Flea Bite Hypersensitivity Research Articles

Putative salivary allergens of the cat flea, Ctenocephalides felis felis

The cat flea, Ctenocephalides felis felis, is the major initiator of flea bite hypersensitivity in dogs. Previous analyses of whole extracts of the flea and flea salivary secretions have failed to identify the allergens responsible. We dissected >2000 salivary glands from adult female fleas, extracted them into buffered saline containing protease inhibitors and fractionated the extract using gel permeation HPLC. Dogs were classified as hypersensitive to fleas (flea-feeding positive, FF+) or insensitive (flea-feeding negative, FF−) using a provocative test with live fleas. The allergenicity of the components of the salivary gland extract was tested by intradermal injection of samples of the column eluates. Dogs were also injected intradermally with a sample of whole salivary gland extract, and with histamine as a positive control. Negative control injections consisted of eluate from the column collected prior to fractions containing any protein. The skin of FF− dogs either did not respond or had a minimal response (a bleb ∼2 mm larger than the injection blebs at the negative control injection sites) to all fractions and to the whole extract; histamine control injections produced positive responses (defined as wheals 5 mm greater than the blebs at the negative control injection sites) in all dogs. The skin of three of the nine FF+ dogs reacted positively to injection of a fraction containing protein/s with apparent MW 40k. Five other FF+ dogs reacted positively to the fractions containing proteins with apparent MW 12-8k. A single dog responded with very large, red wheals to injection of both the ∼MW 40k and MW12-8k fractions. These findings suggest that proteins with apparent MW 40k and MW 12k-8k are important in flea bite hypersensitivity. This work also supports a previous finding that mice which had been exposed to flea bites had antibodies to proteins with ∼MW 40k that were detected in salivary secretions of the flea.

Salivary antigens of the cat flea, Ctenocephalides felis felis.

The cat flea, Ctenocephalides felis felis, is the major cause of flea bite hypersensitivity (FBH) in dogs and cats, yet little progress has been reported on identifying the antigens responsible. We obtained flea salivary antigens by washing secretions from containers probed by the mouthparts of fleas, and by extracting whole flea salivary glands. Mice were exposed to feeding fleas to generate antibodies to salivary antigens injected in vivo. The sera were tested for antibodies against the salivary antigens described and against a whole flea extract; in indirect ELISA, antibodies to salivary secretions were detected in 60% of the sera from mice exposed to feeding fleas. These sera identified four protein bands at apparent MW 56, 54, 42 and 40 K which corresponded to prominent protein bands in whole salivary gland extracts identified by protein staining after SDS-PAGE. Fixed sections of whole fleas exposed to the antisera showed that only structures within the salivary glands were identified. The salivary secretions and gland extracts are now being used to study immune responses of dogs suffering from FBH.

Identification of mast celis in buffy coat preparations from dogs with inflammatory skin diseases

Summary In 100 dogs with 4 inflammatory dermatologic diseases, buffy coat preparations from edta-treated blood samples were examined cytologically. Fifty-four dogs had atopy, 26 had flea-bite hypersensitivity, 17 had sarcoptic mange, and 3 had food allergy. Twenty-eight dogs had 2 or more concurrent skin diseases; most of these had secondary pyoderma. Dogs did not have mast cell tumors. Thirteen samples contained 1 or more mast cells/4 slides reviewed. This study revealed that dogs with inflammatory skin diseases can have a few to many mast cells evident on cytologic examination of buffy coat preparations.

Miliary dermatitis in the cat

Miliary dermatitis is a cutaneous response to disease states seen in the cat. It is not in itself a diagnosis. Conditions which may lead to miliary dermatitis lesions can be divided into hypersensitivity disorders, parasitic causes, infections and miscellaneous causes. A thorough investigation frequently leads to a diagnosis which enables specific therapy. Symptomatic, empirical therapy is less satisfactory and may in the long term cause side effects, The single most important cause of miliary dermatitis in the UK and elsewhere in the world is flea-bite hypersensitivity. Other important and increasingly recognised causes include atopy and food hypersensitivity. With determination and a thorough approach to diagnosis the number of idiopathic cases of miliary dermatitis are small.

The role of basophils in the immunopathogenesis of hypersensitivity to fleas ( [formula omitted]) 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.

Lesions of experimental flea bite hypersensitivity in the dog.

Hypersensitivity to fleas was induced in flea-naive dogs by controlled challenge exposure to virgin fleas. By week 10 of the investigation, immediate (15 minute) and delayed (24-48 hours) responses could be elicited in the skin by flea bites. Histologically, the immediate response consisted of edema and eosinophils which sometimes overlapped with a delayed inflammatory response comprised of perivascular lymphocytes and fewer histiocytes. These inflammatory patterns correlated with type I or immediate, and type IV or cellular, allergic reactions. The combined immediate and delayed responses to fleas in the dog are as observed by other investigators in man and guinea pigs.

The Role of Collagen in the Induction of Flea Bite Hypersensitivity

Summary Salt-soluble and acid-soluble collagens were isolated from guinea pig skin following bites of fleas, and were shown to possess the capacity to induce flea bite hypersensitivity upon injection into recipient guinea pigs. Less salt-soluble collagen was required for induction of sensitivity than was acid-soluble collagen. Flea hapten associated with salt-soluble collagen did not hinder the latter's in vitro reconstitution. The in vitro reconstituted product served as a better carrier for the hapten than the nonreconstituted form.

The physiological and biochemical role of the host's skin in the induction of flea-bite hypersensitivity. I. Preliminary studies with guinea pig skin following exposure to bites of cat fleas

Activity related to flea-bite hypersensitivity could be recovered from skin fractions of guinea pigs following flea bites. The activity resided in nonsaline-extractable as well as in saline-extractable portions. The former could induce flea-bite hypersensitivity; the latter could induce sensitivity only with adjuvants. The adsorption of materials secreted by the flea to elements of the host's skin, and the role of the host's skin in the induction of flea-bite hypersensitivity is demonstrated.

Allergy to flea bites. V. Preliminary results of fractionation, characterization, and assay for allergenic activity of material derived from the oral secretion of the cat flea, Ctenocephalides felis felis

Preliminary investigations of material obtained from in vitro-collected oral secretion of fleas have revealed several substances showing allergenic activity related to flea-bite hyper-sensitivity. The oral secretion was found to contain peptides, amino acids, aromatic compounds, phosphorus, and fluorescent materials. Gel filtration fractionation of the material showed that its allergenic activity was produced by a high-molecular-weight fraction (molecular weight of about 4000–10,000) and by a highly fluorescing aromatic fraction of molecular weight probably below 1,000. The low-molecular-weight aromatic fraction was further fractionated and its allergenic activity is suspected to be associated with a bright blue fluorescing material having an R f of 0.6 in butanol-acetic acid, and migrating toward the anode on paper electrophoresis at pH 2.3.

Allergy to flea bites. IV. In vitro collection and antigenic properties of the oral secretion of the cat flea, Ctenocephalides felis felis (Bouché)

The in vitro collection of oral secretion of cat fleas Ctenocephalides felis felis and the allergenic properties of the collected material are described. The reported experiments demonstrate that the oral secretion contains a substance or substances responsible for the induction of flea-bite hypersensitivity, and that this substance or substances are haptenic in nature.