[Immune mechanism of rats on Nippostrongylus brasiliensis in vitro (author's transl)].

The influence of humoral and secretory antibodies as well as cell supplements on Nippostrongylus brasiliensis was tested in vitro. Adult Sprague-Dawley-rats approximately 12 weeks of age were used in these experiments. For the in vitro tests the following culture media were used: 25% chicken-embryo-extract, sodium casein, pig liver extract and rat serum for the larval stages. The medium for the cultures of adult N. brasiliensis consisted of 5% yeast extract, 15% casein, 30% Krebs-Ringer-solution and 50% rat serum. Secretory antibodies were isolated from the rinsing fluid of the rat intestines by high pressure filtration (10 to 15 micron), then cleaning of the fluid through a Sephadex G 15 column and finally narrowing down through collodene capsules. Mast cells were isolated from the peritoneal cavity by Ficoll-gradient-centrifugation. Various test series were conducted with the addition of serum or secretory antibodies of repeatedly infected and immune rats to the medium. In these tests there was never a difference in the influence on growth nor a higher mortality rate of larval or adult N. brasiliensis in contrast to cultures where serum and secretory antibodies of non-infected animals were used. A 100%, degranulation of mast cells from infected rats occurred already within 14 to 22 hours in the cultures of adult N. brasiliensis. Variations were not noticed in the influence on the viability of N. brasiliensis kept in media for 10 days without or with cell supplements as well as sera of infected or not infected rats. The results from our experiments demonstrated that there was no variation in the influence on the development and a higher mortality rate of the larval stages and adult Nippostrongylus in media containing either sera and secretory antibodies of infected or not infected rats.