibacterial and anti-inflammatory therapy in three of the cats. After 3-4 weeks of treatment, substantial reduction of pruritus and skin lesions was observed in all 11 cats treated with a combined therapy and in five of seven treated solely with azoles. Malassezia spp. overgrowth may represent a secondary cutaneous problem in allergic cats particularly in those presented for dermatological examination displaying greasy adherent brownish scales. The favourable response to treatment with antifungal treatments alone suggests that, as in dogs, Malassezia spp. may be partly responsible for both pruritus and cutaneous lesions in allergic cats.  相似文献   

17.
Isolates of Malassezia pachydermatis from healthy dog skin and from dogs with atopic dermatitis were molecularly characterized using internal spacer 1 (IGS1) region analyses, and their phospholipase A2 activity and pH growth profiles were then characterized in vitro. The percentage of isolates from healthy dogs that had the following IGS1 subtypes (isotype, %) were as follows: 1A, 6%; 1B, 27%; 1C, 11%; 2A, 6%; 2B, 6%; 3A, 11%; 3C, 3%; and 3D, 24%. In contrast, 9% of isolates from dogs with atopic dermatitis were isotype IB and 91% were isotype 3D, indicating that isolates of subtype 3D were the most prevalent in dogs with atopic dermatitis. Production of phospholipase A2 was statistically higher in isolates of subtype 3D than in the other subtypes. The subtype 3D isolates showed enhanced growth on alkaline medium compared with non-3D subtype isolates. The main clinical sign of canine Malassezia dermatitis is waxy exudates on the skin, which predispose the patient to development of a yeast overgrowth of the subtype 3D. Increased phospholipase A2 production may be involved in the inflammatory process associated with Malassezia dermatitis.  相似文献   

18.
Aim of the present study was to determine the distribution and quantification of Malassezia yeasts on a wide number of cutaneous sites in atopic dogs by means of a semiquantitative swab technique. A possible relationship between the presence of clinical signs and the occurrence and population size of yeasts was attempted. Forty-one privately owned atopic dogs of different age and breed were sampled. Results were expressed as colony forming units per swab. Malassezia colonies obtained from each plate were counted, scored and typed. All dogs yielded Malassezia pachydermatis from at least one skin area. Yeast population mean size by site was 6.98 (S.D.=3.47) as compared to other body areas. The frequence of isolation was higher from interdigital areas (70.7%), ears (63.4%), nail folds (35.7%), mouth (33.3%), groin (30.9%), conjunctiva and axillae (23.8%), perineum and anus (19%), perianal glands (9.5%). Ears, anus, interdigital areas, perianal glands and groin yielded the largest mycotic amount. M. pachydermatis was the sole species of yeast to colonize canine skin in examined animals. No statistical correlation between the presence of cutaneous alterations and Malassezia isolation was detected. Highest scores were not exclusively found on affected areas, but also on lesion-free sites, demonstrating that atopic animals can be heavily colonized also in apparently healthy areas.  相似文献   

19.
OBJECTIVE: To investigate the direct interaction between canine keratinocytes and live Malassezia pachydermatis and thereby determine the role of these organisms in the pathogenesis of epidermal hyperplasia associated with Malassezia dermatitis in dogs. SAMPLE POPULATION: Primary canine keratinocyte cultures established from skin samples obtained from clinically normal dogs. PROCEDURE: The proliferative response of keratinocytes co-cultured with Malassezia organisms for 1, 2, or 3 days was assessed by use of direct manual counting (to determine the number of keratinocytes in both the monolayer and the medium) and immunohistochemical staining techniques involving antibodies against proliferating cell nuclear antigen (PCNA) and another cellular proliferation marker, Ki-67. The potential cytotoxic effect of Malassezia organisms was investigated by use of an apoptosis detection kit to label keratinocytes co-cultured with M. pachydermatis that underwent apoptosis. RESULTS: No stimulatory effect of Malassezia organisms on canine keratinocyte proliferation was detected via cell counting and immunohistochemical techniques. However, there was a significant increase in dead keratinocytes in the medium with increasing numbers of Malassezia organisms in the co-culture. More apoptotic cells were observed in keratinocyte monolayers co-cultured with high numbers of M. pachydermatis than there were in monolayers cultured without Malassezia organisms, and the number increased after prolonged incubation. CONCLUSIONS AND CLINICAL RELEVANCE: M. pachydermatis did not stimulate canine keratinocyte proliferation in vitro. The results suggested that the epidermal hyperplasia observed in dogs with Malassezia dermatitis is unlikely to be caused by a direct effect of the organism on the keratinocyte cell cycle, but is likely to involve other mechanisms.  相似文献   

20.
The incidence of dermatitis and otitis resulting from overgrowth of M. pachydermatis is great enough that cytological sampling techniques should be considered a routine part of the dermatological examination. Because most cases of MD and Malassezia otitis cannot be grossly distinguished from bacterial pyoderma and otitis, respectively, efficiency in performing cytology testing of skin and ear canal exudate is essential to the successful diagnosis and management of pruritic skin diseases and otitis. Although Malassezia infections are rarely primary, therapy can be instituted to remove the yeast as a confounding factor while a differential diagnosis is pursued in evaluating the underlying disease process.  相似文献   

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