Lecture 2: Cells and Tissues of the Adaptive Immune System Flashcards
T cells mature under the influence of the thymus and, on stimulation by Ag, give rise to what?
cellular immunity
B cells mature mainly in the bone marrow and give rise to?
humoral immunity
What is humoral adaptive immunity mediated by?
Mediated by Abs in the blood and mucosal secretions which are produced by B cells.
What is humoral adaptive immunity the principal defense against?
Against Extracellular Microbes and their toxins because secreted Abs can bind to these microbes and toxins and assist in their elimination.
What is CMI controlled by?
Responses of T cells which often function in concert with Ag-presenting cells and phagocytes to eliminate microbes.
What is the main function of CMI?
The killing of infected cells to eliminate reservoirs of infection.
True or False:
Helper T cells also help B cells make effective Abs thus contributing to eradication of extracellular microbes.
True
In CMI, what do T helper cells do?
- activate macrophages (IFN-gamma) to kill phagocytized microbes.
- activate cytotoxic T lymphocytes to directly destroy infected cells.
Which T helper cell activates macrophages?
Th1
Which T helper cell is involved in inflammation?
Th17
Which T helper cell is involved in activation (proliferation and differentiation) of T and B cells?
Th2
What do regulatory T cells do?
Suppress and prevent immune responses (e.g., to self antigens).
What do cytotoxic T cells do?
recognize Ags on infected cells and kill these cells
What do B cells do?
recognize soluble Ags and develop into Ab-secreting cells
What do T helper cells do?
recognize Ags on the surfaces of Ag-presenting cells and secrete cytokines, which stimulate different mechanisms of immunity and inflammation
What is the functional significance of specificity in adaptive immunity?
Ensures that the immune response to a microbe (or nonmicrobial Ags) is selective to that microbe (or Ag).
What is the functional significance of diversity in adaptive immunity?
Enables the immune system to respond to a large variety of Ags.
What is the functional significance of memory in adaptive immunity?
Increases the ability to combat repeat infections by the same microbe.
What is the functional significance of clonal expansion in adaptive immunity?
Increases the number of Ag-specificlymphocytes to keep pace with microbes.
What is the functional significance of specialization in adaptive immunity?
Generates responses that are optimal for defense against different types of microbes.
What is the functional significance of contraction and homeostasis in adaptive immunity?
Allows the immune system to recover from one response so that it can effectively respond to newly encountered Ags.
What is the functional significance of nonreactivity to self in adaptive immunity?
Prevents injury to the host during responses to foreign Ags.
What is the clonal selection hypothesis?
According to this hypothesis, Ag-specific clones of lymphocytes develop before and independent of exposure to Ag.
List the order of immunologic memory?
> an immune response eliminates the microbes that initiated the response.
> the expanded lymphocyte clones die in a contraction phase and homeostasis is restored.
> a few activated lymphocytes become Ag-specific memory cells which may survive for years after the infection.
