Table of contents

1. Introduction to Anatomy & Physiology5h 43m
2. Cell Chemistry & Cell Components12h 36m
3. Energy & Cell Processes10h 6m
4. Tissues & Histology10h 3m
5. Integumentary System2h 20m
6. Bones & Skeletal Tissue2h 16m
7. The Skeletal System2h 35m
8. Joints2h 17m
9. Muscle Tissue2h 33m
10. Muscles1h 11m
11. Nervous Tissue and Nervous System1h 35m
12. The Central Nervous System1h 6m
- Introduction to the Central Nervous System
  18m
- The Cerebrum
  48m
13. The Peripheral Nervous System1h 26m
14. The Autonomic Nervous System1h 38m
15. The Special Senses2h 41m
16. The Endocrine System2h 48m
17. The Blood3h 22m
18. The Heart3h 42m
19. The Blood Vessels3h 35m
20. The Lymphatic System3h 16m
21. The Immune System14h 37m
22. The Respiratory System3h 20m
23. The Digestive System2h 5m
24. Metabolism and Nutrition4h 0m
25. The Urinary System2h 39m
26. Fluid and Electrolyte Balance, Acid Base Balance37m
27. The Reproductive System2h 5m
28. Human Development1h 21m
29. Heredity3h 32m

21. The Immune System

Antigens

Anatomy & Physiology

21. The Immune System

Antigens

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Problem 14

Textbook Question

On which type(s) of cells are class I MHC molecules located?
a. Antigen-presenting cells only
b. B cells only
c. All nucleated body cells
d. Antigen-presenting cells and B cells

Verified step by step guidance

Step 1: Understand the role of class I MHC (Major Histocompatibility Complex) molecules. These molecules are responsible for presenting endogenous antigens (antigens originating from within the cell) to cytotoxic T cells (CD8+ T cells). This process is crucial for immune surveillance and the detection of infected or abnormal cells.

Step 2: Recall the distribution of class I MHC molecules. Class I MHC molecules are expressed on the surface of all nucleated cells in the body. This includes most body cells, as opposed to class II MHC molecules, which are restricted to antigen-presenting cells (APCs) like macrophages, dendritic cells, and B cells.

Step 3: Exclude incorrect options based on the distribution of class I MHC molecules. For example, option 'a' (Antigen-presenting cells only) and option 'b' (B cells only) are incorrect because class I MHC molecules are not limited to these cell types.

Step 4: Consider option 'c' (All nucleated body cells). This is consistent with the fact that class I MHC molecules are found on all nucleated cells, including epithelial cells, muscle cells, and immune cells, but not on non-nucleated cells like red blood cells.

Step 5: Evaluate option 'd' (Antigen-presenting cells and B cells). While APCs and B cells do express class I MHC molecules, this option is incomplete because it excludes other nucleated cells that also express class I MHC molecules. Therefore, option 'c' is the most accurate answer.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Class I MHC Molecules

Class I Major Histocompatibility Complex (MHC) molecules are proteins found on the surface of all nucleated cells in the body. They play a crucial role in the immune system by presenting endogenous antigens (from within the cell) to CD8+ cytotoxic T cells, which are essential for recognizing and eliminating infected or cancerous cells.

Nucleated Cells

Nucleated cells are cells that contain a nucleus, which houses the cell's genetic material. This includes most body cells, except for mature red blood cells and platelets. The presence of a nucleus allows these cells to express Class I MHC molecules, enabling them to present antigens to the immune system.

Antigen-Presenting Cells (APCs)

Antigen-presenting cells (APCs) are specialized immune cells, such as dendritic cells, macrophages, and B cells, that capture, process, and present antigens to T cells. While Class I MHC molecules are present on all nucleated cells, APCs also express Class II MHC molecules, which present exogenous antigens to CD4+ helper T cells, highlighting their role in initiating immune responses.

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