The following questions deal with the experiment described below: A CBA strain n
ID: 226300 • Letter: T
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The following questions deal with the experiment described below: A CBA strain neonatal mouse is thymectomized and irradiated to destroy its immune system. The mouse immune system is then reconstituted by adoptive transfer of bone marrow from another CBA mouse. Two weeks later the neonatal mouse is given T cells from a semi-allogenic donor mouse. The donor mouse is between a CBA mouse and a C57 mouse. The mouse is then injected with SRBCs as an antigen. Five days later the spleen from the mouse is removed and the spleen cells are divided into 3 groups. Group 1 spleen cells are incubated with autologous serum and complement. Group 2 spleen cells are incubated with anti-CBA complement. Group 3 are incubated with anti-C57 and complement. The spleen cells are then washed and the number of cells secreting antibody against the sheep RBCs is determined. a. What technique would be used to determine the number of cells secreting AB to the SRBCs? b. What class of antibody (IgM, IgG, IgA, IgE, or IgD) would you expect to be secreted by these cells? Why? c. What results would you expect in groups 1, group 2, and group 3 concerning the number of cells secreting Ab to the SRBCs? Explain the basis of your reasoning. d. How would you modify the previous experiment (question 4) to show that the T-helper subset of T cells was important in the subsequent development of Ab secreting cells? What technique might you use to get the T helper cells to use? Be specific in the details of your answer. Answers can be continued the back.Explanation / Answer
b. IgM is the first antibody to be secreted in response to an antigen and the spleen is the major site where these antibodies are synthesized.
Therefore, these cells will secrete IgM antibodies primarily.
c. In group 1: Greater number of cells secretes Ab to SRBCs
The spleen cells, which were activated by prior injection of SRBCs, now secretes antibodies against the plasma cells. The complement reacts with antibodies bound on SRBCs and mediates their lysis.
In group 2: No hemolysis, therefore no antibody against anti-CBA antigen.
In group 3: Hemolysis occurred because antibodies are generated against anti-B57 antigens.
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