2021 Volume 55 Issue 4 Pages 151-161
Antigen-presenting cells characterised by the expression of MHC class II molecules play a crucial role in differentiating and activating helper T cells at lymphoid organs. We attempted to establish an immunohistochemical staining technique for the detection of MHC class II-expressing cells in Japanese flounder to study the localisation of these cells in tissues. We produced a specific antibody against the α chain peptide of MHC class II. The antibody reacted to the recombinant protein of the α2 segment of the class II molecule, the native molecule of the class II α chain in soluble proteins from the spleen and in membrane proteins from intraperitoneal infiltrated cells. Immunohistochemical staining using the antibodies could be utilised for the detection of MHC class II-expressing cells in paraffin-embedded tissue specimens. MHC class II-expressing cells were found in various organs and tissues such as the spleen, kidney, thymus, intestine, stomach, liver, heart, gills, skin, olfactory organs, and brain. The immune-positive cells showed an elongated- or rounded-shape. Considering our observations of morphological features and tissue localisation along with previously published information, we suggest that the MHC class II-expressing cells are dendritic cells, macrophages, B cells, microglia, and epithelial cells that have been considered antigen-presenting cells.
