An Approach for Characterization and Purification of a Human Monoclonal Hybridoma Antibody

An IgG human-human monoclonal hybridoma antibody, AML-19, reactive with human myeloid cells of non-malignant and malignant origin has been produced by fusion of blood mononuclear cells from a patient with acute myeloid leukemia (AML) and the human B-lymphoma cell line RH-L4. The monoclonal antibody (MAb) AML-19 was purified from hybridoma supernatant by primarily anion-exchange chromatography, in order to separate the AML-19 MAb from contaminating immunoglobulin (Ig), e.g. bovine Ig and MAb derived from the parental fusion partner, and followed by immunoaffinity chromatography. This purification method gave the highest yield and purity of the AML-19 MAb. The isoelectric point (pI) of the MAb was estimated to be 5. Inhibition assays indicate an apparent dissociation constant (K_d ) corresponding to 4 x 10^-9 M and an affinity constant (K _a) to 2.5 x 10⁸ M^-1 to K562 erythroleukemia cells. Scatchard plot demonstrated a linear slope as a manifestation of monoclonality and a low number of AML-19 specific epitopes, estimated to 1500 per cell.