Ablation of the immune system does not rescue the macrothrombocytopenia in G6b-deficient mice. (A) Platelet counts and (B) volumes of WT, G6b KO, Rag1 KO, and G6b/Rag1 double-knockout (DKO) mice were measured, n = 10 to 26 mice per genotype. Rag1 KO mice exhibited normal platelet counts and volumes. However, deficiency of the immune response did not rescue the phenotype in G6b KO mice, as G6b/Rag1 DKO mice exhibited severe macrothrombocytopenia (A-B). (C) GPVI and (D) α2β1 platelet surface expression in WT, G6b KO, Rag1 KO, and G6b/Rag1 DKO mice was measured by flow cytometry, n = 8 to 10 mice per genotype. G6b/Rag1 DKO mice exhibited decreased GPVI and α2β1 expression, similar to those observed in G6b KO mice. ∗∗∗P < .001, 1-way ANOVA with Dunnett’s test, mean ± SEM.