Background: An increasing number of asthma cases upon exposure to hamsters and anaphylactic reactions following hamster bites are being reported, but the allergens responsible are still poorly characterized. In the Golden hamster, male-specific submaxillary gland protein (MSP), a lipocalin expressed in a sex- and tissue-specific manner in the submaxillary and lacrimal glands, is secreted in the saliva, tears and urine. The purpose of this study was to determine if MSP is an allergen, to identify IgE-reactive proteins of different hamster species and to analyse potential cross-reactivities. Methods: Fur extracts were prepared from four hamster species. Hamster-allergic patients were selected based on a history of positive IgE-test to hamster epithelium. The IgE-reactivity of patients' sera was investigated by means of immunoblot and ELISA. IgE-reactive proteins in fur extracts and the submaxillary gland were identified using anti-MSP antibodies, Edman sequencing or mass spectrometry. MSP was purified from Golden hamster and recombinant MSP was expressed in E. coli. Results: Four patients had IgE-antibodies against 20.5-kDa and 24-kDa proteins of Golden hamster fur extract, which were identified as MSP. IgE-reactive MSP-like proteins were detected in European hamster fur extract. Three patient sera showed IgE-reactive bands at 17-21 kDa in Siberian and Roborovski hamster fur extracts. These proteins were identified as two closely related lipocalins. Immunoblot inhibition experiments showed that they are cross-reactive and are different from MSP. Conclusion: MSP lipocalin of the Golden hamster was identified as an allergen, and it is different from the cross-reactive lipocalin allergens of Siberian and Roborovski hamsters. Our findings highlight the need for specific tools for the in vitro and in vivo diagnosis of allergy to different hamster species.

Background: Immediate as well as delayed-type hypersensitivity immune reactions to pet-borne allergens are commonly observed in atopic diseases. Further on in atopic dermatitis (AD), cross-reactivity to self-proteins is discussed to contribute to the disease. Human cystatin A and the cat allergen Fel d 3 belong to the cystatin family, an evolutionary conserved protein family. The objective of the present study was to assess cross-reactivity between mammalian cystatins and to analyze T cell responses to cystatin in AD patients sensitized to pet dander. Methods: cDNA coding for dog cystatin was cloned from dog skin. Sera of 245 patients with IgE-sensitization to cat and dog dander were tested for IgE-binding to recombinantly expressed feline, canine, and human cystatin, respectively. Of these, 141 were also diagnosed for AD. Results: Cystatin-specific IgE was detected in 14.7 %(36) of patients, of which 19 suffered from AD. Within the AD patients, 9 carried measurable IgE against all three cystatins. Cystatin-sensitized AD patients did not differ from non-cystatin sensitized patients in terms of disease severity, age or total IgE levels. T cell cytokine measurements showed elevated IL-4 levels after stimulation with feline and human cystatin. Conclusion: The humoral response suggests that next to Fel d3 also the homologous protein from dog might play a role in allergy. Further on, the human cystatin appears to be capable of driving a type2 immune response in sensitized AD patients and may therefore be considered a so-called autoallergen, as it has been proposed for other evolutionary conserved proteins.

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There are many factors, other than the absence of an immune response, that are responsible for the successful transplantation of xenografts to nude mice. We have defined, in this study, the relationship between karyotype and transplantability of xenografts into nude mice, using a library of 85 tumor and normal tissue culture lines. Each of these lines had been previously passaged in tissue culture for more than 10 generations. 53 of these 85 lines were classified as diploid, whereas 32 lines were classified as heteroploid. These tissue culture lines were transplanted to groups of 4-10 unmanipulated and antilymphocyte serum (ALS)-treated nude mice and serially monitored for 12 weeks. Only 19 % of the diploid lines were successfully transplanted into unmanipulated nude mice, and only 30% were successfully transplanted into ALS-treated nude mice. In comparison, 50% of the heteroploid lines were successfully grafted into unmanipulated nude mice, and a total of 60% were successfully transplanted into ALS-treated nude ice. 12 of the 53 diploid lines can be classified as being pseudodiploid on the basis of rearranged chromosomes or other minor karyotype anomalies. 8 of these 12 pseudodiploid lines were successfully transplanted into nude mice, further strengthening the relationship between abnormal karyotype and transplantability. Tumor karyotype is an additional parameter which should be added to the variables involved in the successful transplantation of tumors to nude mice.