ABSTRACT
The job of the immune system is to protect the body from harmful invaders. It does this by providing nonspecific barriers to invasion as well as customized defenses against specific threats. The cells that are involved in these processes are commonly known as the
white blood cells
and include
polymorphonuclear leukocytes
(PMNs),
lymphocytes
, and
monocytes
. These cells originate and mature in the bone marrow and in
lymphatic tissues
, including the
thymus
,
spleen
, and
lymph nodes
, and travel throughout the lymphatic and circulatory systems. They communicate with each other and with other cells of the body through the exchange of chemical messengers called
cytokines
. We will discuss these cells, their functions, and the potential effects of toxicants on the system as a whole.
