Human acute lymphoblastic leukaemia cells make human pregnancy hormone hCG and expose it on the membrane: a case for using recombinant antibody against hCG for selective delivery of drugs and/or radiations

Abstract

The binding of a humanized chimeric (cPiPP) recombinant antibody (human IgG₁, kappa linked to mouse variable regions) of high affinity (Ka 3×10¹⁰ M⁻¹) and high specificity for human chorionic gonadotrophin (hCG) with MOLT-4 cells, an acute lymphoblastic leukaemia cell line derived from a patient in relapse, has been studied. The antibody binds on the membranes of the viable tumour cells as seen by flow cytometry. Biologically active pure hCG competes with the binding. No binding is seen with an irrelevant antibody directed against an epitope on androgen independent prostate cancer cell line (DU145). Studies on permeabilized cells show that these cells synthesize both alpha and beta-hCG. Peripheral blood mononuclear cells of healthy individuals do not bind with cPiPP. The potential of this antibody for imaging and selective delivery of radiations and/or drugs to tumour cells is suggested.