IgE and IgG antibodies to flea antigen in differing dog populations

Cellular and Humoral Responses to Cte f 2, a Cat Flea Allergen, in Children with Papular Urticaria

BACKGROUND

Papular urticaria (PU) is a common insect bite skin hypersensitivity in tropical countries. In order to gain insight into its causal allergens, we aimed to evaluate cellular and humoral immune responses to the recombinant salivary antigen Cte f 2 from the cat flea Ctenocephalides felis.

METHOD

Sixty patients with PU and 27 healthy controls were included in this study. Specific IgE, IgG, IgG1, and IgG4 against Cte f 2 and C. felis extract were determined by ELISA. The T-cell response was analyzed using a carboxyfluorescein succinimidyl ester (CFSE)-based dilution assay and Th1/Th2/Th17 cytokine measurements. In addition, a proteomic analysis of IgG and IgE reactive spots of C. felis extract was performed.

RESULTS

The frequency of IgE sensitization to Cte f 2 was similar between patients (36.7%) and controls (40.7%). The specific IgE, IgG1, and IgG4 responses to Cte f 2 and C. felis extract were not significantly different between patients and controls. Among the 3 conditions (i.e., Cte f 2, C. felis extract, and only medium) Cte f 2 was the strongest inducer of CD3+CD4+ proliferation in the patients; however, the mean response was not significantly different from those in controls (Cte f 2: 4.5 vs. 2.5%; p = 0.46). No salivary proteins were identified in C. felis, and most of the spots were identified as muscle-skeletal components (tropomyosin, actin, myosin, and ankirin).

CONCLUSIONS

Cte f 2 induces IgE and IgG production as well as T-cell proliferation in children living in a geographical area where PU induced by a flea bite is common. The use of C. felis extract is not recommended for the study of bite-induced hypersensitivity disease since salivary antigens are not well represented.

Evaluation of the murine immune response to Xenopsylla cheopis flea saliva and its effect on transmission of Yersinia pestis

Background/Aims

Arthropod-borne pathogens are transmitted into a unique intradermal microenvironment that includes the saliva of their vectors. Immunomodulatory factors in the saliva can enhance infectivity; however, in some cases the immune response that develops to saliva from prior uninfected bites can inhibit infectivity. Most rodent reservoirs of Yersinia pestis experience fleabites regularly, but the effect this has on the dynamics of flea-borne transmission of plague has never been investigated. We examined the innate and acquired immune response of mice to bites of Xenopsylla cheopis and its effects on Y. pestis transmission and disease progression in both naïve mice and mice chronically exposed to flea bites.

Methods/Principal Findings

The immune response of C57BL/6 mice to uninfected flea bites was characterized by flow cytometry, histology, and antibody detection methods. In naïve mice, flea bites induced mild inflammation with limited recruitment of neutrophils and macrophages to the bite site. Infectivity and host response in naïve mice exposed to flea bites followed immediately by intradermal injection of Y. pestis did not differ from that of mice infected with Y. pestis without prior flea feeding. With prolonged exposure, an IgG1 antibody response primarily directed to the predominant component of flea saliva, a family of 36–45 kDa phosphatase-like proteins, occurred in both laboratory mice and wild rats naturally exposed to X. cheopis, but a hypersensitivity response never developed. The incidence and progression of terminal plague following challenge by infective blocked fleas were equivalent in naïve mice and mice sensitized to flea saliva by repeated exposure to flea bites over a 10-week period.

Conclusions

Unlike what is observed with many other blood-feeding arthropods, the murine immune response to X. cheopis saliva is mild and continued exposure to flea bites leads more to tolerance than to hypersensitivity. The immune response to flea saliva had no detectable effect on Y. pestis transmission or plague pathogenesis in mice.

The saliva of blood-feeding arthropods contains a variety of components that prevent blood clotting and interfere with the immune system of the vertebrate host. These properties have been shown to enhance or inhibit the transmission of different pathogens transmitted by arthropods. Yersinia pestis, the bacterial agent of plague, is maintained in nature by flea to rodent transmission cycles. Most rodents live in close association with fleas and are constantly being bitten by them, but the influence this has on plague transmission is unknown - previous studies used laboratory animals which have never experienced a flea bite. We found that flea bites caused a mild inflammatory response in mice, and eventually an antibody response to components of flea saliva, but did not significantly affect pathogenesis. The transmission of Y. pestis by infected fleas and the incidence rate of bubonic plague mortality were the same in mice that had been exposed to frequent uninfected flea bites and mice with no prior exposure to fleas. Therefore, in contrast to what has been shown for many other arthropod-borne disease systems, vector saliva did not enhance or inhibit Y. pestis infection in mice, regardless of the immune status of the host to flea saliva.

Measurement for canine IgE using canine recombinant high affinity IgE receptor α chain (FcεRIα)

To detect allergen-specific IgE in dogs with allergic diseases, we developed a recombinant canine high affinity IgE receptor α chain (FcεRIα)-based IgE detection system. Using the recombinant protein of canine FcεRIα expressed by an Escherichia coli expression system, we could detect house dust mite (Dermatophagoides farinae) allergen-specific IgE in sera from dogs naturally and experimentally sensitized to this allergen with ELISA and western blotting. The IgE binding activity of recombinant canine FcεRIα on ELISA was impaired by heat treatment of these sera. The specificity of this recombinant canine FcεRIα-based IgE detection system was confirmed by inhibition assays with canine IgE. The recombinant canine FcεRIα-based IgE detection system established in this study offers an alternative tool to measure allergen-specific IgE in dogs.

Specific pattern of flea antigen recognition by IgG subclass and IgE during the progression of papular urticaria caused by flea bite

BACKGROUND

Papular urticaria caused by flea bite presents clinical symptoms of a hypersensitivity reaction accompanied by skin lesions. However, the pattern of recognition by different antibody isotypes during the progression of the disease is unknown. This study evaluated variations in immunoglobulin E and immunoglobulin G subclass antibody responses to flea antigens during the progression of papular urticaria caused by flea bite

METHODS

Twenty-five patients clinically diagnosed with papular urticaria due to flea bite were included. Ten healthy children were included as controls. Recognition of antigens from complete flea body extract by patients and healthy controls was determined using immunoblot assays.

RESULTS

The results revealed that patients with 2-5 years of papular urticaria evidenced more IgE bands than those with shorter or longer durations of symptoms. In contrast, healthy children showed a predominance of immunoglobulin G1 and immunoglobulin G3. The majority of the recognised antigens were low molecular weight proteins (<90 kDa). Proteins with molecular weights between 16-20, 21-25, and 31-35 kDa showed different patterns of recognition between patients and healthy children.

CONCLUSION

The predominant specific antibody isotypes vary according to the time elapsed since the onset of symptoms in papular urticaria caused by flea bite.

Induction of adaptive T regulatory cells that suppress the allergic response by coimmunization of DNA and protein vaccines

Allergen-induced immediate hypersensitivity (AIH) is a health issue of significant concern. This robust inflammatory reaction is initiated by the allergen-specific T cell responsiveness. Severe lesion reactions on skin are consequential problem requiring medical treatment. Effective Ag-specific treatments or preventions are lacking. Using a rodent model of AIH induced by flea allergens, we first report that coimmunization of DNA and protein vaccines encoding the flea salivary specific Ag-1 ameliorated experimental AIH, including Ag-induced wheal formation, elevated T cell proliferation, and infiltration of lymphocytes and mast cells to the site of allergen challenge. The amelioration of AIH was directly related to the induction of a specific population of flea antigenic specific T cells exhibiting a CD4(+)CD25(-)FoxP3(+) phenotype, a characteristic of regulatory T (T(REG)) cells. These T(REG) cells expressing IL-10, IFN-gamma, and the transcriptional factor T-bet after Ag stimulation were driven by a tolerogenic MHC class II(+)/CD40(low) dendritic cell population that was induced by the coimmunization of DNA and protein vaccines. The tolerogenic dendritic cell could educate the naive T cells into CD4(+)CD25(-)FoxP3(+) T(REG) cells both in vitro and in vivo. The study identified phenomenon to induce an Ag-specific tolerance via a defined Ag vaccinations and lead to the control of AIH. Exploitation of these cellular regulators and understanding their induction provides a basis for the possible development of novel therapies against allergic and related disorders in humans and animals.

Diagnosis of flea allergy dermatitis: comparison of intradermal testing with flea allergens and a FceRI alpha-based IgE assay in response to flea control

The objective of this study was to evaluate the accuracy of in vivo and in vitro tests in the diagnosis of flea allergy dermatitis in comparison with history, clinical signs and response to flea control. Intradermal testing using four different sources of flea allergens and FcepsilonRIalpha-based immunoglobulin (Ig)E assays were performed in 15 flea-allergic dogs, 15 atopic dogs and 15 dogs infested with fleas but showing no clinical signs of skin disease. Sensitivity, specificity, negative predictive value, positive predictive value and accuracy were calculated for all five tests and results varied greatly. Sensitivity, specificity and overall accuracy were 27, 83 and 64%, respectively, for one extract (Isotec), 67, 90 and 82% for another extract (Greer), 93, 90 and 91% for flea saliva, 40, 90 and 73% for the recombinant Cte f 1 both produced by Heska Corp. and 87, 53 and 64% for a FcepsilonRIalpha-based IgE assay. These results indicate that intradermal testing with flea extracts is more accurate in the diagnosis of flea allergy dermatitis than in vitro tests. Moreover, pure flea saliva used as a reagent for intradermal testing provided the best results in terms of sensitivity, specificity and overall accuracy although the Greer extract, a whole body flea extract, also allowed a good correlation between intradermal testing results and clinical approach to flea allergy dermatitis diagnosis.

The immunopathogenesis of flea allergy dermatitis in dogs, an experimental study

In this study, we investigated the development of clinical disease and immune responses in the development of an experimental model of flea allergy dermatitis. Dogs were randomly divided into four treatment groups and were infested with fleas on two different feeding schedules (continuous and episodic). Group 1 consisted of four non-exposed dogs (negative controls) and Group 2 consisted of six dogs exposed to fleas continually. Groups 3 and 4 consisted of 14 dogs each that were exposed to fleas on an episodic schedule (two consecutive days every other week for 12 weeks). Group 4 also received intraperitoneal injections of a low dose of lectin (ricin) with immunomodulatory properties. The purpose of Group 4 was to investigate the effects of ricin on enhancing the development of clinical signs, flea antigen-specific IgE levels and altering the number of CD4+ and CD8+ T cell subsets in peripheral blood. Clinical signs developed in all flea exposed dogs, however, the dermatology lesion scores were less and shorter in duration for continuously exposed dogs compared to episodic exposed dogs, independent of ricin treatment. Lesion development was concentrated in the flea triangle and consisted principally of erythema, followed by alopecia, excoriation, papules, and crusts. CD4+ and CD8+ lymphocyte subsets or IgE levels were not altered by ricin treatment. Flea antigen-specific IgE values were highest in dogs exposed to fleas on a continuous basis compared to those episodically exposed. A greater percentage of clinical responder dogs with negative flea-specific IgE titers or negative intradermal test (IDT) were present in the episodic exposure groups than in the continuous exposure group. IgE titers corresponded slightly better with clinical responders than the IDT. The agreement between the IgE titers and IDT was good (weighted K = 0.67). Histopathology of skin samples were consistent with a Type I hypersensitivity. In conclusion, we were able to develop a model of flea allergy dermatitis by experimentally exposing dogs to fleas on an episodic and continuous feeding schedule. In this study, continuously exposed dogs did not develop immunotolerance, and ricin did not enhance the development of FAD.

Examination of serum total IgG1 concentration in atopic and non-atopic dogs

In this study, serum immunoglobulin G1 (IgG1) concentrations were examined in atopic and non-atopic dogs receiving different levels of parasite control. Significantly lower serum total IgG1 concentrations were found in non-atopic dogs receiving stringent parasite control than in atopic dogs or non-atopic dogs receiving less stringent parasite control. Examination of serum total IgG1 concentrations of atopic dogs after six months of allergen specific immunotherapy (ASIT) showed a significant increase in serum total IgG1 concentrations. It is proposed that serum total IgG1 concentrations are affected by parasitism, atopic dermatitis and ASIT.

Pilot study to assess the effects of early flea exposure on the development of flea hypersensitivity in cats

This pilot study was to determine if early oral flea exposure reduces the incidence of flea allergy dermatitis (FAD) in cats. Eighteen kittens, assigned to three groups, received no flea exposure, oral flea exposure or flea infestation for 12 weeks. Then all the kittens were exposed continually to fleas for 31 weeks. Sensitization was monitored using intradermal testing (IDT), in vitro measurement of anti-flea saliva immunoglobulin E (IgE) and development of FAD. There was no statistically significant difference between groups in IDT reactions, in vitro data or clinical scores. The development of FAD was not associated with the presence of anti-flea saliva IgE. However, the development of a delayed reaction to flea bite was associated with symptoms after flea exposure. Although not statistically significant, the FAD scores in the oral group were lower than in the controls. Further studies are required to determine the role of oral flea exposure in the development of FAD in cats.

Flea bite hypersensitivity: new aspects on the involvement of mast cells

A study was performed to test the effect of sensitization to flea antigen, followed by exposure to fleas on mast cells (MCs), their subtypes, and IgE+ cells. Biopsies were taken from flea-sensitized dogs (n=28) and non-sensitized dogs (n=5) that had been exposed to fleas. Control groups consisted of flea-sensitized (n=12) and non-sensitized dogs (n=9) that were not exposed to fleas. Biopsies, taken before, 24 and 72 h after local flea exposure, were stained with haematoxylin and eosin (H&E), toluidine blue, a double labelling technique for MC chymase and tryptase and anti-IgE. An intradermal test for flea antigen was performed and serum titres of allergen-specific IgE and IgG were measured. Significantly higher numbers (P<0.001) of double labelled MCs compared to toluidine blue stained MCs were detectable in flea-sensitized dogs independent of flea exposure. In contrast, in non-sensitized dogs, the number of toluidine blue stained MCs and the number of double labelled MCs did not differ. In flea-sensitized dogs after flea exposure the percentage of C-MC was significantly increased at day 1 (P<0.001) and day 3 (P<0.001), whereas the percentage of TC-MCs decreased significantly at day 1 (P<0.001) and day 3 (P<0.05). The percentage of T-MCs decreased (P<0.05 day 0 versus day 1; P<0.05 day 0 versus day 3). No significant difference was detectable after toluidine blue staining and staining for IgE+ cells between the groups nor between the MC density and the number of IgE+ cells. All flea-sensitized dogs had positive skin tests to flea antigen and high serum titres of flea-specific serum IgE and IgG antibodies. In non-sensitized dogs, these results were negative. Our data provide strong evidence for an upregulation of MC proteases during the process of sensitization and a generalized selective release of mast cell tryptase after exposure to the antigen.

Canine atopic dermatitis: a retrospective study of 266 cases examined at the University of California, Davis, 1992-1998. Part I. Clinical features and allergy testing results

The medical records of 266 dogs diagnosed as having atopic dermatitis were reviewed. Statistical data were evaluated referable to breed predilections, clinical signs and positive reactions to allergens. Positive reactions were most common to house dust mites (more common with clinical signs in the fall) followed by moulds (more common with clinical signs in the fall and spring). Dogs with positive reactions to moulds, trees or cultivated plants were more likely to have skin and ear yeast infections. Dogs with positive reactions to cultivated plants were more likely to have otitis externa and pedal lesions. Positive reactions to house dust were more common in dogs with early onset of signs and in those tested early in the disease. Dogs had more positive reactions to weeds when allergy tests were performed in the summer and fall. Positive reactions to flea antigen were highly correlated with the clinical diagnosis of flea allergy dermatitis.

The ACVD task force on canine atopic dermatitis (XI): the relationship between arthropod hypersensitivity and atopic dermatitis in the dog

The relationship between arthropod allergen hypersensitivity and the development of canine atopic dermatitis (AD) is unclear. It has been shown that dogs with AD are more likely to exhibit positive intradermal reactivity to flea allergens than non-pruritic dogs from the same flea-endemic geographic region. Also, dogs in a flea endemic region are four times more likely to suffer from flea allergy dermatitis (FAD) and AD than from FAD alone. These results provide indirect evidence to support the hypothesis that, in the canine species, atopy predisposes to the development of hypersensitivity to flea allergens and eventually to FAD. A causal relationship between insects other than fleas and canine AD has not been identified with certainty.

Induction of feline flea allergy dermatitis and the incidence and histopathological characteristics of concurrent indolent lip ulcers

The objectives of this study were to characterize the role of intermittent vs. continual flea exposure in the development of flea allergy dermatitis (FAD) in cats, assess the accuracy of intradermal skin testing (IDST) and in vitro testing, and document the incidence and histopathological features of indolent lip ulcers. Ten flea-naive cats were divided into two groups. One group received intermittent flea exposure for 120 days. Thereafter, both groups of cats received continuous flea exposure for 120 days. In vitro testing for flea salivary antibody and IDST utilizing both whole flea antigen and flea salivary antigen were performed. Eight of 10 cats developed clinical signs of FAD within 3 months and five of these eight cats developed lip ulcers which where characterized histopathologically by ulceration with predominantly neutrophilic inflammation and surface bacterial colonization. There was no association between the presence or absence of clinical signs and positive IDST or in vitro results, and no difference in the development of clinical signs was noted between the two groups of cats.

Insect and arachnid hypersensitivity

Insect hypersensitivity reactions can have a large number of clinical presentations. The majority of reactions are pruritic and involve the short- or sparsely haired areas of the body. Most are associated with eosinophilic infiltration into the skin, often in a perivascular pattern. The diagnosis may be based on compatible clinical signs and improvement with aggressive insect control and, in some cases, confirmation via provocative exposure. Intradermal, prick, or serum testing for allergen-specific IgE can be used to document the presence of reaginic antibodies against insect allergens. Treatments include avoidance, aggressive insect control, and symptomatic support; in some cases, immunotherapy may be useful in decreasing the severity of clinical reactions to insects.

Allergen-specific IgE and IgGd antibodies in atopic and normal dogs

Intradermal skin tests (IDSTs) were performed on 65 atopic and 24 normal dogs. The levels of allergen-specific IgE and IgGd antibodies were determined in serum samples by enzyme-linked immunosorbent assay (ELISA) using the same 12 allergens that were used in the IDST on normal dogs. The correlation between the levels of IgE and IgGd to Dermatophagoides farinae (DF) and Dermatophagoides pteronyssinus (DP) was examined. The sensitivity, specificity and positive and negative predictive values of allergen-specific IgE and IgGd levels in the total dog population were also compared. Results were consistent and reproducible for 9/12 allergens, but in the case of house dust, flea and Alternaria tenuis, a less discriminating standard curve and the fact that the negative control gave positive results, suggests non-specific binding and that these allergens are complex and should not be employed without further purification. A high percentage of atopic dogs had positive IDSTs and detectable IgE and IgGd antibodies to DF, DP and house dust. Similar results were obtained in the normal dog population. There were significant correlations between allergen-specific IgE and IgGd levels to DF and DP. However, in contrast to IgE, allergen-specific IgGd in normal dogs was higher than in atopic dogs. Furthermore, a high percentage of the atopic population had detectable IgGd to unrelated allergens, despite negative IDSTs. Overall, the negative predictive values were similar for both IgE and IgGd. Sensitivities were higher in the allergen-specific IgGd assays, but the specificities and positive predictive values were higher in the allergen-specific IgE assays. In conclusion, the concordance of IDSTs with ELISA results to DF and DP in normal dogs without clinical signs implied the possible heterogeneity of IgE in dogs. The presence of IgGd directed against apparently irrelevant allergens in atopic patients and the high levels of IgGd in normal dogs to the most common allergens, DF and DP, implied an uncertain role of IgGd in canine atopic disease. Therefore, the detection of allergen-specific IgE is a more useful adjunct to the diagnosis of atopic disease in the dog than IgGd.

Characterization of two dog IgE-specific antibodies elicited by different recombinant fragments of the epsilon chain in hens

Two recombinant [His]6-tagged fragments of the canine immunoglobulin E (IgE) heavy chain (second domain: IgEf2 and third and fourth domains: IgEf3/4) were cloned, expressed in Escherichia coli (E. coli) as [His]6-tagged proteins, and affinity-purified over nickel-nitrilotriacetic acid columns. The recombinant proteins were used to immunize hens. The raised and affinity-purified chicken antibodies (Ab) isolated from egg yolk exhibited specific binding to the respective recombinant canine IgE fragment (IgEf) on immunoblots and displayed high titers against the IgEf in ELISA. Immunoblotting of canine serum separated by PAGE under native conditions with the IgEf2- and IgEf3/4-specific Ab resulted in staining of a protein of approximately 180 kilodaltons (kD). The IgEf3/4-specific Ab further recognized an 80 kD protein in IgEf3/4-specific Ab affinity-enriched dog serum separated under denaturing conditions. In an ELISA for the detection of antigen-specific IgE in dog serum, reduced binding of the IgEf-specific Ab was observed after heat treatment of the dog serum. The reactivity of both of the raised chicken Ab was only present in postimmune reagents and could only be inhibited by preincubation with the IgEf used for immunization and not with dog immunoglobulin G, E. coli extract, or with a nonrelevant recombinant [His]6-tagged protein. In immunohistochemistry, the IgEf3/4-specific Ab specifically recognized cells in paraffin-embedded tissue sections of lymph nodes. Furthermore, both of the IgEf-specific Ab elicited positive immediate type 1 skin reactions in dogs. Semiquantitative assessment of total serum IgE in dogs was developed using IgEf2-specific Ab as coating reagent and the biotinylated IgEf3/4-specific Ab as developing Ab in ELISA. In conclusion, both IgEf-specific Ab recognize native dog IgE with the advantages that they are directed against different and known constant domains of the IgE molecule, and that they can be used for immunohistochemistry on paraffin-embedded tissue. The two dog IgE-specific Ab could initiate clinical research on the involvement of immediate-type hypersensitivity reactions in dogs.

Canine leucocyte histamine release: response to antigen and to anti-IgE

Histamine release from canine leucocyte-enriched peripheral blood preparations was measured in atopic, non-atopic and artificially sensitised dogs after immunological challenge with D. farinae antigen and anti-IgE. Total cell histamine and spontaneous histamine release was also measured. The total cell histamine content of equal leucocyte preparations was not statistically significant between the atopic and non-atopic groups. At all dilutions of antigen a higher amount of histamine was released from the leucocytes of atopic dogs than was seen in the non-atopic group. No histamine release in response to D. farinae was seen in the sensitised dogs although a statistically significant increase in serum D. farinae-specific IgE could be demonstrated after sensitisation (P < 0.03). Histamine release in response to anti-IgE was significantly greater in the atopic dogs than the non-atopic dogs (P < 0.004) and the sensitised dogs (P < 0.003). There was no statistically significant difference in total serum IgE between the groups. The authors conclude that the leucocytes of atopic dogs have a greater tendency to release histamine than those of normal and artificially sensitised dogs and that this is independent of the concentration of total serum IgE or antigen-specific IgE. They suggest that there may be immunoregulatory abnormalities in atopic dogs intrinsic to the atopic state as is described in man.

Concentrations of total serum IgE, IgA, and IgG in atopic and parasitized dogs

Concentrations of total serum IgE, IgA, and IgG were measured in 36 atopic and 16 parasitized dogs, and compared them with 30 healthy control dogs. IgE was measured using enzyme-linked immunosorbent assay. IgA and IgG were measured using radial immunodiffusion assays. Mean total serum immunoglobulin (Ig) E concentrations in healthy, atopic and parasitized dogs were 7.1 units (U) ml-1, 5.8 U ml-1 and 14.3 U ml-1, respectively. Mean total serum IgA concentrations in the same groups were 103.3 mg dl-1, 63.2 mg dl-1 and 67.3 mg dl-1, respectively. Mean total serum IgG concentrations were 1066 mg dl-1, 1621 mg dl-1 and 1480 mg dl-1 in the three groups. There was no significant difference in IgE concentrations between these groups of dogs. IgA levels were significantly lower in atopic and parasitized dogs compared with healthy dogs (P < or = 0.05), whereas IgG levels were significantly higher in the atopic and parasitized dogs (P < or = 0.005). These results suggest that measurement of total serum IgE would be of no benefit in the preliminary clinical investigation of a suspected atopic dog. The lower IgA and higher IgG concentrations in both atopic and parasitized dogs suggest that similar regulatory mechanisms governing immunoglobulin synthesis occur in canine allergic and parasitic disease, promoting IgG synthesis but down-regulating IgA production.

IgG and IgE antibodies against antigens of the cat flea, Ctenocephalides felis felis, in sera of allergic and non-allergic dogs

Antigens from a soluble extract of cat fleas (FS) were separated using SDS-PAGE, and transferred to nitrocellulose paper. Sera from dogs shown by use of a provocative flea feeding test to be either allergic (23 dogs) or non-allergic (20 dogs) to flea bites, were used in Western blots to identify flea antigens that react with canine IgG or IgE. The sera were also tested in ELISA against FS to quantify levels of IgG and IgE antibodies. Antibodies present in the sera of both flea allergic and non-allergic dogs identified multiple antigens. There was a great diversity of responses within each group, and there was no pattern of reactivity that distinguished dogs with flea allergy from dogs not allergic to fleas. IgG and IgE antibodies were not significantly different between the two groups of dogs. These results demonstrated that there is little association between particular antibody responses and allergic reactivity of dogs to fleas.

The cat flea: biology, ecology and control

Control failures and recurrences of infestation of dogs, cats and their home environment with the cat flea, Ctenocephalides felis felis are common. Attempts to control these infestations are often impaired by an inadequate understanding of the interaction of the cat flea with its hosts and environment. This review presents information on the medical and veterinary importance of the cat flea and discusses recent information on the environmental and host factors that affect its development and survival. Additionally, information is presented on the use and effectiveness of various insecticides and insect growth regulators against the four life stages.

Flea allergy dermatitis

Flea allergy dermatitis is one of the most common causes of pruritus in dogs and cats. The degree of pruritus observed in the allergic animal varies widely and is dependent on numerous factors. Management of the flea-allergic patient is extremely frustrating for the owner and the veterinarian. Establishing an organized flea control program for use on the patient and in the environment will help to avoid frustration when dealing with this common ectoparasite of cats and dogs.

Aspects of the immunopathogenesis of flea allergy dermatitis in dogs

This paper reviews the current data on the nature of the allergen(s) of the cat flea, Ctenocephalides felis and on some of the factors that determine the development and maintenance of the allergic state. The role of immediate hypersensitivity mediated by IgE, delayed hypersensitivity and of cutaneous basophil hypersensitivity in the immunopathogenesis is discussed. Finally, data on the nature of immunologic non-reactivity is presented and the prospects for therapeutic immunologic intervention discussed.

Fleas and related disease

This article considers the clinical signs of flea allergy dermatitis, and the diagnosis and general principles of flea control for the pet and its environment.

The role of basophils in the immunopathogenesis of hypersensitivity to fleas (Ctenocephalides felis) in dogs

Biopsies taken of skin test sites from 10 dogs allergic to fleas were fixed in Karnovsky's fixative and embedded in methacrylate. One micron sections were stained with acid Giemsa for identification of basophils. This cell was identified in most biopsies taken at intervals from 1 hour to 48 hours post-injection. The proportion was highest between 4 hours and 18 hours and had substantially fallen by 48 hours. The highest number of basophils recorded as a percentage of the inflammatory infiltrate was 22.1%, with biopsies from 7 of the 10 dogs showing in excess of 10% basophils at some point. The results suggest that cutaneous basophil hypersensitivity may play an immunopathogenic role in flea-bite hypersensitivity in dogs.

Zoonotic dermatoses of dogs and cats

Zoonotic dermatoses in dogs and cats are an important cause of skin disease in human beings. In addition, human dermatoses may occasionally be transmitted to dogs and cats. The veterinarian and the physician form a critical "health care team" in the proper management of these disorders.