Targeting Talk: Not the Right Stuff

Are all lots of 192-Saporin (192-IgG-SAP, Cat. #IT-01) the same?

There are variances from lot to lot, and Advanced Targeting Systems includes a cytotoxicity graph on the data sheet with each product comparing the current lot with previous lots. Chemicon International also sells immunotoxins, and used to distribute ATS products. However, since early 2002 (according to Chemicon) they have been outsourcing their 192-Saporin from an un-named laboratory. A lot obtained from Chemicon was tested under ATS quality control conditions (see graph at right) and was found to be significantly less active than any of the ATS lots.

How do I find out the optimal dosage?

For each new lot and each new application of immunotoxin, it is recommended that the end user perform preliminary tests to ascertain the proper dosage. The material used and the method of administration are important aspects of each experiment that should be carefully considered prior to beginning a full-blown project.

What happens if I use too much immunotoxin?

Customers who had used the Chemicon material and then ordered 192-Saporin from ATS have reported that they needed to reduce the dosage level with ATS product. The Chemicon material was not as potent. Higher doses of 192-Saporin, (as described in Leanza et al. Eur J Neurosci, 1995, 329-343) cause deficits in hindlimb coordination and support, and ataxia. So it is important to use less if you’ve switched from Chemicon’s material to the ATS 192-Saporin.

C6/9 cells were plated at 2500 cells/well in a 96-well plate and incubated overnight. 192-Saporin was added in 10-microliter volumes and the plates were incubated for 72 hrs. The plates were developed with PMS/MTS for 1-2 hrs, then read at 492 nm in a plate reader. Data analysis was done by PRISM (GraphPad, San Diego).

See also: Targeted Toxin Catalog