该CD19 Polyclonal Antibody. CD19 is a B cell–specific molecule that controls B cell activation by complexing with the BCR. CD19 is a member of the Ig superfamily and is the dominant component for the signaling complex on B cells that includes CD21,CD81,and CD22.Humans with CD19 deficiency have reduced proliferative responses to BCR stimulation in vitro and mount impaired Ab responses to vaccination.