Cell-mediated thrombocytopenia and bleeding are specific to CD8⁺ T cell lymphocytes. (A) Platelet counts in irradiated SCID mice transferred with either 5 × 10⁴ nondepleted immune spleen cells (n = 9; □) or 5 × 10⁴ immunized spleen cells depleted of both CD8⁺ T cells and CD19⁺ B cells (n = 8; ○). (B) Kaplan-Meier survival plot of each group shown in panel A.