Cooperative inhibition of AICD of control and ALPS lymphocytes by blocking cytotoxic-granule and Fas-mediated cell death. (A) The effect of the acidophilic compounds chloroquine (CHQ) and concanamycin-A (CMA) was tested on Fas- and TSST-1-induced cell death on TSST-1 T-cell blasts. Thirty minutes before the test, activated lymphocytes were incubated at 37°C with 0.1 mM CHQ or 10 nM CMA. Treated cells were then submitted to AICD or Fas-induced apoptosis as described previously. Data are means (± SEM) of duplicates from independent experiments (CT: n = 6; ALPS-I (P3): n = 3; ALPS-0 (P7 and P8) was tested once). (B) Effect of Fas/FasL blocking mAb was tested on AICD by incubating T cells with 10 μg/mL of antagonistic anti-Fas (SM1/23) and anti-FasL (2C10) mAb 30 minutes before reactivation (). These antibodies efficiently inhibit Fas-induced cell death by agonistic anti-CD95 (APO1.3) mAb (). ns indicates not significant; *P < .05; **P < .005; ***P < .001.