Figure 1.

Expression of laminin chains in human thymus. Immunofluorescence staining of human thymus cryostat sections was performed with an antiserum against the laminin isoform LN-1 which recognizes α1, β1 and γ1 chains (anti-LN-1), and with laminin chain-specific antibodies (α1–α5, β1 and β2, γ1 and γ2). No immunoreactivity was observed with the α1 chain-specific antibody. Antibodies against the α2, the α5, the β1, the β2 and the γ1 chains labelled thymic blood vessels and the subcapsular epithelium of the thymic lobules. Expression of the laminin α4 chain in the thymus seemed to be restricted to endothelial cells, as no immunoreactivity was observed at the subcapsular epithelium (arrow). Antibodies against the α3 and γ2 chains showed a different staining pattern. Both antibodies strongly labelled thymic medullary epithelial cells, whereas only faint signals were observed at the subcapsular epithelium with both antibodies (arrows). The antiserum against LN-1 detected two laminin-containing structures in the thymus: the subcapsular epithelium and endothelial basement membranes. Medullary and cortical regions are marked by M and C, respectively. (Original magnification ×45.)