Caspase-7 deficiency protects against LPS-induced splenocyte apoptosis and lethality. (A,B) Wild-type (WT) and caspase-7^−/− mice (Casp7^−/−; both n = 4) were injected intraperitoneally with 20 mg kg⁻¹ LPS for 24 hours before spleens were collected and sections were stained with H&E (A) or TUNEL (B). (C) The number of TUNEL-positive cells in 5 high-power fields (hpf, ×400) from the white pulp of the spleen of each animal was quantified. Results represent mean plus or minus SD for each genotype. Data were analyzed by the Student t test. (D) Wild-type and caspase-7^−/− mice (n = 2) were either sham-operated or injected intraperitoneally with 20 mg kg⁻¹ LPS for 24 hours before spleens were collected and extracts were probed with an antibody against active caspase-7 (listed as Casp7; p19 denotes the large catalytic subunit) and Grb2. (E) Spleen extracts of wild-type mice that were either sham-operated or injected intraperitoneally with 20 mg kg⁻¹ LPS for 24 hours were probed with an antibody against caspase-1 (p45, procaspase-1; p20, large catalytic subunit) and active caspase-3 (p19 and p17 denote the large catalytic subunit). (F) Caspase-7^−/− (Casp7^−/−; n = 9) and wild-type mice (WT; n = 8) were injected intraperitoneally with 20 mg kg⁻¹ LPS, and their survival was monitored. Data were analyzed with the Kaplan-Meier test. Results are representative of 5 independent experiments. (G) Wild-type (WT; n = 8), caspase-1^−/− (Casp1^−/−; n = 8), caspase-3^−/− (Casp3^−/−; n = 6), and caspase-7^−/− (Casp7^−/−; n = 9) mice were injected intraperitoneally with 30 mg kg⁻¹ LPS and their survival was monitored. Data were compared with wild-type mice and analyzed with the Kaplan-Meier test. Results are representative of 2 independent experiments.