Eosinophils in the zebrafish: prospective isolation, characterization, and eosinophilia induction by helminth determinants.

Eosinophils are granulocytic leukocytes implicated in numerous aspects of immunity and disease. The precise functions of eosinophils, however, remain enigmatic. Alternative models to study eosinophil biology may thus yield novel insights into their function. Eosinophilic cells have been observed in zebrafish but have not been thoroughly characterized. We used a gata2:eGFP transgenic animal to enable prospective isolation and characterization of zebrafish eosinophils, and demonstrate that all gata2(hi) cells in adult hematopoietic tissues are eosinophils. Although eosinophils are rare in most organs, they are readily isolated from whole kidney marrow and abundant within the peritoneal cavity. Molecular analyses demonstrate that zebrafish eosinophils express genes important for the activities of mammalian eosinophils. In addition, gata2(hi) cells degranulate in response to helminth extract. Chronic exposure to helminth- related allergens resulted in profound eosinophilia, demonstrating that eosinophil responses to allergens have been conserved over evolution. Importantly, infection of adult zebrafish with Pseudocapillaria tomentosa, a natural nematode pathogen of teleosts, caused marked increases in eosinophil number within the intestine. Together, these observations support a conserved role for eosinophils in the response to helminth antigens or infection and provide a new model to better understand how parasitic worms activate, co-opt, or evade the vertebrate immune response.

[Comparative immunofluorescent-histological investigations on 7 nematode species in respect to its antigenic properties for differential diagnosis of nematode infections (author's transl)]. / Vergleichende Immunfluoreszenz-histologische Untersuchungen an 7 Nematoden-Spezies in bezug auf ihre Antigeneigenschaften zur Differenzierung von Nematodeninfektionen.

Five nematode species of the Onchocercidae family and one from the Strongylidae and Trichuridae family were tested as antigen in the immunofluorescence test (IIFT) against reference sera from six nematode infections. The localisation of the cytosomal antigen antibody-reaction in the IIFT which was described on D. Viteae, was found to be the same for B. malayi, B. pahangi, L. carinii, O. volvulus and A. caninum. This test, just as egg membrane crude preparations of 5 nematodes from the Onchocercidae family, could not differentiate between W. bancrofti, onchocerciasis, loiasis and D. perstans sera. The cuticular fluorescence of five Onchocercidae species, which was observed only in frozen sections, appeared only with W. bancrofti-filariasis and onchocerciasis sera. T. spiralis larvae antigen exhibited only cuticular fluorescence in the frozen section, but in the case, however, against all reference sera. Trichinellosis patients' serum reacted on the other hand only with T. spiralis antigen. Uterine microfilaria from B. malayi, L. carinii, O. volvulus and D. viteae could differenciate species specifically between reference sera.

[Immunization against Capillaria hepatica: the effects of primary infections, x-irradiated stages, non-embryonated eggs, and soluble egg extracts (author's transl)]. / Immunisierung gegen Capillaria hepatica: Die Wirkung von Erstinfektionen, röntgenattenuierten Stadien, nicht embryonierten Eiern und löslichen Eiextrakten.

The influence of primary infections with embryonated infective eggs or with X-irradiated infective eggs, and of non-embryonated eggs, and egg homogenate extracts on challenge infections with Capillaria hepatica was investigated. The worm reproductivity was significantly suppressed in a sublethal challenge infection given 11 days after a primary infection of Mastomys natalensis with 50, 150, 400, and 800 eggs per animal. The administration of 600 X-irradiated (2.2 Krd) embryonated eggs 36 days before challenge as well as an intraperitoneal injection of non-embryonated eggs 12, 10, 8, 6, 4, and 2 days before challenge (simulating the egg production of a normal infection) also reduced significantly the egg production of a weak (50 eggs/ animal) infection. No effect was observed on a moderate challenge (300 eggs/animal). The effect was not markedly enhanced by the repeated administration of X-irradiated eggs or by the combination of X-irradiated infective eggs and non-embryonated eggs. Immunization of mice with soluble egg extracts resulted in significant reduction of egg production determined 60 days after challenge. Two hundred and thirty eggs of C. hepatica/g body weight proved to be a lethal infection dose for M. natalensis. The animals died between 20 and 35 days after infection. After single infections with 50, 150, 400, or 800 eggs per animal the mortality of Mastomys challenged 36 or 52 days later was reduced to 0--30%. Using X-irradiated embryonated eggs for immunization only repeated administration led to protection in 70 to 80% of the animals. About 40% of the animals could be protected by the intraperitoneal injection of non-embryonated eggs. If death occurred it was delayed. The combination of X-irradiated stages and eggs did not enhance the protection.

Serology of Capillaria philippinensis infection: reactivity of human sera to antigens prepared from Capillaria obsignata and other helminths.

The reactivity of sera from 151 confirmed human cases of Capillaria philippinensis infection was examined by double diffusion and indirect hemagglutination (IHA) tests chiefly against Capillaria obsignata antigen because of the present unavailability of C. philippinensis antigen. Antigens from additional parasites and other human and animal sera representing a variety of helminthic infections were used for comparison. Of 71 pre-treatment human sera, 56.3% were reactive by double diffusion test and 85.9% by IHA test (titer greater than 1:16) with C. obsignata antigen. C. philippinensis sera were also reactive with Trichinella spiralis and Trichuris vulpis antigens but not with Schistosoma japonicum antigens. Sera from other infections such as with T. spiralis, T. vulpis, and S. japonicum were also reactive with C. obsignata antigen but sera from Trichuris trichiura infection were not. With C. obsignata antigen, IHA titers in human C. philippinensis sera are apparently not related to clinical severity of the disease; the titers remain at fairly stable levels during the course of the illness but may tend to decrease after chemotherapy. The cross-reactivities observed dictate caution in the use and interpretation of any serologic procedure for human intestinal capillariasis; nevertheless, the IHA test using C. obsignata antigen may be a useful addition tool in the study of C. philippinensis infection both for clinical and epidemiologic purposes especially when the efficiency of stool examination is decreased by changes in the reproductive activity of the helminth.