Although Casp8ΔE385/ΔE385 mice developed slight splenomegaly and CD8+ T cell lymphopenia in the spleen, Casp8ΔE385/ΔE385Ripk3−/− and Casp8ΔE385/ΔE385Mlkl−/− mice developed more severe splenomegaly and showed a dramatically decreased percentage of B cells (CD19+) and T cells (CD3+) as well as an increased percentage of myeloid-derived cells (CD11b+) in the spleen and bone marrow (Fig. 5A, and S4A, B). The gene discussed is CD19; the disease is lymphopenia.