Neurotrophin receptor-like proteins in the bovine (Bos taurus) lymphoid organs, with special reference to thymus and spleen.

Increasing evidence suggests that neurotrophins could regulate immune functions acting directly or indirectly on immunocompetent cells. The indirect pathway involves stromal cells of the primary and secondary lymphoid organs. In the present study the occurrence of Trk proteins (TrkA, TrkB and TrkC), regarded as the high-affinity signal-transducing receptors for neurotrophins, was investigated in cow lymphoid organs using immunohistochemistry. The thymus and spleen of both fetal and adult animals, and the palatine tonsils, lymph nodes and Peyer's patches of adult animals, were analysed. Unidentified cells displaying TrkA-like immunoreactivity were found in the fetal thymus, whereas those expressing this protein in the adult gland were identified as epithelial cells. In the spleen, immunoreactive TrkA was observed in cells of the white pulp. TrkB immunoreactivity in both fetal and adult thymus and spleen was localized in monocyte/macrophage cells. As a rule, TrkC was absent from the thymus and the spleen independent of the animal's age. Different types of stromal cells, but never the lymphocytes themselves, displayed TrkA, TrkB, or TrkC immunoreactivity in the other lymphoid organs analysed. As in other vertebrate species, Trk proteins in the lymphoid organs of the cow were localized in the stromal, non-lymphoid cells, thus suggesting that neurotrophins might regulate the immune function acting indirectly on lymphocytes.

[Frequency of Diphyllobothrium sp. infection in Argentine wild carnivores]. / Frecuencia de infección por Diphyllobothrium sp. (Cestoda: Diphyllobothriidae) en carnívoros silvestres de Argentina.

With the aims to determine the infection frequency by tapeworms of Diphyllobothrium genus 30 samples from captive wild carnivores were analyzed. A 30% of the animal analyzed was positive to the infection. Whereas the family Procionidae has a high percentage of positivity (60%), Canidae have lower infection ratio (20-25%). The accuracy for the diagnosis of Diphylobothrium was made by the morphology of scolex, proglottids and eggs. This is the first report of the parasite presence in Argentine wild carnivores.