Which statement reflects immunity in living things?

___________________ is an example of the first line of defense.

These immune cells capture antigens and display them to B cells.

If a stem cell no longer make the transcription factor PU.1, the stem cells cannot develop into ____________________.

Natural killer cells release this cytokine to activate macrophages.

These immune cells are early responders to viruses and release interferon.

New lymphocytes need to be check to be sure they do not recognize self in a process known as ___________________. 

These immune cells release histamine during inflammation and play a role in allergies..

These effector cells release antibodies.

This complement protein is cleaved to become activated to cleave C4 in the classical pathway of complement activation.