Untersuchungen der Expression von Neurotrophinen und Neurotrophin-Rezeptoren auf murinen B-Zellen im Knochenmark und in der Milz von C57BL/6

Neurotrophins are essential for survival, proliferation and differentiation for neuronal cells. The neurotrophins are NGF, BDNF, NT-3 and NT-4/5. The effects are mediated by two families of neurotrophin-receptors: the Tyrosinkinase-receptors (trk-receptors) mediated survival, proliferation and differentiation. They only bind with highly affinity certain neurotrophins (for example: NGF is the natural ligand of trkA). It exists three classes of trk-receptors: trkA, trkB and trkC. The trk-receptors are exprimited in different isoforms, some of these isoforms contain no catalytic tyrosinkinase-domain. Another neurotrophin-receptor is the pan-neurotrophin-recetor p75. The p75-receptor mediates different functions: in presence of trk-receptors the p75-recetor causes survival, proliferation and differentiation; in absence of the trk-receptos p75 induces apoptosis. In the last twenty years neurotrophins and their receptors could detected in extraneuronal cells, forthermore in T- and B-lymphocytes. Regard to the b-cells they exist different messages: some authors show us, that b-cells exprimites all neurotrophins and all neurotrophin-receptos, other authors prove only an trkA- and p75 expression of b-cells. We could show with molecular methods (including real-time PCR), that immature and mature b-cells exprimites all neurotrophins and all neurotrophin-receptors. Only the trkB-receptor is exprimited as an isoform: the trkBgp95. This isofoms doesn´t contain a catalytic domain. The dominant neurotrophin of immature b-cells in bone marrow is BDNF. NT-3 and NGF are the dominant neurotrophins of mature b-cells in spleen.