Quantification of the immunolabelling (Table 5) in the grey matter indicated that: (i) CD68 (p = 0.026), CD64 (p = 0.002), CHI3L1 (p = 0.016), IL4R (p = 0.005) and CCR2 (p = 0.010) loads were increased in AD irrespective of systemic infection; and (ii) CD16 load was affected by both AD and systemic infection (p = 0.027) such that CD16 expression was lower in AD with systemic infection (AD+) compared to AD without systemic infection (AD-). Here, CHI3L1 is linked to Alzheimer disease.