Questions and Answers
What is the main purpose of the immune system?
What is the critical function of B cell receptors?
What is unique about each B cell?
How are B cell receptors and antibodies generated?
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What is the main challenge in understanding the immune system's function?
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What would happen if the immune system fails to distinguish between self and non-self cells?
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What is the significance of the B cell receptor's binding to foreign substances?
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Why is it important for the immune system to not attack the body's own cells?
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What happens to B cells that recognize self-molecules in the bone marrow?
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Why is it possible for B cells to react to the body's own proteins?
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Why doesn't a B cell die when it interacts with a bacteria it's meant to fight?
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What would happen if an antibody binds to all the insulin in the blood?
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Why is it important to eliminate B cells that react to self?
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What is the purpose of the weeding out of B cells that react to self proteins in the bone marrow?
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What happens to T cells that react to self proteins in the thymus?
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Where do B cells get their unique antibody receptors?
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What happens to a B cell that escapes the weeding out process in the bone marrow and reacts to a self protein?
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How does the body figure out which B cells react to self?
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Why does a B cell need a T cell to activate it?
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What happens to B cells that bind to self-proteins in the bone marrow?
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Why is it equally applicable to talk about T cells in this context?
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Where does the interaction between the B cell and T cell usually take place?
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What is the second mechanism of defense against autoimmune responses?
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What is the purpose of vetting B cells in the bone marrow?
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What is the result if both a B cell and a T cell that react to self proteins escape their respective weeding out processes?
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What would happen if a B cell receptor binds to a self-protein in the bone marrow?
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Why is it not possible to completely prevent the creation of B cells that react to self?
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What might happen if bacteria get into the bone marrow?
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What happens to B cells when they bind to something at this stage?
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Why is it not a major problem if bacteria get into the bone marrow?
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What happens to the B cells that react to the bacterium and are already in the lymph nodes?
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What is autoimmune disease?
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What is the result of the autoimmune disease myasthenia gravis?
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Why do antibodies against the receptor on the muscle fiber cause problems?
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What is the role of the receptor on the muscle fiber?
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What would happen if antibodies bind to the receptor on the muscle fiber?
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What is the name of the autoimmune disease where antibodies bind to the receptor on the muscle fiber?
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Study Notes
The Immune System and Self vs Non-Self
- The immune system's purpose is to fight foreign substances like bacteria and viruses, but it needs to distinguish between self and non-self to avoid attacking the body itself.
- The question of how the immune system knows not to attack itself is not obvious, and the answer lies in how B cells and T cells are generated and controlled.
B Cells and Antibodies
- B cells have unique B cell receptors that bind to foreign substances, which later become antibodies that help remove them from the body.
- Each B cell has a different receptor, generated at random through DNA shuffling, which means some might react to the body's own proteins and cells.
- This random generation process puts the body at risk of creating B cells and antibodies that react to self, which could lead to autoimmune diseases.
Preventing Self-Attack
- The body has mechanisms to prevent B cells that react to self from being activated:
- In the bone marrow, where B cells mature, the body keeps a selection of its own proteins to test the B cells' receptors. If a B cell binds to one of these proteins, it is killed.
- This process weeds out B cells that react to self, ensuring that only those that react to non-self proteins and cells are activated.
- The same process occurs for T cells, which mature in the thymus and are also tested for self-reactivity.
Second Mechanism of Defense
- Even if a B cell that reacts to self escapes the bone marrow, it usually needs a T cell that also reacts to self to activate it.
- This second mechanism of defense ensures that most autoimmune reactions are prevented, as both a B cell and a T cell need to escape their respective weeding-out processes to trigger an immune response.
What Can Go Wrong
- If bacteria infect the bone marrow, B cells that react to the bacteria might be killed, making it harder for the body to fight the infection.
- Autoimmune diseases can still occur when the body's mechanisms fail, leading to the immune system attacking the body's own cells and tissues.
- An example of autoimmune disease is myasthenia gravis, where antibodies attack the receptors on muscle fibers, preventing muscle activation and leading to muscle weakness.
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Description
The process of B cell recognition and elimination of self-molecules in the bone marrow, ensuring immune tolerance. Learn how B cells are vetted and proceed to lymph nodes to become active.