E. Benjamini

Histologic studies of guinea pig skin: Different stages of allergic reactivity to flea bites☆

Abstract A definite sequence of skin reactions occurs when guinea pigs are exposed to flea bites. The sequence is composed of stages that are observed at the bite sites and can be classified in terms of allergic phenomena. This study presents a sequential morphologic analysis of these allergic stages in terms of histopathologic events. When the different types of skin sensitivity in guinea pigs were defined both by macroscopic and microscopic characteristics, the following stages were noted: 1. I. Induction stage, during which no abnormal macroscopic or microscopic changes occurred in the skin; 2. II. Stage of delayed skin reactions only, characterized by intense mononuclear infiltration at the vicinity of the bite site some 24 hours following the bite; 3. III. Stage of immediate and delayed reactions, immediate reactions appearing 20 minutes after the bite and characterized by an eosinophilic infiltration; the delayed reaction appearing within 24 hours, characterized by mononuclear infiltration; 4. IV. Stage of immediate reactivity only, the reaction appearing 20 minutes after the bite and characterized by an infiltration of eosinophils at the bite site; 5. V. Stage of nonreactivity resulting from desensitization, wherein no skin reactivity was observable and no cellular abnormalities occurred.

Skin Reactivity in Guinea Pigs Sensitized to Flea Bites The Sequence of Reactions

Summary Experimental evidence is presented which demonstrates the occurrence of a definite sequence of events in the skin reactions of guinea pigs following repeated exposure to flea bites. The sequence was: I—induction of sensitivity; II—predominately delayed skin reactivity; III—delayed and immediate responses; IV—predominately immediate reactivity; V—non-reactivity.

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

Abstract 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.

Immunochemical studies on collagen—II Antigenic differences between guinea pig skin collagen and gelatin

Abstract Immunization of rabbits with guinea pig skin collagen elicited antibody with specificity for α2-CB1, a cyanogen bromide derived peptide from the amino-terminal region of α2, whereas, the α1 chain and peptides derived from it by cleavage with cyanogen bromide were essentially devoid of antigenic activity. Immunization with gelatin (denatured collagen) resulted in the formation of antibodies with specificities for α2-CB1 as well as to a portion of the α1 chain. Antiserum prepared against native collagen contained antibodies which reacted with antigens detected only in gelatin. The denaturation accompnying the transformation of collagen to gelatin is believed to expose immunogenic and antigenic sites previously hidden in the native molecule.

The specificity of antibodies to a peptide determinant of the tobacco mosaic virus protein induced by immunization with the peptide conjugate.

Abstract An antigenic decapeptide having the sequence Thr-Thr-Ala-Glu-Thr-Leu-Asp-Ala-Thr-Arg representing residues 103–112 of the tobacco mosaic virus (TMV) protein, and the C-terminal pentapeptide portion of the decapeptide were conjugated to succinylated bovine serum albumin. Rabbit antibodies produced following immunization with these conjugates were exhibited to bind with the homologous peptides, with TMV protein and with peptides which bind with anti-TMV-protein. The results indicate that the specificity of the receptor on immunocompetent cells parallels the specificity of the antibodies produced.

Allergy to flea bites. III. The experimental induction of flea bite sensitivity in guinea pigs by exposure to flea bites and by antigen prepared from whole flea extracts of Ctenocephalides felis felis

Abstract Guinea pigs were sensitized to flea bites by previous exposure to Ctenocephalides felis felis. Delayed reactions appeared at from 5–7 days following daily exposures. Two to 5 days following the appearance of delayed reactions, the animals showed both delayed and immediate types of reactivity. The induction of sensitivity by flea bites was independent of the number of fleas biting. Sensitivity to flea bites induced either by intradermal injection of whole flea extract in saline or by flea bites was systemic and appeared to be an allergic phenomenon. Sensitivity of guinea pigs to flea bites was induced by intradermal injections of whole flea extracts in saline. Guinea pigs injected intradermally with whole flea extract reacted to flea bites. Conversely, when sensitized by flea bites, they reacted to challenge with the extract. While sensitivity to flea bites induced by flea bites required a latent period of 5–7 days, sensitivity to flea bites induced by whole flea extract required 10–14 days.

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.

Abstract 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 Rf of 0.6 in butanol-acetic acid, and migrating toward the anode on paper electrophoresis at pH 2.3.

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☆

Abstract 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 hosts skin, and the role of the hosts skin in the induction of flea-bite hypersensitivity is demonstrated.