Cells of the immune system are able to respond
to the presence of invading organisms because
they recognize the
(1) antigens present on the invaders
(2) antibodies present in invading pathogens
(3) DNA pattern in the nuclei of viruses
(4) antibiotics released from microbes
Through the antigens present to the invaders the Cells of the immune system can easily able to respond and recognize. During an infection, chemical signals attract phagocytes to places where the pathogen has invaded the body.
