Preparation and characterization of silverfish (Lepisma saccharina) extract and identification of allergenic components.
BACKGROUND
Airborne insect antigens represent important aeroallergens which have been widely investigated. Although it has been demonstrated that house dust contains significant silverfish (Lepisma saccharina) levels, none of the extracts obtained so far has been extensively characterized. Thus, we have prepared and characterized a silverfish extract and investigated its IgE-reactive components by testing the reactivity of sera from patients allergic to inhalant insect allergens.


METHODS
The extract from silverfish insect bodies was prepared by homogenizing frozen silverfish in Tris-HCl buffer. The soluble material (Sup) was filtered and the insoluble material (Ppt) was resuspended in 100 mM Tris pH 10.6. The two fractions were characterized by biochemical and immunochemical methods. IgE reactivity was investigated on both fractions before and after periodate treatment.


RESULTS
Protein content and total carbohydrates was 2 and 3% w/w for Sup and 1 and 0.3% w/w for Ppt. The SDS-PAGE profile of the two fractions showed a different pattern in the MW range of 5-175 kD. Sup and Ppt, probed with allergic sera, showed a complex pattern of IgE reactivity. When periodate-treated fractions were tested, IgE reactivity was either completely abrogated, reduced or not affected, depending on the allergic serum employed.


CONCLUSIONS
The results obtained indicate that the classic aqueous-extraction procedures that have been used up to now for other insects might not be completely satisfactory, since several allergenic components are not soluble at the normally used pH. We developed a dedicated extraction procedure allowing the detection of a certain degree of reactivity in sera negative to allergens extracted following classic procedures.
Department of Immunology, Istituto Superiore di Sanità, Rome, Italy. barletta@iss.it
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Barletta
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Puggioni
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Afferni
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Butteroni
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Iacovacci
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Tinghino
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Ariano
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Panzani
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Di Felice
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Pini
D000485:Allergens / Q000737:chemistry / Q000276:immunology*; D000818:Animals; D004391:Dust / Q000009:adverse effects*; D006801:Humans; D006969:Hypersensitivity, Immediate / Q000175:diagnosis / Q000209:etiology; D007073:Immunoglobulin E / Q000378:metabolism*; D007313:Insecta / Q000737:chemistry / Q000276:immunology*; D037102:Lectins / Q000378:metabolism; D010504:Periodic Acid / Q000494:pharmacology; D011852:Radioallergosorbent Test; D012882:Skin Tests; D014020:Tissue Extracts / Q000737:chemistry / Q000276:immunology* / Q000302:isolation & purification*
D000485:Allergens; D004391:Dust; D037102:Lectins; D014020:Tissue Extracts; D010504:Periodic Acid; D007073:Immunoglobulin E; C009288:metaperiodate