Detailed localization of heparan sulfate (HS) in spleen (rat)

Stain: Immunofluorescence of Alexa 594 red labeled single chain antibody 3C3 for heparan sulfate (HS). The antibody stains HS epitopes of the meshwork of reticulum cells and the basal membrane of blood vessels. A: survey white pulp spleen. B: marginal sinuses between PALS area and red pulp. C: red pulp with sinusoids. (1) central arteries in the T cell area of the PALS (2). The B cell area in the follicle is localised in (3). Note the sharply demarcated and well-stained area of the marginal sinuses (4) bordering between red and white pulp. The reticular meshwork (splenic cords, Billroth) and the sinusoids in the red pulp (5) are stained strongly in contrast to the sparsely staining in the white pulp area. The heparan sulfate molecules are expressed as proteoglycans located at the cell surface and in the extracellular matrix. HS chains are involved in binding and modulation of proteins like growth factors and cytokines. The differential expression of HS epitopes in the spleen is thought to create a unique environment specialized for optimal functioning of lymphoid cells.