Give two reasons why it is difficult to eradicate TB by vaccination.

How are phagocytes attracted to a site of infection?

How does the immune system detect invading pathogens?

Name three natural defenses of the body to pathogens.

What type of white blood cells carry out phagocytosis of bacteria?

How may bacteria resist phagocytosis?

What four roles do activated T cells have?

What four things must a microorganism do to be considered a pathogen?

What happens after a T-helper cell binds to an antigen-presenting cell?

What happens after the formation of a phagosome?

What is an antigen?

What is an antibody?

What is an infection?

What is formed when the cell membrane of a phagocyte fuses around a bacterium?

What is perforin and how does it kill infected cells?

What is the first step in humoral immunity?

What is the role of antibodies in immunity?

What is the role of memory cells in immunity?

What is the role of plasma cells in immunity?

What two types of cell do B cells differentiate into?

Where do B lymphocytes develop?

Where do T lymphocytes develop?