Chapter 11

Microbiology, Immunology, And Molecular Genetics 670 with Chapes at Kansas State University

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Created: 2012-03-06
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naive B cells

have not encountered antigen - circulate in the blood and lymph and are carried to the secondary lymphoid organs, most notably the spleen and lymph nodes

affinity maturation

consequence of activation - progressive increase in the average affinity of the antibodies produced sa the response to activation proceeds.

progenitor B cell (pro-B cell)

earliest distinctive B-lineage cell

will not develop further without stromal cell environment

precursor B cells (pre-B cells)

with the help of microenvironment provided by the bone marrow stromal cells directly interacting with pro-B cells as well as secreting various cytokines (most notably IL-7) proliferate and differentiate into...

pre-B cell

on completion of heavy-chain rearrangement --> cell is classified as a

immature B cell

completion of light-chain rearrangement --> cell is classified as an

surrogate light chain

in pre-B cell, the membrane mu chain is associated w/ the ___________, a complex consisting of two proteins: a V-like sequence called Vpre-B and a C-like sequence called lambda5, which associate noncovalently to form a light-chain-like structure

E2A

B cells lacking this transcription factor do not express RAG-1, are unable to make DhJh rearrangements, and fail to express lambda5, a critical component of the surrogate light chain

pro-B stage

cells in this stage do not display the heavy or light chains of antibody, but they do express CD45R, a protein tyrosine phosphatase found on leukocytes, and the signal-transducing molecules Ig-alpha/Ig-beta

type 1 thymus-independent

most antigens for this cell type are mitogens (able to activate B cells regardless of specificity)

such as LPS and other bacterial cell wall components

Thymus independent type 2 antigens

these antigens activate B cells by extensively cross-linking the mIg receptor

they do not act as polyclonal activators

they activate only mature B cells

cytokines derived from Th cells are required

transition from G1 to S

critical restriction point in the cell cycle

activation of B cell to proceed through this requires signal 1 and signal 2

B-cell receptor (BCR)

membrane Ig is associated w/ the disulfide-linked heterodimer Ig-alpha/Ig-beta forming the

immunoreceptor tyrosine-based activation motif (ITAM)

cytoplasmic tails of both Ig-alpha and Ig-beta contain the 18-residue motif termed the ______________________________ -- which is also present in several molecules of the T-cell-receptor complex

CD19

is the key member of the B-cell coreceptor complex and has a long cytoplasmic tail that provides docking sites for molecules that augment signals delivered by the BCR complex

CR2

this component of the B-cell coreceptor is a receptor of C3d, a breakdown product of the complement system --> demonstrates different arms of the immune system working with one another

CR2

this component of the coreceptor complex binds to complement-coated antigen, this cross-links the coreceptor to the BCR and allows the CD19 component of the coreceptor to interact w/ the Ig-alpha/Ig-beta component of the BCR

immunoreceptor tyrosine inhibitory motif (ITIM)

activation of B cells results in the phosphorylation of this in the cytoplasmic tail of the inhibitory CD22

T-B conjugate

once a Th cell recognizes a processed antigenic peptide displayed by a class II MHC molecule on the membrane of a B cell, the two cells interact to form a

CD40/CD40L interation

provides an essential signal for T-cell-dependent B-cell activation

drives B cell into G1

cortex

B cell rich area in lymph nodes

paracortex

T cell rich area in lymph nodes

secondary follicles

provide a specialized microenvironment favorable for interactions b/t B cells, activated Th cells, and follicular dendritic cells

germinal center

formed when activated B cells, together w/ some activated Th cells, migrate toward the center of the secondary follicle

germinal centers

these 3 important B-cell differentiation events take place where?

affinity maturation

class switching

formation of plasma cells and memory B cells

dark zone

this well-defined area of a germinal center houses proliferating B cells known as centroblasts

centroblasts

are distinguished by their large size, expanded cytoplasm, diffuse chromatin, and absence or near absence of surface Ig

centrocytes

centroblasts eventually give rise to these

move into light zone, where some make contact w/ antigen displayed as antigen-antibody complexes on the surface of follicular dendritic cells

follicular dendritic cells

most important factor influencing selection is the ability of membrane Ig molecules on the centrocyte to recognize and bind antigen displayed by these cells

engagement of CD40 on the B cell by CD40L on the helper T cell

indispensable feature of interaction b/t developing b cell and CD4+ T cell

About this deck

By: Ben Yunk
Created: 2012-03-06
Size: 30 flashcards
Views: 2

About StudyBlue

“I have used this website for three exams, and I see a huge difference in my test results.”
Naj