Are CNA.42 and FBC-B1 directed against Are CNA.42 and FBC-B1 directed against ovine follicular dendritic cells?ovine follicular dendritic cells?

IntroductionIntroductionLike the variant of Creutzfeldt Jakob (vCJD) in human and bovine spongiform encephalopathy (BSE) in cattle, natural scrapie in sheep is a transmissible spongiform encephalopathy (TSE) caused by prions (PrPSc). The presence of PrPSc at early time points in tonsils suggests that tonsillar biopsies could have a role in the diagnosis at the preclinical stage of the disease. In lymph organs, follicular dendritic cells (FDCs) seem to be the major site of cellular prion protein expression and the principal site of infectious agent accumulation.

ObjectiveObjectiveIn this study, we compare the ability of FDC B1 and CNA.42 monoclonal antibodies to recognize ovine FDCs.

Material and MethodsMaterial and MethodsPalatine and pharyngeal tonsils were removed from 4 - 6 month old sheep and processed for classical histology, immunocytochemistry and confocal analysis.

ResultsResultsWith FDC B1, the fluorescence microscopy analysis reveals a clearly positive network inside the germinal center of both immunostained tonsils whereas CNA.42 only reacts with pharyngeal tonsil follicular dendritic network.

Toppets V., J. Piret, M. Minne, L. Grobet and Antoine N.Faculty of Veterinary Medicine, Department of Morphology and Pathology, Laboratory of Animal Histology and Embryology, University of Liege, Belgium.

ConclusionsConclusions These results allow us to postulate that the antigen recognised by CNA.42 is not expressed by follicular dendritic cells from all lymph organs. Obtained negative stainings must thus be interpreted with full knowledge of the facts. The antigen detected by FDC B1 seems to be more ubiquitous.

PerspectivesPerspectivesOther lymph organs, such as lymph nodes from digestive and respiratory tracts, will be studied to inquire whether the observation is organ specific or not. Similarly, palatine and pharyngeal tonsils from other species will also be compared.

Hematoxylin Eosin StainingsHematoxylin Eosin Stainings FBC B1 ImmunostainingsFBC B1 Immunostainings CNA.42 ImmunostainingsCNA.42 Immunostainings

Pharyngeal Pharyngeal TonsilsTonsils

Palatine Palatine

TonsilsTonsilsFDC network FDC network

negative labellingnegative labelling

►Lympho epithelial tissue, ►respiratory epithelium,►epidermoid epithelium , ► follicles, ► mantle zone, ► germinal center, ► crypt.