A Human Monoclonal Antibody to Cytokeratin Intermediate Filament Antigens Derived from a Tumor Draining Lymph Node

Human lymphocytes derived from a lymph node draining a primary breast adenocarcinoma were fused with the mouse myeloma P3X63Ag8.653 to generate human-mouse hybridomas secreting human monoclonal antibodies (MAbs) to tumor associated antigens (TAAs). One of the resulting human MAbs, YBB 190 (IgM) is described. Enzyme-linked immunosorbent assays (ELISA) employing membrane and cytosol fractions of human tissues demonstrated YBB 190 reactivity against cytosol but not membrane components of malignant and normal epithelial tissues. When tested by an indirect immunoperoxidase staining method against fresh frozen human tissue sections, YBB 190 reacted with malignant cells in 26 of 28 epithelial cancers and with normal epithelia in 11 different benign tissues. Preliminary western blot antigen characterization indicated that YBB 190 recognizes cytokeratin intermediate filaments, or a protein that is closely associated with cytokeratins. These data indicate that B cells with specificity for intermediate filaments are present in tumor draining lymph nodes. Our findings provide insights into the nature of potential autoimmune responses in cancer patients and suggest that improved tumor directed sensitization procedures may be required to more effectively utilize lymphocytes from tumor draining lymph nodes to generate therapeutically useful human MAbs to TAAs.