Antibodies and antigen receptors

humoral

_______ immune response's cetrcentral tenant is antibody production

cell surface immunoglobulin, endocytosis

The B cell receptor is a modified _____________________ and when adjacent B cell receptors are cross-linked by an antigen, this receptor interaction mediates __________ of the antigen

immunoglobins

____________: Glycoprotein molecules which are produced by plasma cells in response to an immunogen and which function as antibodies

antigenic determinant

Each immunoglobulin actually binds to a specific _________

antigen binding

______________ by antibodies is the primary function of antibodies and can result in protection of the host

valency,

The ________ of an antibody refers to the number of antigenic determinants that an individual antibody molecule can bind to.

2

the valency of all antibodies is at least ________ but sometimes more

secondary effector functions

We often attribute antibody binding to direct neutralization of the pathogen. However, significant biological effects are often a consequence of _______________ of antibodies.

neutralize antigens, opsonization, activate classical complement cascade

what are the three main effector functions of antibodies

overall structure, receptor ligand interactions

This is based on the ______________________ of the antibody and is mediated by ______________________

phagocytic cells, lymphocytes, platelets, mast cells, basophils

list some of the cells that have antibody receptors

structure

The overall effector function of an antibody is directly related to the _________ of the antibody

variable region, constant region

what are the two functional parts of antibody molecuels

variable region

_______________: consists of both heavy and light chains and contains the antigen binding site (Fab)

constant region

____________: consists of two heavy chains and determines the antibody's biological role (Fc).

idiotype, variable region

Each B cell clone produces antibodies with a different antigen-binding site. This is referred to as the ____________ and is found on the _________ region

idiotopes, paratopes

Within an idiotype are ______________ ; smaller specific sites that bind to the antigen epitope. Still smaller are __________, which bind to even smaller sites on the antigenic epitope

heavy chains in the constant region

the 5 isotypes of antibodies depend on what?

IgM, IgD, IgG, IgE, & IgA

what are the isotypes of antibodies? (5)

function

The specific isotype reflects the __________ of the antibody and maturation stage of a B cell.

5, 3

Immunoglobulin isotypes are fairly well preserved among species. Domestic mammals have _______ different isotypes, whereas birds and amphibians have ________ isotypes.

blood, mucosa, cutaneous

IgM and IgG are systemic and are therefore in high concentrations in _________________. IgA is found in the ___________. IgE is ___________ in distribution

IgM, isotype switch

the default antibody type is _______ but B cells can change from this to others via _________________

helper T cells

Isotype switch is directed by a _____________. This is mediated by recombination of genes encoding the heavy-chain constant region.

constant region, antigen binding region

Isotype switch involves the _________ of the antibody.

the ____________________ region is unchanged

effector (plasma cells), memory B cells

________ and ________ cells will secrete antibodies with the new switched isotypes.

uncertain, surface of naive B cells

the role of IgD antibodies is ______ and its location is ____________

enhance mucosal immunity, pro-inflammatory, antimicrobial, may step in if one Ab isotype is missing

what are some proposed functions of IgD?

blood, naive B cells

where is IgM located?

IgM

the first isotype produced in the primary immune response is _____

first responder, neutralization, multivalent binding, innate immunity

functions of IgM include (4)

valency

The efficiency in activating complement is a reflection of the ___________ of IgM

IgG, blood, extravascular fluid

______ is the most abundant isotype in mammalian serum, and is present in _____ and ____________________

neutralization, agglutination, opsonization

IgG protects against systemic infections by _________ __________ and _________

inhibits the microbe from binding to the host cell surface receptor

If an antibody binds to the microbe or toxin, it effectively_________, thus preventing entry of the microbe into the cell.

clumps pathogens together

IgG _________________, making them easier for the immune system to recognize and clear.

pathogen, antibody

during the early phases of infection, ______ concentration is higher than the _________ concentration

true

true/false: in the middle phase, the concentration of pathogens and antibodies are relatively equal

true

true/false: during late stage infection, the antibody concentration far outweights pathogens

IgG, variable, Free Fc

________ is the best opsonizing antibody. The ____________ region of the IgG antibody binds to a microbe. The _________ portion of the antibody is then recognized by a phagocytic cell that has Fc receptors on its surface. When the Fc receptor is engaged, this activates the phagocyte, the microbe is engulfed and eventually killed

2

It takes ______ IgG molecules to activate a single C1 complement complex. However, IgG has a ten-fold concentration as compared to IgM, so it is still the primary activator of complement.

IgA, microbial, toxin

______ is the predominant isotype in mucosal secretions, and prevents ____ and ______ attachment

transcytosis

IgA is transported across mucous membranes via ________________

IgE

______; is associated with allergic and parasitic responses

mast cells, eosinophil

much of the IgE response is mediated by ________ and ________

degranulates, targets parasites for eosinophil-mediated killing

When IgE bind to mast cells _____ happens,

when IgE binds to eosinophils __________________________ happens

mast cells

IgE are produced by ___________

true

true/false: once IgE binds to the mast cell, the mast cell becomes "sensitized" to the specific allergen that the IgE is targeting.

histamines, leukotrienes, others

the release of mediators from mast cells includes _____, _____ and _______ to induce an allergic response

true

true/false: Regardless of the immunoglobulin class the kinetics of the immune response is similar.

lag phase

A short period after antigen exposure where no detectable antibodies are present

logarithmic growth phase

As B cells are activated, they proliferate and differentiate into plasma cells, leading to a rapid increase in antibody levels

plateau phase

Antibody levels reach their peak, which is the maximum concentration of antibodies in the body

decline phase

Antibody levels gradually decrease as plasma cells undergo apoptosis and are cleared.

memory phase

A small population of memory B cells remains after the initial response, allowing for a faster and stronger secondary response upon re-exposure to the same antigen.