Lecture 15 - Differentiation and Functions of CD8+ T cells Flashcards Preview

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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 Ags


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 cells


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


In secondary immune responses, what occurs with B cells?

The same Ag stimulates memory B cells, leading to the production of greater quantities of specific Abs than are produced in the primary response