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 (IalphaI) 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 IalphaI HC and HA in adult mouse tissues. An immunohistochemical method using a rabbit polyclonal antibody raised against mouse IalphaI heavy-chain peptide and a specific probe for HA (biotinylated HA-binding protein) was used to demonstrate an immunolocalization of IalphaI HC and HA. Distribution and localization of HA was of three types, namely, colocalization with IalphaI HC itself (cartilaginous tissue and ovary), localization around IalphaI HC immunostaining (lung, intestine and skeletal muscle), and localization at a small distance from IalphaI HC or a different distribution pattern (brain, liver, skin and kidney). These results indicate that IalphaI HC could function as an HA-rich matrix stabilizer on the cells of cartilage and maturing ovary, in which IalphaI HC shows colocalization with its predominant ligand, HA.