13. A mouse is immunized with the tetanus toxoid protein (inactivated toxin) in
ID: 273682 • Letter: 1
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13. A mouse is immunized with the tetanus toxoid protein (inactivated toxin) in adjuvant. One week later, the entire population of splenic B cells are isolated from the mouse and mixed with tetanus toxoid-specific CD4 TH cells plus the purified tetanus toxoid protein. Four days later, the total number of B cells in the culture and the number of tetanus toxoid- specific B cells are determined and compared to the starting population on the day of isolation. The results are shown below. ecific B cells 10 104 103 day day day day The tetanus-specific B cells preferentially survive and proliferate because: A. They are the only B cells that express CD40. B. They are the only B cells that express the receptor for IL-21. C. They are the only B cells that proliferate in response to their antigen. D. They are the only B cells presenting the tetanus peptide to the TH cells. E. They are the only B cells that received a TLR stimulus during priming.Explanation / Answer
E. They are the only B-cells that received a TLR stimulus while priming.
For the specific antibody producing B -cells to get activated and proliferate (clonal selection) they interact with their specific antigen which is presented to them by the T-helper cells. The other B-cells which donot posses antibodies specific to the antigen donot proliferate.
Not a. because CD40 is a costimulating membrane protein found on all antigen presenting cells.
Not b. IL21 receptors are present on all T, B and NK cells.
Not c. All B-cells for which their specific antigens are present will get activated.
Not d. Antigen peptide is presented by the T-helper cells not by the B-cells
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