Stim1^−/− mice are protected from antiplatelet IgG-induced thrombocytopenia and anaphylaxis. (A) Wild-type or Stim1^−/− chimeras received 7 μg JON3 (rat IgG1) or JON1 (rat IgG2b; both directed against GPIIb/IIIa) or vehicle IV and platelet counts were monitored. The results shown are mean (± SD) of 6 mice per group. (B) Wild-type or Stim1^−/− chimeras received vehicle or 100 μg JON3 orJON1 and body temperature was monitored with a rectal probe. The results shown are mean (± SD) of 5 mice per group (***P < .001).