The A3 subclone was derived from a Jurkat cell line obtained from the laboratory of Gerald Crabtree at Stanford University.
The Jurkat cells were treated with Fas Antibody and isolated by limiting dilution to obtain a cell line that had a low spontaneous rate of resistance to Fas-medicated apoptosis.
The resulting wild-type A3 subclone is very sensitive to Fas-mediated apoptosis.
Wild-type A3 cells were made neomycin resistant and treated with three cycles of exposure to the frameshifting mutagen ICR-191 to isolate clones harboring recessive mutations that were resistant to killing by Fas antibody.
ICR-191 treated clones were serially diluted in 96-well plates in the presence of Fas Antibody for 3 to 5 weeks.
Two of these ICR-191 treated clones have been deposited at the ATCC. They are I 9.2 (ATCC CRL-2571)
, a clone with a mutation in the cysteine protease caspase-8/FLICE and I 2.1 (ATCC CRL-2572)
, a clone with a mutation in the adaptor FADD.