Flashcards in Lecture 15 - Differentiation and Functions of CD8+ T cells Deck (98)
The activation of B cells is initiated by what?
Specific recognition of Ags by the surface BCRs
What stimulates the proliferation and differentiation of specific B cell clone?
Ags and other stimuli, including T helper cells
Progeny of the B cell clone may differentiate into what?
1. Plasma cells that produce IgM or
2. Other Ig isotypes e.g IgG
3. May undergo affinity maturation
4. May persist as memory cells
Mature Ag-responsive B cells develop from what?
Bone marrow precursors in the absence of Ag
Humoral immune responses are initiated by what?
The recognition of Ags by specific BCR on B lymphocytes
On naive B cells, Ag binds to what?
IgM and IgD and activates these cells
The activation of B cells results in what?
Their proliferation, leading to clonal expansion, followed by differentiation, culminating in the generation of Ab-secreting plasma cells and memory B cells
A single B cells may give rise to how may cells per week?
5000 Ab-secreting cells
At the peak of humoral immune response, about how many Abs molecules are produced every day?
Some activated B cells begin to produce Abs other than IgM and IgD. This process is called what?
Heavy chain isotype (class) switching
As humoral immune response develops, activated B cells that produce Abs that bind to Ags with increasing affinity progressively do what?
Dominate the response, a process called affinity maturation
What determines the humoral immune response?
The type and amount of Abs
Humoral immune response can be what?
Either primary or secondary
Responses are divided on what?
T-dependent and T-independent
Ab responses to protein Ags require participation of what?
Of CD4+ Helper T lymphocytes
Therefore, proteins are classified as T-Dependent Ags
A specialized type of helper T cell facilitates the formation of germinal centers. What type of T cell is it?
Follicular helper T cells
What are germinal centers?
Structures generated in secondary lymphoid organs where several steps of T-dependent humoral immune responses occur
In T-dependent responses, activated B cells differentiate into what?
Ab-secreting plasma cells
Plasma cells migrate from GCs in the peripheral lymphoid organs to where?
The bone marrow where they may live for many years
The long-lived plasma B cells do what?
Continuously secrete Abs that provide immediate protection
Ab responses to multivalent non-protein Ags with repeating epitopes, such as polysaccharides, some lipids, and nucleic acids, do not require what?
Ag-specific helper T cells
Multivalent Ags are called what?
T-independent responses are elicited by what?
Engagement of BCR and may be potentiated by the signals froom other receptors on the B cells
B cells activated by protein Ags may differentiate into what?
Memory B cells survive in a resting state without secreting Abs for many years, but they mount rapid responses on what?
Subsequent encounters with the Ags
Isotype switching and affinity maturation are typically seen in what?
Humoral immune responses to protein Ags
T cell-dependent signals drive what?
Isotype switching and affinity maturation
Primary and secondary Ab responses to protein Ags differ in what?
Qualitatively and quantitatively
In primary immune responses, What happens to naive B cells?
Stimulated by Ag, become activated, and differentiate into Ab-secreting cells that produce Abs specific for the eliciting Ag