CD19 and infection: CD16+ and CD56+ are involved in antitumor and anti-infection immune responses; CD19+ is associated with hyperactive liquid immunity, and an increase in CD19+ and a decrease in CD16+CD56+ levels indicates an increase in hyperactive liquid immunity, an abnormal expression of the body's immunity, a weakened antitumor and anti-infection immune response, and severe damage to the body [13, 14].