Percentage of neutrophils with CD64 expression (nCD64%) was significantly higher in patients with SAH and infection than in those without infection and controls [76.2% (56.9–86.5) vs. 16% (12.6–23.1) vs. 7.05% (1.4–9.5), p < 0.05], as was their mean fluorescence intensity [MFI; 1431 (229–1828) vs. 853 (20–968) vs. 99.5 (54.7–140.7), p < 0.05]. Here, FCGR1A is linked to infection.