Immunolocalization of hyaluronic acid and inter-alpha-trypsin inhibitor in mice

The direct interaction of hyaluronic acid (HA) and heavy chain (HC) of the inter-alpha-trypsin inhibitor (I alpha I) family plays a critical role in the organization and stabilization of the extracellular matrix. The aim of the present investigation was to elucidate the distribution of the I alpha I HC and HA in adult mouse tissues. An immunohistochemical method using a rabbit polyclonal antibody raised against mouse I alpha I heavy-chain peptide and a specific probe for HA (biotinylated HA-binding protein) was used to demonstrate an immunolocalization of I alpha I HC and HA. Distribution and localization of HA was of three types, namely, colocalization with I alpha I HC itself (cartilaginous tissue and ovary), localization around I alpha I HC immunostaining (lung, intestine and skeletal muscle), and localization at a small distance from I alpha I HC or a different distribution pattern (brain, liver, skin and kidney). These results indicate that I alpha I HC could function as an HA-rich matrix stabilizer on the cells of cartilage and maturing ovary, in which I alpha I HC shows colocalization with its predominant ligand, HA.