Voce's Path 1st Midterm Review Flashcards
CD4+ T cells can become Th1 or Th2 cells. What is the difference between Th1 and Th2?
Th1 is effective against intracellular pathogens.
Th2 leads to B cell production against extracellular pathogens,
If a CD4+ T cell is exposed to ___, it becomes Th1. What secretes it?
IL-12, secreted by macrophages in response to when they have ingested a microbe
If a CD4+ T cell is exposed to ___, it becomes Th2.
IL-4, secreted by Th2 cells and mast cells, other tissue cells
What does IFN-y release result in? What does it inhibit?
What stimulates its secretion? Who secretes it?
Th1 cells produce the cytokine interferon-γ (IFN-γ), which activates macrophages to kill phagocytosed microbes (classical pathway of macrophage activation).
also stimulates the production of IgG, which promote the phagocytosis of microbes.
Inhibits Th2 differentiation
What is the most potent macrophage-activating cytokine known? Who secretes it?
IFN-y
Th1 cells, Natural Killer cells
When an effector T lymphocyte recognizes the antigens of ingested microbes on a macrophage, it does two things. It changes its expression of +++, and it releases +++.
In response to this recognition, the T lymphocytes express CD40L, which engages CD40 on the macrophages.
It secretes interferon-γ (IFN-γ), which binds to IFN-γ receptors on the macrophages.
This combination of signals activates the macrophages to produce microbicidal substances that kill the ingested microbes.
In addition to the potent macrophage-activating cytokine, Th1 cells also release two other important cytokines. What is the significance of these?
IL-2: T cell proliferation, as well as granuloma formation, macrophage activation etc.
Hot T-bone stEAK
IL-1: fever (hot) IL-2: stimulates T cells IL-3: stimulates bone marrow IL-4: stimulates IgE IL-5: stimulates IgA Il-6: stimulates aKute phase protein production
TNF-a: activates endothelium, causes white blood cell recruitment
When is Th2 stimulated?
in the presence of a parasitic worm, allergic response to environmental antigens
What cytokines are released as a consequence of Th2 stimulation, and what do they do?
Il-4: stimulates B cells to produce IgEs, which bind to mast cells and promote mast cell degranulation
IL-5: activation of eosinophils
IL-13: intestinal mucus secretion, preventing pathogenic breach of tissue
How do Th2 cytokines influence macrophages?
Th2 cytokines inhibit classical macrophage activation and stimulate the alternative pathway of macrophage activation.
Remember, M1 macrophages are phagocytic, proinflammatory.
M2 macrophages have anti-inflammatory effects, wound repair, fibrosis.
