[Continuing education. Restrictive respiratory disorders].
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Diagnosis, Differential↗
Biomedical subjects
H Prelicz
Publications and source records attributed to H Prelicz.
Structure, antigenic determinants of some clinically important insect allergens: chironomid hemoglobins.
Determination of the molecular structure and properties of allergens that elicit severe immediate-type hypersensitivity diseases in humans and a knowledge of the structure of their antibody-binding sites should provide new insight into the pathogenetic mechanisms of allergic diseases. Monomeric and homodimeric hemoglobins (CTT I to X) have been identified as potent allergenic components of Chironomidae, a family of Diptera. Immunologic investigations of peptides of three of these hemoglobins (CTT IV, CTT VI, and CTT VIII) showed that human antibodies of the E and G classes recognize at least two different sites within each molecule. Individual hemoglobin peptides were aligned with homologous regions of chironomid hemoglobin CTT III, whose tertiary structure has been determined by x-ray analysis at a resolution of 1.4 angstroms. The antigenic site CTT IV(91 to 101) showed the following characteristics: (i) seven polar or hydroxylated amino acids, from a total of eleven, occupying predominantly superficial regions; (ii) the property of linkage to other molecules by hydrogen bonds or solvent clusters; and (iii) high thermal mobility factors. In contrast, peptide CTT IV(102 to 108), which does not bind human antibodies, contained no polar amino acids and had low thermal mobility factors. These results support the idea that the antigenicity of clinically relevant proteins is related to regions with a predominance of polar amino acids and with low energy barriers between different conformations, which allow high flexibility, including site-specific adaptation in antibody binding.
Allergens↗
Persistence of hemoglobin allergenicity and antigenicity during metamorphosis of Chironomidae (Insecta: Diptera).
Chironomid hemoglobins are potent allergens. The allergenic and antigenic activities of these hemoglobins are studied with the help of RAST, RAST inhibition and double immunodiffusion. Human as well as rabbit antisera were used. It was shown that hemoglobins are the main antigenic/allergenic components in extracts of Camptochironomus tentans larvae. Furthermore, immunological cross-reactivity among larvae, pupae and adult midges of this species are shown to be due to the existence of hemoglobin antigenic determinants in all developmental stages of this insect.
Animals↗
Evidence for haemoglobins as common allergenic determinants in IgE-mediated hypersensitivity to chironomids (non-biting midges).
Chironomids (non-biting midges) are known to cause IgE-mediated hypersensitivity in man. This study compares the cross-reactivity between the chironomid midge Cladotanytarsus lewisi ('green nimitti'), a widespread cause of allergy in the Sudan and Chironomus riparius (= thummi, CTT) where larvae are used as pet fish food and where haemoglobins were previously shown to be major allergens. As with C. riparius, immature forms of C. lewisi also contain allergenic material since skin test responses to larval, pupal and adult extracts were obtained in Sudanese individuals. Crossed radioimmunoelectrophoresis of the C. lewisi larval and pupal extracts indicate that they contain a higher proportion of the allergenic fractions than adults. Further evidence of common allergen determinants between C. lewisi and C. riparius were obtained by the demonstration of positive skin-prick tests, in Sudanese patients, to extracts of larval, adult and isolated haemoglobin extracts of C. riparius. Cross-reactivity between C. lewisi and C. riparius was also demonstrable by RAST inhibition studies. A dose-dependent inhibition was observed using both the C. lewisi adult midge RAST and the C. riparius haemoglobin RAST, the two respective antigens, and sera from individuals hypersensitive to either C. lewisi or C. riparius. Due to the immunological cross-reactivity found between these distantly related species, we conclude that chironomids should be seen as significant environmental and occupational allergens.
Allergens↗
Common antigenic determinants of haemoglobin as basis of immunological cross-reactivity between chironomid species (Diptera, Chironomidae): studies with human and animal sera.
Chironomids, of which approximately 10,000 species exist, are reported to cause severe immediate type allergic diseases in man. In the present study, immunological cross-reactivity between 14 chironomid species from different continents was proven by RAST inhibition, double immunodiffusion and a new allergoprint technique, based upon PAGE separation of insect crude extracts. Using isolated chironomid haemoglobins and sera of sensitized persons, as well as rabbit antibodies against larval crude extract or against the haemoglobin fraction of Chironomus thummi, it could be proven that cross-reactivity derives at least predominantly from haemoglobin components with common antigenic determinants in the different species.
Animals↗