please answer ALL parts or questions 1, 2, 3, and 4!! Thank you very much!! Immu
ID: 151327 • Letter: P
Question
please answer ALL parts or questions 1, 2, 3, and 4!! Thank you very much!!
Immune Basics II& Pathology Question Set 1. Outline the sequence of events leading to the activation of a naïve T-helper cell Th) and subsequent differentiation into T-helper-1 (Th1) and into T-helper-2 (Th2) cells after first exposure to an antigen. (That is as far as you need to go! See Questions 2 & 3) That is, outline how Th cells interact with an APC (i.e. macrophage) and then become 'aware' of an antigen in the body, then prepare to interact with Humoral & Cellular immune responses. Be sure to include receptor types, CD type, and cytokines involved. 2. Outline the sequence of events leading to the production of circulating antibodies subsequent to activation of a Th2-cell after first exposure to an antigen (i.e. what you outlined in Question 1). That is, after a Th2-cell is activated, how does it interact with the Humoral branch of the immune system to produce a humoral immune response? 3. Outline the sequence of events leading to the activation of cytotoxic T-cells subsequent to activation of a Th1-cell after first exposure to an antigen (i.e. what you outlined in Question 1). That is, after a Th1- cell is activated, how does it interact with the Cellular branch of the immune system to produce a cellularly-based immune response? 4. A) What is T-independent antigen? B) What antibody is involved with recognizing T-independent antigen? C) What kind of configuration are are T-independent antigens, and what is the typical source of T- independent antigen? D) What is 'class-switching' of antibodies?Explanation / Answer
1: Macrophages carry out phagocytosis of viruses and present the viral protein fragments to the naive helper T cells via class II MHC molecules. This activates the naive helper T cells. Naive Helper T cells are the precursor to the three types of helper cells: TH1, TH2 and TH17. Differentiation of naive helper T cell in to one of these kind depends on the presence of the type of growth and differentiation factors. Presence of interleukin 12 in the environment makes the naive helper T cell ti differentiation into the TH1 cells. Presence of interleukin 4 in the environment makes the naive T helper cell to differentiate into the TH2 cells. Interleukins (IL) are the cytokines of the T lymphocytes and macrophages. These are the number of polypeptides secreted by these cells to serve as autocrine regulators.
2: TH2 cells are the T helper cells which are activated and produce IL-4, IL-5, IL-6 , IL-10 and IL-13. IL-4 serve to stimulate the proliferation of activated B cells and promote the production of IgE antibodies as well as increase the activity of cytotoxic killer cells. IL-5 induces activation of cytotoxic killer cells and differentiation of eosinophils. IL-6 serve to stimulate the proliferation and activation of T and B lymphocytes. So the activated TH2 cells serve in stimulation of B lymphocytes to recruit the humoral immunity against the pathogen. Eosinophills clear the infection while IgE production causes allergic responses.
3: TH1 cells are the type of the T helper cells that produce interleukin-2, IFN-gamma and TNF-alpha. Interleukin-2 serve to induce the proliferation of activated T lymphocytes and also make the macrophages to produce nitric oxide to promote the cellular immune responses. IL-2 also regulate priliferation of cytotoxic T cells which differentiate into activated effector cells. These activated cells attack and stimulate the programmed cell death of the viral infected cells.
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