on the B- cell arm under antigenic stimulus what is the first thing that happens?
B-lymphocytes become transformed into antibody-secreting plasma cells.
on the T-cell arm under antigenic stimulus what is the main thing that happens?
PreT-lymphocytes differentiate into several classes of effector T cells
T cells are responsible for what?
Mediate of the B-cell response to antigen Recognize and destroy cells bearing foreign Ags on their surface Produce a variety of diffusible immunoregulatory cytokines and/or lymphokines that direct or augment the B and T cell immune responses
Cytokines and lymphokines are made out of?
proteins, glycoproteins or peptides
Cytokines and lymphokines have the means of?
intercellular communication and are secreted by a cell to stimulate the activity of another cell.
Antibody-mediated immunity (AMI) is?
an Adaptive immunity mediated by soluble globular host proteins called antibodies or immunoglobulins.
Antibody-mediated immunity (AMI) is also called?
circulating immunity or humoral immunity.
Primary immune response begins...
when an antigen penetrates epithelial surfaces, then when the antigen comes in contact with other macrophages or antigen presenting cells.
Antigens are internalized by
endocytosis by a phagocytic cell
in the primary immune response, after a antigen is eaten by a phagocytic cell then what happens?
it is "processed" by the phagocyte which becomes and antigen-presenting cell or APC.
what does the antigen-presenting cell do in the primary immune response?
it presents information about the AG to immunocompetent TH2 lymphocytes
after the APC presents its antigen information what else happens?
the TH2 (CD4+) cell recognizes the antigen together with the Class II MHC molecules, then secretes the various lymphokines that activate the B cells to become antibody-secreting plasma cells and memory B cells.
The components of the MHC II molecules are synthesized where?
in the endoplasmic reticulum of the phagocyte
the phagolysosome is also the
TH2 cells are activated to?
assist B cells make antibody.
Bacteria reside and replicate where in the host?
TH2 cells produce lymphokines which stimulate B cells to do what?
divide and differentiate into plasma cells which make antibody (Ab) against that particular antigen on the surface of the APC
are plasma cells short lived?
what produces plasma cells?
the division and clone maturation of B cells
which type of cells are long lived? plasma cells or memory B cells
memory B cells
name the 5 classes of antibodies
IgM IgG IgA IgD IgE
IgG, IgE, IgD are found as
antibody found as a dimer
antibody found a pentamer
held together by the J-chain
Dimers and pentamers
First to appear during the course of an infection and the first immunoglobulin to by synthesized by infants
appears on the surfaces of mature B cells as a transmembranous monomer where it functions as an antigen receptor
IgM bound to a microbial surface act as
IgM antibodies are mainly confined to where
these antibodies Neutralizes toxins
which antibody makes up 75% of the total serum antibody.
most common Ig found in extravascular spaces
this antibody provides passive immunity to the fetus and infant for the first 6 months of life
this antibody is effective at the neutralization of bacterial exotoxins and viruses
15% of the total antibody serum
Exists as a dimer in secretions via a J-chain
Secretion of dimeric IgA is mediated by a glycoprotein called
the secretory component.
what are the two subclasses of IgA and what are they based on?
IgA1 and IgA2 and they are based on heavy chains
which subclass of IgA is produced in bone marrow and makes up most of the serum IgA?
synthesized in GALT to be secreted onto the mucosal surfaces.
IgA1 and IgA2
has a short half life in serum (6 days), and it is lost in secretory products.
Secretory IgA is predominate where?
gastrointestinal fluids nasal secretions saliva tears other mucous secretions of the body.
secretory IgA is Important in resistance to infection of
the mucosal surfaces of the body, particularly the respiratory, intestinal and urogenital tracts.
This antibody does not activate complement
transferred in milk, via the colostrum, from a nursing mother to an infant.
provides passive immunity to many pathogens
monomeric four-chain polypeptide structure that is similar to IgG
IgD and IgE
found for the most part on the surfaces of B lymphocytes
two antibody thought to function as mutually-interacting antigen receptors for control of B-cell activation and suppression.
IgD and IgM
similar to IgG but the heavy chain (ε) is distinct.
similar to IgG but its heavy chain (δ) is unique.
0.002% of the total serum immunoglobulins
produced especially by plasma cells below the respiratory and intestinal epithelia.
binds avidly to circulating blood basophils and mast cells in the submucosal sites and the skin
initiate the pathogenesis of immediate hypersensitivity
IgE trigger the release of low-molecular weight vasoactive compounds
histamine leukotrienes platelet-activating factor certain proinflammatory cytokines such as TNF-α and IL-5
next line of defense If an infectious agent succeeds in penetrating the IgA barrier
the MALT (mucosa-associated lymphoid tissues)
why is MALT important?
because they amplify the local inflammatory response that facilitates rejection of a pathogen.
Antibody-mediated immunity response defends host against pathogenic microbes by
Opsonization Steric hindrance Toxin Neutralization Agglutination and Precipitation Activation of Complement Antibody-dependent cell cytotoxicity (ADCC)
functions of antibodies are
antigen binding and Effector function of Antibodies (Ab)
Each antibody binds to a specific antigenic determinant (epitope), This is a function of the Fab portion of the molecule, Valence of an antibody (Ab) = # epitopes Ab molecule can bind (2 or more)
Effector function of antibodies
Complement fixation (Fc region of Ab molecule), Binding to various cell types, activating them to perform some function: Macrophages, Monocytes, PMNs. and opsonization by lymphocytes