Initial characterization of an anti-CD5 monoclonal antibody obtained from leukemic cells infiltrating lymphocytes.

BACKGROUND AND METHODS

CD5 is a monomeric glycoprotein expressed on normal and malignant T cells and on chronic lymphocytic leukemia cells. Murine anti-CD5 monoclonal antibodies (MAbs) were obtained using T cell lines, thymocytes, and blast cells from acute T lymphoblastic leukemia as immunogen. In the present report we describe an anti-CD5 MAb obtained from hybridization of mouse spleen lymphocytes immunized with blast cells from a patient with plasmocytoma who underwent leukemic transformation.

RESULTS AND CONCLUSIONS

We demonstrate that this MAb arises from the CD5 determinant of lymphocytes disseminated among the leukemic cells. We present initial characterization of this MAb, which may represent a new CD5 epitope. Potentially, due to its efficient internalization through the cell membrane, this MAb might be used to deliver toxins to immunocompetent T lymphocytes for prevention of acute graft-versus-host disease (aGVHD) after bone marrow transplantation.