Figure 42.11 Which of the following statements about T cells is false?
- Helper T cells release cytokines while cytotoxic T cells kill the infected cell.
Introduction:
Majority of the lymphocytes circulating in the blood are made up of the cells called the T lymphocytes involved in the cell-mediated immune response. The types of T cells include the helper T cells, natural killer T cells, cytotoxic T cells, memory T cells, suppressor T cells, and gamma delta T cells.
Answer to Problem 1VCQ
Incorrect answer:
The incorrect answer is option (c) MHC II is a receptor found on most body cells, while MHC I is a receptor found on immune cells only.
Explanation of Solution
Explanation/justification for the incorrect answer:
Option (c) MHC II is a receptor found on most body cells, while MHC I is a receptor found on immune cells only. Major histocompatibility class (MHC) I molecules are the proteins present on the surfaces of all the nucleated cells displaying fragments of proteins from the infectious agents to the T cells. The Major histocompatibility class (MHC) II moleculesare found mainly on the cells containing antigens and on the lymphocytes and they trigger an immune response by interacting with the helper T cells. So, the incorrect answer is option (c).
Explanation for the incorrect answer:
Option (a) Helper T cells release cytokines while cytotoxic T cells kill the infected cell. Helper T cells are activated by the presence of the peptide antigens presented by the MHC molecules, rapidly divide and secrete proteins called cytokines assisting in the immune response. The cytotoxic T cells destroy the tumor cells and the virus-infected cells. So, this is a correct option.
Option (b) Helper T cells are CD4+, while cytotoxic T cells are CD8+. The T helper cells are also called the CD4+ T cells as they express the CD4 glycoprotein on their surface and the cytotoxic T cells are also called the CD8+ T cells as they express the CD8 glycoprotein at their surface. So, this is a correct option.
Option (d) The T cell receptor is found on both CD4+ and CD8+ T cells. The T cell receptor is found on both the helper T cells or the CD4+ and the cytotoxic T cells or the CD8+ T cells. So, this is a correct option.
Thus, MHC I cells are present on all the nucleated cells of the body and MHC II cells are present only on the immune cells. Hence, the incorrect answer is option (c)MHC II is a receptor found on most body cells, while MHC I is a receptor found on immune cells only.
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