MICROBIOLOGY - CHAPTER 13
Accessory receptor protein on T helper cells that binds to MHC class II molecules
CD4
T cells express with a __________ or a ________ coreceptor
CD4 CD8
Found onles cytotoxic T cells, and it binds MHC class I molecu
CD8
Mature T cells can express:
CD8 coreceptors CD4 coreceptors
______ _______________ play important roles in the immune response, serving to activate different components of immunity.
Cell Markers
Gene code for makers that appear on all nucleated cells. They display unique characteristics of self and allow for the recognition of self molecules and regulation of immune reactions.
Class I
MHC genes also code for immune regulatory makers. These makers are found on macrophages, dendritic cells, and B cells, and involved in present antigens to T cells during cooperative immune reactions.
Class II
MHC genes encode proteins involved with the complement system, among others.
Class III
Distribution in Lymphatic organs B cells
Cortex (in follicles)
Each human produces antibodies with ___ _______ different specificities
10 trillion
Large complex macromolecules approaching a molecular wight (MW) of___________ ______________ are the most immunogenic
100,000 Daltons (a unit of molecular weight)
Acquired specific immunity is the product of a dual system, they are _____ and _____ lymphocytes.
B T lymphocytes
When activated, it divides, giving rise to plasma cells, each with the same reactive profile.
B cells
All cells - both _________ cells and __________ cells have a variety of different markers on their surfaces,
foreign self
Small foreign molecules that are too small by themselves to elicit an immune response are termed
haptens
Naive B cells do what
home in on specific sites (ie. lymph nodes) and circulate through the blood
The process of eliminating any lymphocytes with receptor that recognize self molecules during the development process is
immune tolerance
Specific immunity only occurs after an ____________ event
immunizing
A molecule that stimulates a specific response by T and B cells are called a _________ or ___________
immunogen antigen
B lymphocytes, the receptor genes that undergo the recombination are genes coding for
immunoglobulin
Large glycoprotein moleules that serve as the antigen receptors of B cells and, when secreted, as antibodies.
immunoglobulin
T and B cells in the periphery of the body have mechanisms to prevent reaction with _____________ antigens
innocuous
Specific T - cell areas of circulation
lymph nodes spleen
B cells (lymohocytes) irulate through the blood, "homing" to specific sites in which areas?
lymph nodes, spleen, and gut-associated lymphoid tissue (GALT)
B cells and T cells also constantly circulate between the which areas?
lymphatic and general circulation systems
The property of memory refers to the rapid mobilization of ______________
lymphocytes
B and T cells constantly recirculate through the circulatory system and lymphatics, migrating into and out of the _________ _______
lymphoid organs
Tissue _____________ ingest the pathogen and induce an inflammatory response in the tissue if appropriate.
macrophages
Three different cells can serve as APCs,they are:
macrophages B cells dendritic
One set of genes that codes for human cell makers or receptors is the ______ _________________ _______
major histocompatibility complex (MHC)
B cells that have made it through the maturation process have not yet encountered antigens so they are called _________ B cells and they entered circulation in order to home in on specific sites
naive
PAMPs are molecules shared by many types of microbes that stimulate a _____________ response
nonspecific
Bone marrow stromal cells guide B cell development by:
nurturing lymphocyte stem cells and providing chemical signals that initiate B cell development
These glycoproteins (MHC molecules) are found on all cells except ____ ________ _______
red blood cells
The specific immune response is highly ________ which means that a given antibody, B cell receptor, or T cell receptor only recognizes a specific antigen
selective
During the generation of lymphocyte receptor diversity, any cells that develop a specificity for _________ molecules are eliminated.
self
By the time T and B cells reach the lymphoid tissues, each one is already equipped to respond to a ________ _________ ________
single unique antigen
Two features that most characterize this third line of defense are
specificity memory
These cells are found in bone marrow. This was first discovered in birds.
stromal cells
Bacterial toxins that belong to a group of immunogens are called
superantigens
B cells specific surface markers
Immunoglobulin
Each human ________ a unique combination of class I MHC genes from their parents
Inherits
PAMPs
Pathogen-associated molecular patterns
Release antibodies into the tissue and blood.
Plasma ells
Lymphocyte specificity is
Preprogammed, existing in the genetic makeup before an antigen has ever entered the system
The maturation of T cells and the development of their specific receptors are directed by the __________ _________ and its __________
thymus gland hormones
______ cells are the "mediators" of cell mediated immunity.
T
Which cell receptor is relatively small and never secreted?
T cell receptors
Receptors that bind antigens that have been processed and complexed with MHC molecule on presenting cell surface.
T cells
Secretes cytokines that help destroy pathogens and regulate immune responses.
T cells
Superantigens are potent stimuli for which cells?
T cells
Which cells do not produce antibodies
T cells
PAMPs and antigens share the following characteristics
They are parts of foreign cells They provoke an immune response
MHC Class I molecules on host cell display unique characteristics of self which is important tot he process of:
Tissue rejection
Any exposed or released protein or polysaccharide is a potential _________ for specific immunity.
antigen
Any exposed or released protein or polysaccharide is potentially an
antigen
During their developmental process, B and T lymphocytes undergo a selective process that specializes them for reacting only to one specific
antigen
The ends of the forks formed by the light and heavy chains contain pockets called
antigen binding sites
Perceived as foreign, meaning that it is not a normal constituent of the body is an
antigen or immunogen
In most immune reactions, the antigen must be further acted upon and formally present to lymphocytes by called called
antigen-presenting cells (APCs)
Highly individual and stimulate specific immunity are ___________
antigens
Mature lymphocytes eventually populate the lymphatic organs where they encounter
antigens
The _________ __________ theory is a conceptual explanation for the development of lymphocyte specificity and variety during immune system maturation.
clonal selection
The mechanism by which the exactly correct B or T cell is activated by an incoming antigen is a process called
clonal selection
Each genetically unique line of lymphocytes arising from the extensive recombination of surface proteins is termed a
clone
The entire ____________ region of an antibody has an amino acid content that does not vary greaty.
constant
Tissue ____________ cells ingest the antigen and migrate to the nearest lymphoid organ.
dendritic
Cytotoxic T cells that lead to the destruction of infected host cells and ___________ cells
foreign
It is acceptable to think of antigens as ____________ molecules that stimulate the immune response
foreign
Most materials that serve as antigens fall into these chemical categories:
*Proteins and polypeptides ( enzymes, cell surface structures, exotoxins)*lipoproteins (cell membranes) * glycoproteins (blood cell makers) * nucleoproteins (DNA complexed to proteins but not pure DNA)*polysaccharides (certain bacterial capsules) and lipopolysaharides
When comparing the T and B cell antigen-specific receptors they both:
1. Are formed by genetic rearrangements 2. Contain variable and constant regions 3 Are inserted into the lymphocyte cell membrane 4. Belong to the same protein family
The presence of Superantigens in infection activates T cells at a rate of _______ times greater than ordinary antigens.
100
____________ is a process by phagocytic cells
Antigen
Huge cells nurture the lymphocyte stem cell an provide chemical signals that initiate which cell development.
B
Receptors that bind antigens
B cells
T cell receptor for antigen belongs to the same protein family as the __ ______ receptor.
B-cell
Receptors for antigen - B cells
B-cell receptor (immunoglobulin)
Some diseases (autoimmunity) are thought to be caused by the loss of immune tolerance through the survival of
Forbidden clones
Circulation in blood - T cells
High numbers
MHC is also known as the _________ _____________ _________ (HLA) ____________
Human Leukocyte Antigen System
The ability of the body to react with countless foreign substances, develops
Immunocompetence
Circulation in blood - B cells
Low numbers
Markers that "accept" or "grasp" antigens in some form are called
Lymphocyte Receptors
MHC gene complex gives rise to a series of glycoproteins called _____ ___________
MHC Molecules
Lymphocytes arise from the same basic stem cell type, they also diverge into two distinct type
Maturation of B cells in specialized bone marrow sites. T cells occurs in the thymus.
Distribution in Lymphatic organs T cells
Paracortical sites (interior to the follicles)
Which cells produce antibodies?
Plasma cells
Memory is important to specific immunity in that it allows:
Rapid mobilization of antigen specific memory lymphocytes
Antigens or immunogens are defined as molecules that stimulate a response by which cells ______ and _____
T Cells and B Cells
T cell specific surface markers
T cell receptor several CD molecules
Specific immunity is the product of
a dual system of B and T lyphocytes
Each genetically distinct lymphocyte expresses only
a single specificity and can react to only one type antigen
The third line of immunity is not innate, it is____________
adaptive
Cell surface markers and molecules that occur in some member of the same species but not in other are called
alloantigens
A T cell gives rise to one of three different type of progeny, each involved in a ______-___________ immune function
cell-mediated
T-lymphocyte response is
cell-mediated immunity
After activation, the B or T cell multiplies rapidly in a process called
clonal expansion
T cells secrete soluble mediators called ________ that help destroy pathogens and regulate immune responses.
cytokines
When plasma cells release the antibodies, they attach to the antigen for which they are specific, the antigen is marked for____________ or _________________
destruction or neutralization
Lymphocytes capacity to discriminate differences in molecular shape is so fine that it recognizes and responds to only portion of hte antigen molecule called
epitope
The T cell antigen-specific receptor differs from the B cell antigen-receptor in that it has
fewer antigen binding sites
Antigen receptor diversity in lymphocytes is due to
genetic rearrangement events
The specificity for a single antigen molecule is programmed into the lymphocyte and is set for the life of a
given cell
immunoglobulins are large ________ __________ that serve as the antigen receptors of B cells and, when secreted, as antibodies.
glycoprotein molecules
The multiplication of a particular lymphocyte creates a clone, or a group of genetically identical cells, some of which are __________ cells
memory
When foreign cells cross the first line of defense and enter the tissue, resident _____________ migrate to the site.
phagocytes
When foreign cells or pathogens first enter a tissue, resident ____________ migrate to the site of antigen entry
phagocytes
Antigens are usually
proteins polysaccharides
During lymphocyte stem cell differentiation, random gene ______________________ occur that results in the generation of a large arry of antigen receptor diversity
rearrangement events
Lymphocytes have been programmed to "_______" their first engagement with the invader
recall
MHC genes have been identified in how many classes?
three
There are how many import features of clonal selections?
two
The __________ regions found on both the heavy and light chains in an antibody molecule come together to form the antigen binding site
variable
Extreme versatility in antigens is due to
variable regions (V)
