Targeting Talk: Lethal Dose of Saporin in Mice

What is the LD50 of saporin in mice? Do you have references for this?

Thank you for your question. It is very helpful to have this information to calculate the appropriate dose for systemic administration.

According to the work of Thorpe et al. (J Natl Cancer Inst. 75(1):151-159, 1985), saporin alone has an acute LD50, when delivered intravenously, of 6.8 mg/kg in mice. Histologic examination of kidneys from mice receiving near-lethal doses of saporin revealed necrosis of the convoluted tubules. Other major organs had only minor changes.

Once saporin is attached to an immunoglobulin, the LD50 drops dramatically to 1.0 mg/kg in systemic administration. Near-lethal doses of the conjugates, by contrast to saporin alone, inflicted major damage to the liver and spleen of the mice while the kidneys (and other organs) appeared normal under histologic examination.