However, SCD patients presented significantly lower activation of CD8+ cells after stimulation by the influenza vaccine antigens than the control group (control 1.8%(1.4–4.0); SCD 1.3%(0.9–1.9), p = 0.0073) (Fig 3) while responses to PHA (maximal stimulation) were vigorous and similar among all groups (CD4+CD69+, control 53,4%(33,5–63,1); SCD 58,0%(48,9–68,1) and CD8+CD69+, control 63,3%(56,2–71,3); SCD 72,3%(62,8–87,2)). Here, CD4 is linked to influenza.