Figure 3.

Effect of sialoadhesin-deficiency on prion accumulation in the spleen. (a) Immunohistochemical detection of prion-specific abnormal PrP (PrP^d, brown, arrows) upon follicular dendritic cell (FDC) in the spleens of wild-type (WT) and sialoadhesin-deficient (Sn^−/−) mice. Sections counterstained with haematoxylin (blue). dpi, days post-injection with prion. (b) Paraffin-embedded tissue immunoblot analysis confirmed the presence of prion-specific, proteinase K (PK) -resistant PrP^Sc (black) upon FDC (arrows). (c) Immunoblot analysis of PK-treated spleen tissue homogenates confirmed the accumulation of high levels of prion-specific, PK-resistant PrP^Sc. After PK treatment, a typical three-band pattern was observed between molecular mass values of 20–30 000 MW, representing unglycosylated, monoglycosylated and diglycosylated isomers of PrP (in order of increasing molecular mass). Approximate molecular weight markers are indicated. (d, e) Analysis of spleen sections from Alexa-PrP^Sc-injected mice suggested that the PrP^Sc (red) was mostly associated with SIGNR1⁺ marginal zone (MZ) macrophages (d, blue, arrows), and occasionally in the red pulp (RP) and white pulp (WP; d, arrowheads) in regions in close association with CR1/CD35-expressing (green) FDC (e, arrows). No apparent differences were observed between tissues from WT or Sn^−/− mice. Dashed lines indicate the border of the MZ.