Introduction to the Immune System

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Questions and Answers

What role does kynurenic acid play in relation to the NMDA receptor?

It enhances NMDA receptor activity.

It serves as a precursor to tryptophan.

It acts as an antagonist to the NMDA receptor. (correct)

It increases serotonin production in neurons.

What is associated with too much NMDA activity in the context of depression?

Decreased activity of COX-2.

Increased serotonin synthesis.

Elevated levels of kynurenic acid.

Excessive production of quinolinic acid. (correct)

What is necessary for IDO to be produced in microglia?

Increases in COX~2~ production. (correct)

Presence of PGE~2~.

Absence of inflammatory cytokines.

Increased levels of serotonin.

Which statement is true regarding the conversion of tryptophan?

Neurons do not produce IDO but take it up from microglia. Signup and view all the answers

What effect does ketamine have when administered to a non-depressed individual?

It produces symptoms similar to schizophrenia. Signup and view all the answers

What role do Helper T Cells play in the immune response?

They recruit B Cells to produce antibodies. Signup and view all the answers

Which autoimmune disease involves the production of antibodies against oligodendrocytes?

Multiple Sclerosis Signup and view all the answers

What mechanism normally prevents B Cells from producing harmful antibodies?

Apoptosis of malfunctioning B Cells Signup and view all the answers

In Paraneoplastic Syndrome, antibodies mistakenly attack which type of tissue?

Healthy self-tissue Signup and view all the answers

What psychological behavior might manifest due to sickness behavior?

Anhedonia Signup and view all the answers

What is the role of microglia in response to pro-inflammatory cytokines?

They produce IDO, affecting tryptophan metabolism. Signup and view all the answers

How do proinflammatory cytokines affect cognitive function?

They alter neuron firing patterns in various brain regions. Signup and view all the answers

What happens when both the IL-1 receptor and NMDAR receptor are bound simultaneously?

There is a change in gene transcription. Signup and view all the answers

What is a physiological response generated by the hypothalamus in response to infection?

Fever Signup and view all the answers

Which autoimmune condition results in antibodies attacking neuromuscular junctions?

Myasthenia Gravis Signup and view all the answers

Which compound is formed from tryptophan when IDO is active?

Kynurenine Signup and view all the answers

How do neurotransmitters influence immune cells in the periphery?

By binding to neurotransmitter receptors on these cells. Signup and view all the answers

Which behavior is encouraged by the immune system to conserve energy when sick?

Social withdrawal Signup and view all the answers

What type of bacteria can provoke an immune response leading to PANDAS?

Streptococcus Signup and view all the answers

What could excessive NMDA activity lead to?

Neurons being excited to death. Signup and view all the answers

What is a primary difference between immune cells and astrocytes in the brain?

Astrocytes are not true immune cells. Signup and view all the answers

Which process occurs when quinolinic acid binds to the NMDA receptor?

It activates the NMDA receptor like glutamate. Signup and view all the answers

What type of cytokines usually activate astrocytes?

Anti-inflammatory cytokines Signup and view all the answers

What is the primary role of B cells in the adaptive immune response?

To create antibodies that target specific antigens Signup and view all the answers

Which of the following cell types is primarily involved in the innate immune system?

Neutrophils Signup and view all the answers

What is a common function of dendritic cells in the immune system?

Present antigens to T cells Signup and view all the answers

Which of these statements about natural killer (NK) cells is true?

They induce apoptosis in stressed self-cells. Signup and view all the answers

What initiates the differentiation of naïve B cells into plasma cells?

Cytokine signaling from T cells Signup and view all the answers

What distinguishes MHC I molecules from MHC II molecules?

MHC I molecules present endogenous antigens, while MHC II present exogenous antigens. Signup and view all the answers

Which process involves the draining of fluid from blood vessels back into the lymphatic system?

Extravasation Signup and view all the answers

What is the function of cytokines in the immune response?

To facilitate communication between immune cells Signup and view all the answers

What defines the difference between innate and adaptive immunity?

Adaptive immunity develops over time, while innate immunity is present at birth. Signup and view all the answers

Which cell type helps in the identification of infected cells by secreting perforins?

Natural Killer Cells Signup and view all the answers

What is the role of macrophages in the immune system?

To present antigens after digesting pathogens Signup and view all the answers

How do memory B cells contribute to the immune response?

They remain in the body to recognize previously encountered antigens. Signup and view all the answers

What is the significance of hemocytoblasts in the immune system?

They are multipotential stem cells that give rise to diverse blood cells. Signup and view all the answers

What type of immune cells are known as phagocytes?

Macrophages and Neutrophils Signup and view all the answers

Study Notes

Immune System Overview

The immune system protects the body from pathogens like fungi, bacteria, viruses, and parasites.
Development of immune cells occurs during their differentiation, presenting opportunities for clinical interventions.

Cell Development in Immune System

Hematopoietic stem cells are found in yolk sac of embryos, eventually migrating to the liver.
Stem cells differentiate into two main progenitor types: Common Myeloid Progenitor and Common Lymphoid Progenitor.

Common Myeloid Progenitor

Differentiates into various blood cells:
- Megakaryocytes: Produce thrombocytes for blood clotting.
- Erythrocytes: Carry oxygen as red blood cells.
- Leukocytes: Encompass all white blood cells.
- Mast Cells: Involved in histamine release.
- Phagocytes (Myeloblasts): Serve the innate immune system's first line of defense, including neutrophils, basophils, eosinophils, monocytes, dendritic cells, and macrophages.

Common Lymphoid Progenitor

Forms natural killer (NK) cells and small lymphocytes (T and B lymphocytes).
T lymphocytes are essential for adaptive immunity, while B lymphocytes differentiate into plasma cells which produce antibodies.

Innate vs. Adaptive Immune System

Innate Immune System:
- Non-specific, rapid response against pathogens.
- Includes phagocytes that engulf and destroy pathogens, presenting antigens via cytokines.
Adaptive Immune System:
- Tailored, slower response that generates specific defenses against unique pathogens through B and T cells.

Phagocyte Functions

Macrophages: Engulf pathogens, break them down, and present antigens to other immune cells.
Neutrophils: Surround pathogens; undergo apoptosis and release pus.
Natural Killer Cells: Induce apoptosis in infected or cancerous cells through perforin.

Blood and Lymphatic System Interaction

Blood vessels transport red and white blood cells; WBCs monitor for signals indicating infection.
Lymphatic system collects interstitial fluid and returns it to the bloodstream, preventing blood vessel collapse.

Lymphoid Organs

Primary Organs: Bone marrow and thymus for lymphocyte maturation.
Secondary Organs: Tonsils, lymph nodes, spleen, and Peyer’s patches that initiate adaptive immune responses.

B and T Cells

B Cells: Mature in bone marrow; develop antibodies that are specific to antigens.
T Cells: Mature in thymus; include helper T cells (assist B cells) and killer T cells (attack infected cells).
Major Histocompatibility Complex (MHC) molecules are crucial for T cell activation, distinguishing between MHC I (on all cells, for internal antigens) and MHC II (on immune cells, for external antigens).

Autoimmune Diseases

Conditions where the immune system mistakenly attacks healthy cells, undermining typical safety mechanisms.
Examples include:
- Multiple Sclerosis: Antibodies attack myelin-producing cells.
- Paraneoplastic Syndrome: Antibodies target healthy tissue mistakenly identified as tumor cells.
- PANDAS: OCD-like behaviors triggered by strep-related antibodies.
- Myasthenia Gravis: Antibodies disrupt neuromuscular junction function.

Immune System and Behavioral Interactions

Sickness behavior includes symptoms like fatigue, lethargy, and social withdrawal, correlated with immune response.
Cytokines produced in response to infection influence neural activity, affecting mood and cognitive function.

Cytokine Interaction with CNS

Immune cells and neurons communicate bidirectionally, affecting behavior and health.
Cytokines can bind directly to receptors on neurons, altering cellular activity and mood regulation.

Immune System Mechanisms in Neuropsychiatry

Disruption in the balance of pro-inflammatory and anti-inflammatory cytokines can impact mental health.
High kynurenine levels may lead to excitotoxicity, linking to conditions like depression and schizophrenia through NMDA receptor activity modulation.

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Description

Explore the fascinating world of the immune system, the body's natural defense against various pathogens such as fungi, bacteria, viruses, and parasites. This quiz covers the development of immune cells and their vulnerabilities, offering insights into clinical interventions. Test your knowledge of how our body protects itself from potential threats.