MK presentation of endogenous CD61 antigens induces CD8⁺ T-cell activation in an ITP murine model. Platelet counts were performed in the different SCID recipients in the ITP model and, on day 14, showed a significantly lower count in the platelet-immune groups (CD19-dep [dep] and nondepleted [ND]) and in MK-immune CD19-dep group (A). At that time point, CD8⁺ CD3⁺ T cells were quantified in the bone marrow of the recipient group (B). One-way ANOVA with a Tukey correction for multiple testing; n = 5; mean with SD (A-B). The correlation between CD8⁺ CD3⁺ T-cell percentage in the bone marrow and platelet count was assessed in both MK-immune (C) and platelet-immune groups (D). Pearson correlation; n = 9 (C). Spearman correlation; n = 10 (D). ****P < .0001; ***P < .001; **P < .01; *P < .05; each n corresponds to a different recipient SCID mouse.