A disease-causing organism or virus.
Immunity resulting from the transfer of antibodies or antiserum produced by another person.
A plant or animal that lives, grows, and feeds on or within another living organism.
An individual living thing composed of one or more cells.
A part of the body that has a specific function, such as the lungs.
A white blood cell that is an abundant and important phagocyte.
A T cell that has some characteristics of NK cells. It produces large amounts of cytokines when stimulated, and is activated by fatty substances (lipids) bound to non-MHC molecules called CD1d.
A large granulecontaining lymphocyte that recognizes and kills cells lacking self antigens. These cells’ target recognition molecules are different from T cells.
Powerful chemical substances secreted by monocytes and macrophages. These molecules help direct and regulate the immune responses.
A large phagocytic white blood cell which, when entering tissue, develops into a macrophage.