intro to immunology

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Questions and Answers

What is the primary role of β-defensins and cathelicidins in the immune system?

To facilitate organ transplantation

To promote the adaptive immune response

To inhibit cytokine production

To act as antimicrobial agents (correct)

Which of the following is NOT a component of innate immunity?

Stomach acid

Lysozyme

Antibodies (correct)

Skin barriers

Which intracellular pathogens are mentioned as part of the immune challenges?

Viruses, intracellular bacteria, and intracellular parasites (correct)

Fungi, helminths, and viruses

Viruses, prions, and extracellular fungi

Bacteria, fungi, and parasites

What type of therapy involves the use of cytokines in immunology?

Blocking cytokine therapy Signup and view all the answers

What is a primary function of physical barriers in the immune system?

Preventing pathogen entry Signup and view all the answers

What is an example of a chemical barrier in the immune system?

Stomach acid Signup and view all the answers

What is the purpose of allergen desensitization in immunology?

To reduce sensitivity to specific allergens Signup and view all the answers

Which of the following reflects a challenge posed by microbes in relation to the immune system?

Microbes can evade the immune system Signup and view all the answers

What role do antimicrobial peptides (defensins) play in immune response?

They disrupt the cell membranes of bacteria and some viruses. Signup and view all the answers

What is the primary characteristic of innate immunity?

It provides immediate defense against infections. Signup and view all the answers

Which type of cell is primarily responsible for phagocytosis?

Neutrophils Signup and view all the answers

What does opsonization refer to in the immune response?

The binding of antibodies or complement proteins to pathogens. Signup and view all the answers

Which component is recognized by innate immune receptors?

Lipopolysaccharide (LPS) of gram-negative bacteria Signup and view all the answers

What is the function of macrophages within the immune system?

They patrol tissues and engulf pathogens. Signup and view all the answers

Phagocytosis involves forming which structure to contain ingested materials?

Vesicle Signup and view all the answers

Which type of immune response is stimulated by exposure to specific pathogens?

Adaptive response Signup and view all the answers

What is the primary function of granulocytes?

To engulf and destroy pathogens Signup and view all the answers

Which innate immune cell is most abundant in peripheral blood?

Neutrophil Signup and view all the answers

What triggers the activation of Natural Killer (NK) cells?

Loss of MHC class I molecules from unhealthy cells Signup and view all the answers

Which type of white blood cell is classified as an agranulocyte?

Monocyte Signup and view all the answers

How do eosinophils primarily function against parasites?

Through enzymes that attack the cell wall of parasites Signup and view all the answers

What role do mast cells play in the immune system?

Defend against parasites and mediate allergic responses Signup and view all the answers

Which statement about basophils is accurate?

They contain inflammatory mediators to defend against parasites. Signup and view all the answers

What activates Natural Killer cells through antibody-dependent cell cytotoxicity (ADCC)?

Engagement of CD16 with antibodies Signup and view all the answers

Study Notes

Role of Immune System

The immune system functions to protect from disease.
Immune system is made up of tissues, organs, cells, molecules, and genes.
Immunology is a clinically important and evolving discipline.
Therapeutic approaches target the immune system.

Immunology in Medicine

Vaccines, antibodies, and cytokine therapy are all therapeutic approaches that target the immune system.
Organ transplantation requires immune suppression.
Allergen desensitization and adoptive cell therapy are also immunotherapies.

Microbes and Immune System

Microbes are common in nature and have evolved to infect hosts and evade the immune system.
Intracellular pathogens can include viruses, bacteria, and parasites.

The Challenges - Microbes

Microbes exploit opportunities to infect hosts.
Intracellular pathogens hijack cellular machinery to replicate and spread.
Microbes are diverse and rapidly evolve to overcome host defenses.

The Defences - Physical and Chemical Barriers

Physical barriers include skin, mucous membranes, and epithelial cells.
Skin is a protective barrier that protects the underlying tissues.
Mucous membranes trap pathogens and prevent them from invading the body.
Cilia in the respiratory system move mucus and trapped pathogens.

Chemical Barriers - Antimicrobial Agents

Chemical barriers include:
- Stomach acid
- Antimicrobial peptides (defensins)
- Lysozyme
- Digestive enzymes
Antimicrobial peptides (defensins) disrupt the cell membranes of bacteria, fungi and viruses.

Immune Responses

The immune system has two main types of responses: innate and adaptive.
Innate immunity is immediate and provides a first line of defense.
Adaptive immunity is specific to pathogens and requires exposure to activate.

Cells of the Immune System

The immune system contains a multitude of different types of white blood cells (leukocytes).
Leukocytes include neutrophils, macrophages, T cells, B cells, and others.

Innate Immunity

Macrophages are phagocytes that patrol tissues.
Macrophages are found throughout the body and there are numerous subsets with tissue-specific names (e.g., Kupffer cells in the liver).
Neutrophils are the most abundant type of white blood cell in the blood.
Monocytes are another type of agranulocyte present in the blood.

Phagocytosis

Phagocytosis is the process of engulfment and internalization of particulate matter (e.g., pathogens).
Phagocytosis forms a vesicle (phagosome) that contains the ingested material.
Phagocytosis is an important mechanism to eliminate pathogens, cell debris, and damaged tissue.
Opsonization is the coating of microbes with proteins (e.g., antibodies or complement) that facilitate phagocytosis.

Innate Immune Cell Summary - Phagocytes

Phagocytosis is the primary function of:
- Macrophages
- Granulocytes (neutrophils, eosinophils, and basophils)
Immature dendritic cells primary function is to activate the adaptive immune system.

Innate Cells - Neutrophils

Neutrophils are granulocytes with multilobed nuclei.
Neutrophils are typically not found in tissues but can be recruited to the site of infection.
Neutrophils have a short lifespan after activation.

Innate Cells - Eosinophils

Eosinophils are granulocytes found in low numbers in the blood.
Eosinophils contain enzymes that attack the cell walls of parasites.
kill antibody-coated parasites.
role in allergic diseases.

Innate Cells - Basophils

Basophils are granulocytes found in low numbers in the blood.
Basophil granules contain potent inflammatory mediators that are important in the defense against parasites.
allergic responses.

Innate Cells - Mast Cells

Mast cells are granulocytes found in tissues.
Mast cells, similar to basophils, contain potent inflammatory mediators and are involved in allergic responses.
release of granules containing histamine and active agents.

Innate Cells - Natural Killer Cells

Natural Killer (NK) cells are lymphocytes.
NK cells kill host cells infected with viruses or cancer cells.
NK cells produce chemical mediators called cytokines.

NK Cells Activation

NK cells are activated by:
- Antibodies
- NKG2D ligands
- Loss of MHC Class I molecules
Antibody-dependent cell cytotoxicity (ADCC) is a process where NK cells kill antibody-coated cells via CD16.
MHC Class 1 is a protein present on all nucleated cells that interacts with inhibitory receptors (KIR) on NK cells.
MHC Class I is downregulated in viral infection and cancer cells.

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Description

Explore the critical role of the immune system in protecting against diseases and its various therapeutic approaches in medicine. This quiz also delves into the interaction between microbes and host defenses, highlighting challenges posed by intracellular pathogens. Test your knowledge of immunology and its importance in health and disease.