Monoclonal anti-human T cell antibody and PAP-s conjugate —Preparation and selective cytotoxic properties on leukemic cell

Summary

Pokeweed antiviral protein (PAP-s) was prepared from seeds of Phytolacca americana. Monoclonal antibody against human pan-T lymphocyte Wu71 was linked to PAP-s by a disulfide bond. The results of SDS-PAGE, double immunodiffusion of active monoclonal antibody and PAP-s showed that the conjugate was highly cytotoxic to the human T-leukemic cell line CEM, but not to antigen-negative cell line SP₂/O. At a concentration of 10⁻⁹mol/L, 76.4 % of the target cells were killed, as compared with 10.1 % 10⁻⁹mol/L of free PAP-s. Treatment of the CEM cells with conjugate at 10⁻⁹mol/L reduced their rate of protein synthesis by 72.4 %, as determined with¹⁴C-leucine incorporation. The immunotoxin may be useful for the in-vitro eradication of leukemic cells in autologous bone marrow transplantation to leukemia patients.