Monocyte and neutrophil activations are suppressed after incubation with healthy RBCs but not with neuraminidase-treated RBCs on their surface. The relative median fluorescence intensities (rMFIs) of CD63 (A) and CD66b (B) were measured on monocytes and neutrophils activated at baseline from the separation of whole blood samples from healthy donors (dark blue), and then coincubated with either healthy RBCs (red), anti-GPA-treated RBCs (green), healthy RBCs and indirectly with anti-GPA (purple), and neuraminidase-treated RBCs (orange). Leukocytes not separated from healthy donor whole blood (light blue) are shown as baseline (all n > 3). A one-way ANOVA test with Bonferroni post hoc was performed. ∗ P < .05; ∗∗∗∗ P < .0001.