Genetic polymorphism of the H1 subunit of inter-alpha-trypsin inhibitor.

Inter-alpha-trypsin inhibitor (ITI) consists of 3 subunits (H1, H2 and L) which are encoded by 3 distinct genes. We attempted to prepare the subunit-specific monoclonal antibodies to identify the subunit carrying ITI polymorphism. Three monoclonal antibodies which were specific against each of these 3 subunits (ITI H1, ITI H2 and ITI L) were selected. ITI types could be detected by anti ITI H1 antibody, but not by anti ITI H2 or anti ITI L antibodies. From the result, it was proved that ITI polymorphism originates from the ITI H1 gene products, therefore we propose to call this system ITI H1 polymorphism.