Elimination of murine erythroleukemic stem cells with a novel anti‐erythroid antibody conjugated to ricin a‐chain: A model for studies of bone‐marrow transplantation therapy

Abstract

We have produced a rat monoclonal antibody (MAb) MAE15 (IgG), specific for murine erythroid cells, using a murine erythroid cell line as immunogen. This MAb specifically binds to the surface of normal and neoplastic murine erythroid cells. Murine mature erythrocytes and non-erythroid cells as well as rat and human erythroid and non-erythroid cells are not recognized by MAb MAE15. Immunoblotting analysis and mixed precipitation in agar gel showed MAb MAE15 to be specific for murine epitope of 69 kDa antigen of erythroblasts (Ag-Eb), an interspecies antigenic marker of nucleated red cells and reticulocytes. A conjugate (immunotoxin) was prepared, comprising ricin A-chain and MAb MAE15. The immunotoxin inhibited protein synthesis of murine erythroleukemic Ag-Eb-positive K-2 cells and completely inhibited (at the concentration of 2 X 10(-7) M) spleen colony formation by erythroleukemic stem cells of the Ag-Eb-positive RAL cell line. Approximately 35% of the murine normal stem-cell (CFU-S) population was not affected by the immunotoxin at the concentration of 2 X 10(-7) M. This experimental system may be a convenient model for studies of bone marrow transplantation therapy of erythroleukemias.

Effect of gangliosides on binding, internalization and cytotoxic activity of ricin

“…The cytotoxic effect of ricin was determined by measuring the inhibition of ['%Jleucine incorporation into EB-3 cells caused by the toxin [12].…”

Heterogeneity of peripheral blood reticulocytes: A flow cytometric analysis with monoclonal antibody HAE9 and thiazole orange

“…In previous reports [1,2,3], an inter-species 70 kD membrane glycoprotein specific for mammalian erythroid cells, in particular, erythroblasts (Ag-Eb) was described. MAB HAE9 directed against a human epitope of Ag-Eb is reactive with 36% of late committed erythroid progenitors (CFU-E), almost 100% of proerythroblasts, erythroblasts, and normoblasts.…”

Two different anti‐erythroid monoclonal antibodies in immunodiagnosis of human leukemias: A comparative study

“…In previous reports (Ievleva et al, 1976;Tonevitsky et al, 1986;Mechetner et al, 1987) we described an inter-species 70 kDa antigen specific for mammalian nucleated erythroid cells, an antigen of erythroblasts (Ag-Eb). MAb HAE9 directed to a human epitope of Ag-Eb reacts positively with 36% of CFU-E and almost 100% of proerythroblasts, erythroblasts, normoblasts and reticulocytes.…”