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Abstract :
[en] Follicular dendritic cells (FDCs) are unique immunological accessory cells located in the light and dark zones of the germinal centres in lymph follicles. Characterized by long branching processes forming a three-dimensional network, FDCs create particular microenvironments for germinal centre B and T cells and contribute to the maturation of B cells into memory cells. An involvement of the FDCs is suspected in various disorders affecting lymphoid tissues, malignant lymphoma or in some viral diseases. Moreover, in prion diseases, FDCs seem to be the major sites of extraneuronal cellular prion protein expression and the principal sites of the infectious agent accumulation in lymph organs.
Because no antibody commercially available was specific to bovine FDCs, a new monoclonal antibody directed against bovine FDCs (FDC-B1) has been produced and characterized in our laboratory. The antigen detected by FDC-B1 is expressed on FDC surfaces in ruminant (bovine, ovine and caprine) lymphoid organs. This protein seems to be a membrane glycoprotein of more or less 28 kDa whose sequence will be soon determined. Moreover, FDC-B1 can be used in various applications: immunofluorescence, immunoperoxidase, immunogold labellings and western blotting.
FDCs are potential targets for therapy or prophylaxis in natural TSEs, such as bovine spongiform encephalopathies and scrapie. Thus, it appears of great interest to identify bovine and ovine FDCs in routine lymphoid tissues sections. An other application of this antibody to immunofluorescence histochemistry techniques will enable the study of possible direct contacts between bovine FDCs and nerve endings and thus clarify prions neuroinvasion scheme in the case of BSE and scrapie.