An immunotoxin system intended for bone marrow purging composed of glucose oxidase and lactoperoxidase coupled to monoclonal antibody 097.

The effectiveness of an antibody-enzyme immunotoxin (eIT) was investigated on human T cells. This enzyme immunotoxin contained glucose oxidase (GO) and lactoperoxidase (LPO) chemically coupled to the pan-leukocyte-specific mouse monoclonal antibody (MoAb) 097 (097-GO and 097-LPO). Human peripheral blood mononuclear cells or tumor cells were suspended in a mixture of 097-GO and 097-LPO for 30 min, and then for 2 h with glucose and NaI. The effectiveness of this eIT system was indicated by the almost complete reduction of T cell viability, as estimated by a phytohemagglutinin induced proliferation assay (99.4% +/- 0.31 depletion, mean +/- SEM of 15 experiments). The specificity of the cytotoxicity reaction was indicated by the lack of cytotoxicity of control irrelevant MoAb conjugates to T cells (1.9% +/- 4.17 of T cell depletion, eight experiments). The growth of human bone marrow myeloid progenitors (CFU-GM) was not affected by the conjugates even by increasing 100-fold the optimal cytotoxic dose. T cells were susceptible to the conjugates in the presence of up to 90% of erythrocytes. This eIT system may thus represent a new alternative immunospecific procedure for allograft and/or autograft purging, and appears to effectively replace complement-mediated methods of T cell depletion.