Neutrophils and Macrophages

neutrophils are

always present in the blood plasma to engulf pathogens

how do neutrophils know which cells to engulf?

they recognize opsonins

what is an antigen?

a substance that causes the immune system to produce antibodies against it

if an antigen is foreign

the immune system responds

unlike neutrophils, macrophages have

major histocompatibility complex (MHC)

when the MHC complex moves to the outside of the macrophage wall, what is the macrophage now called?

an antigen presenting cell (APC)

what is an APC?

a cell that displays and antigen bound by an MHC on its surface

what do APCs secrete?

cytokines; proteins that signal neutrophils, macrophages, B-cells, and T-cells to come to the site

what does inflammation signal?

an immune system response; blood is flowing to the area with white blood cells

white blood cells are

leukocytes

what kind of leukocytes are B cells and T cells

lymphocytes

where are macrophages located?

in the blood and lymph nodes