A NOVEL STRATEGY FOR THE NEGATIVE SELECTION IN MOUSE EMBRYONIC STEM-CELLS OPERATED WITH IMMUNOTOXIN-MEDIATED CELL TARGETING

Immunotoxoin-mediated cell targeting (IMCT)isa technique for condition ally ablating specific cell types based on the cytotoxic activity of a recombinant immunotoxin anti-Tac (Fv)-PE40. To examine the feasibilit y of this technique for the negative selection in mouse embryonic stem (ES) cells, we investigated the responsiveness of cells expressing hu man interleukin-2 receptor alpha subunit to anti-Tac(Fv)-PE40. The imm unotoxin treatment efficiently eliminated only ES cells bearing the re ceptor as a consequence of the target specificity of anti-Tac(Fv)-PE40 , indicating that IMCT can be used as a novel strategy for positive an d negative selection to enrich ES cell clones with a targeted mutation .