CXCL8 and Alzheimer disease: Combined serum and plasma analysis found that IL1β (p = 0.001), IL6 (p = 0.010), IL8 (p = 0.046), IL18 (p = 0.007), CRP (p = 0.029), and hsCRP (p < 0.001) were significantly raised in serum and plasma in people with AD compared to HC (Table 1).