active immunity
immune response that is specific to a particular pathogen and arises after an immunizing event
adaptive immunity
immune response that is specific to a particular pathogen and arises after an immunizing event, such as vaccination or an infection
antibody
type of protein that can be secreted from or bound to the surface of B cells and recognize antigens
antigen
a specific portion of a foreign particle that activates an immune response
antigen binding site
a constant domain and the variable region that binds to a target antigen
antitoxin
antibody that can neutralize a specific toxin
B cell
adaptive immune cell that reaches maturation in the bone marrow
cell-mediated immunity
immune reaction that utilizes the ability of T cells to kill other cells without the involvement of antibodies
class switch recombination
capacity to change a specific part of each antibody molecule to replace the mu chain that forms the IgM antibody with a delta (D), alpha (A), gamma (G), or epsilon (E) chain to form each other antibody type
clonal selection
process that kills autoreactive immune cells, those that can induce an immune response against a person's own body and organs
cytokine
one of a family of chemical messengers that regulate several different immune functions
hapten
small molecule that can induce an immune response when it is attached to a larger carrier molecule
humoral immunity
immune response mediated by antibodies circulating throughout the body
immune memory
ability to deliver long-lasting, protective immunity against a pathogen
immune tolerance
state of unresponsiveness to something that should elicit an immune response
immunocompetence
ability of a person to have a normal immune response when challenged by a pathogen
immunocompromised
condition of immune system that is suppressed or inactive
killer T cell
T cell capable of destroying other cells
major histocompatibility complex (MHC)
set of proteins that presents antigens on the surface of cells to support recognition by antigen receptors
major histocompatibility complex I (MHC I)
set of proteins found on all nucleated cell types that are derived from intracellular proteins and present antigens on the cell’s surface, which are recognized by CD8+ T cells
major histocompatibility complex II (MHC II)
set of proteins only found on antigen-presenting cells, such as dendritic cells, macrophages, and B cells, and is used by these cells to present antigens picked up from extracellular sources, such as other dying cells or proteins secreted from other cells, which are recognized by CD4+ T cells
naive B cells and T cells
B cells and T cells that are mature, but have not yet been exposed to an antigen and can not generate an immune response
opsonization
coating the surface of an antigen with opsonins to enhance the interaction between phagocytic cells and the antigen
passive immunity
immunity that results from the transfer of antibodies from one person to another
secondary response
immune response that occurs any time a pathogen is encountered subsequent to an initial infection that prompted the development of memory cells against the pathogen’s antigen
specificity
ability of an adaptive immune cell to recognize a particular target antigen
T cell
adaptive immune cell that is generated in the bone marrow and matures in the thymus
T cell clone
a T cell in a population of effector T cells that are specific to a particular antigen
vaccine
nonpathogenic substance that is used to generate a protective immune response against a particular disease
variable region
part of the B cell antigen receptor protein that determines what antigen it can bind