Chapter 9: Immunity Mediated by B Cells and Antibodies

B-cell activation requires cross-linking of the _____________ (two or more receptors)

B-cell receptor

Receptor associated _____________ phosphorylate tyrosine residues in the ITAMs of cytoplasmic tails of Igα (blue) and Igβ (orange). Syk binds to the phosphorlated ITAMs of the B-cell receptor Igβ chains.

tyrosine kinases

The B cell co-receptor is composed of _____, _____, and _____.

CR2; CD19; CD81

Phosphorylated ____ generates _____________that synergize with those generated by the B-cell receptor.

CD19; intracellular signals

T_FH cells help antigen-activated B cells through cell-surface interactions between ________________________ and by the targeted delivery of secreted cytokines to the B-cell surface.

CD40 ligand (T_FH cell and CD40 (B cell)

(MTOC) Microtubule-organizing center

Cellular structure responsible for the nucleation, stabilization, and organization of microtubules

Replication of B cells happens in the ________________. B cells start to produce ____ here as well.

medullary cord; IgM

B cells interact with T_FH cells in the _____________- where the T_FH cells release _________ for further B cell maturation.

boundary zone; cytokines

Expansion of antigen-activated B cells in the primary folicule creates the ___________________. This is where _________ and ________ occurs.

germinal center; affinity maturation; class switching

Class switching of B cells is based on ___________ release and interaction.

cytokine

A _____________ is a small, non-dividing B lymphocyte that is found in the germinal centers of secondary follicles.

centrocyte

T_FH cell cytokines _____ and _____ promote differentiation of antigen activated B cells into plasma cells (produces antibodies) or memory cells 

IL-21; IL10

As infection subsides, _____________________ under the influence of the same cytokines into long-lived memory B cells

centrocytes differentiate

____, _______ and monomeric _____ protect the internal tissues of the body

IgM; IgG, IgA

The receptor ___ transports ____ from the bloodstream into the extracellular spaces of the tissues

FcRn; IgG

IgM, IgG, and IgA bind and _________ any _____________ that enter the blood and tissues

neutralize; microorganisms

__________ IgA, and ___________ IgM protect __________________ of the body

Dimeric; pentameric; mucosal surfaces

Transcytosis

Transport of molecules from one side of the epithelium to the other. This involves endocytosis into vesicles

A _________ is made between one _______________________ of either one IgA dimer or one IgM pentamer

disulfide bond; poly-Ig receptor and the J chain

The receptor is called polymeric immunoglobulin receptor (or ____________) because _________________________

poly-Ig receptor; it specifically binds to IgA dimers or IgM pentamers

______ provides a mechanism for rapid killing of ________ and __________.

Functions as a cell-surface receptor of antigen not as a soluble antibody

IgE; parasites; pathogens

____________ contain large granules containing _______________________________________

Mast cells; histamine and inflammatory mediators

________________ that is present on the surface of____________________________________

Fc receptor called FcεRI; mast cells, basophils, and activated eosinophils

Two or more IgE/FcεRI ______________ causes _____________. Can also cause __________

crosslinked; degranulation; allergy

Before and after birth, mothers provide their children with protective _____________

antibodies

During pregnancy ___ from the maternal circulation is transported across the __________________ and delivered directly to the ______________

IgG; placenta by FcRn; fetal bloodstream

Transfer of IgG across placenta into fetal bloodstream by FcRn is so efficient that, at birth, human babies have a level of IgG in their plasma that is as ________________, and with as ______________ of antigen specificities.

high as that of their mothers; wide a range

The transfer of _________________________________________ is an example of the passive transfer of immunity

preformed IgA from mother to child in breast milk

Protein-F binds ___________

fibronectin

Disease-causing bacterial infections at mucosal surfaces are prevented by neutralizing antibodies. The antibodies________________ and _______________________ to bind to the cilia or to attach to the fibronectin in the extracellular matrix, and so they prevent the bacteria from remaining in the pharynx.

coat the bacteria; impair the capacity of protein F of the bacteria

Binding of IgM and IgG (multiple) to antigen on a pathogen’s surface activates complement by the ____________

classical pathway

Membrane attack complex (MAC)

C5-C9 (polymerization of 18 C9 molecules

At least ______________ of IgG bound to pathogens or soluble antigens are required to activate the complement cascade.

two molecules

___________________ helps to clear immune complexes from the circulation.

Erythrocyte CR1

___________________________ can be bound by cells expressing the complement receptor CR1. Most numerous of the cells expressing CR1 is the erythrocyte, or ___________, which outnumbers the leukocytes by about 500 to 1. Thus, most immune complexes become bound to the surface of erythrocytes.

Immune complexes covered with C3b; red blood cell

Erythrocytes _________________________ where tissue macrophages remove and degrade the complexes of ______________________ from the erythrocyte surface.

pass through the liver and spleen; complement, antibody, and antigen