MAPPING OF 6 MONOCLONAL ANTIBODIES TO HUMAN FACTOR IX

In order to map the regions of human factor IX recognized by monoclonal antibodies we have inserted random fragments of the coding region of the cDNA for human factor IX into the lambda phage expression vector, lambda gtll. The resultant recombinant phage were screened with monoclonal antibodies, the immunoreactive phage were isolated, and the DNA of the inserted fragment was sequenced to determine which amino acids were immunoreactive. This data, coupled with data obtained from the use of specific fragments of human factor IX expressed in E. coli from a T7 phage promoter, has allowed us to map the location of several epitopes on the surface of the factor IX molecule. In those cases where the antibodies are specific for human factor IX, additional narrowing of the epitope is possible by comparing the amino acid sequence of human factor IX to the bovine molecule. Six monoclonal antibodies from 3 different laboratories have been mapped. The immunodominant epitopes appear to be the amino terminus of the activation peptide, the amino terminus of the heavy chain and the epidermal growth factor domains.