Immunology Concepts and Discoveries

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Questions and Answers

What did Elie Metchnikoff observe when he injected a foreign body into starfish larvae?

The formation of antibodies

The activation of T-cells

The multiplication of bacteria

The presence of amoeboid cells (correct)

What historical practice involved the inhalation of dry scab powder from smallpox lesions?

Vaccination

Variolation (correct)

Immunization

Antigen therapy

Who is credited with developing the smallpox vaccination?

Louis Pasteur

Edward Jenner (correct)

Emil von Behring

Elie Metchnikoff

What theory did Emil von Behring contribute to regarding immunity?

Humoral Theory Signup and view all the answers

What phenomenon is associated with the action of diphtheria antitoxins?

Phenomenon of cross-immunity Signup and view all the answers

In which era was the Cellular Theory of Immunity attributed to Elie Metchnikoff?

Late 1800s Signup and view all the answers

Emil von Behring's Side Chain Theory suggests that immunity is due to which component?

Humoral components Signup and view all the answers

What term refers to the group of proteins that enhances antibody response?

Complements Signup and view all the answers

What is the primary site for B cell maturation?

Bone marrow Signup and view all the answers

Which type of lymphoid tissue is associated with the gut?

GALT Signup and view all the answers

Which cells are primarily responsible for capturing antigens in lymphoid follicles?

Dendritic cells Signup and view all the answers

What does antigen-independent lymphopoiesis refer to?

Maturation occurs spontaneously in specific organs Signup and view all the answers

Which organ serves as the site of T cell maturation?

Thymus Signup and view all the answers

In addition to the gut, which of the following is a type of Mucosa-Associated Lymphoid Tissue (MALT)?

Bronchus Signup and view all the answers

What symptom is most likely caused by allergic reactions involving lymphoid follicles?

Swelling and itching Signup and view all the answers

What is the role of the bone marrow in the lymphoid system?

Source of B and T cell precursors Signup and view all the answers

What is the main role of haptoglobin in the immune system?

Binds hemoglobin Signup and view all the answers

Which of the following does NOT represent a type of passive immunity?

Recovery from infection Signup and view all the answers

What type of vaccine mimics natural infection?

Live, attenuated vaccines Signup and view all the answers

Which of the following is a characteristic of killed/inactivated vaccines?

Variable or poor memory responses Signup and view all the answers

What is the primary role of ceruloplasmin in the immune response?

Binding copper and oxidizing iron Signup and view all the answers

Which type of acquired immunity involves recovery from infection?

Active natural immunity Signup and view all the answers

What is true about adoptive immunity?

It uses soluble mediators to regulate immune components Signup and view all the answers

Which immunological component is primarily responsible for opsonization?

C3 Signup and view all the answers

What type of immune cells are primarily responsible for the killing of antibody-coated parasites?

Eosinophils Signup and view all the answers

Which component plays a key role in the regulation of the inflammatory response by neutralizing certain released products?

Major Basic Protein Signup and view all the answers

What is the primary function of macrophages?

Killing intracellular parasites Signup and view all the answers

Which of the following statements about monocytes is true?

They can give rise to macrophages upon migration. Signup and view all the answers

What is the expected normal range of eosinophils in blood per microliter?

0-150/µL Signup and view all the answers

What type of immune response do monocytes primarily respond to?

Chemotaxins Signup and view all the answers

Which type of cell mediates antigen presentation in tissues?

Macrophages Signup and view all the answers

What does the presence of NADPH oxidase contribute to during the immune response?

Reactive oxygen species production Signup and view all the answers

What characteristic makes unstable and inert molecules poor antigens?

They are unable to elicit an immune response. Signup and view all the answers

Which of the following best describes autoantigens?

They do not stimulate an immune response under normal circumstances. Signup and view all the answers

What is the main function of MHC Class I molecules?

Activation of cytotoxic T-cells. Signup and view all the answers

In which situation would alloantigens be important?

During blood transfusions and tissue transplantation. Signup and view all the answers

Which cells are primarily responsible for presenting MHC Class II molecules?

Dendritic cells and activated B-cells. Signup and view all the answers

What can result from a deficiency in T-regulatory cells?

Autoimmunity. Signup and view all the answers

How are cytokines related to activated Th cells?

They are essential for B-cell antibody production. Signup and view all the answers

What is a major consequence of failed immunologic tolerance?

Tissue rejection. Signup and view all the answers

Which alleles are included under HLA in MHC Class I?

HLA-A, HLA-B, and HLA-C. Signup and view all the answers

What does degradability refer to in the context of antigens?

Ability to be processed and presented with MHC molecules. Signup and view all the answers

Study Notes

Cellular Theory of Immunity

Elie Metchnikoff's theory of immunity, pioneered in the late 1800s, attributed immunity to cells, specifically phagocytes.
His research involved observing the activity of "amoeboid cells" within starfish larvae, which engulfed foreign bodies.
This discovery differed from the prevailing "humoral theory," which focused on antibodies in bodily fluids.

Variolation

An early practice of inoculation in China around 1000 AD.
Involved inhaling dry scab powder from smallpox lesions.
This method aimed to induce mild disease and potential lifelong immunity against smallpox.

Smallpox Vaccination

Edward Jenner observed that milkmaids who contracted cowpox, a milder disease, showed resistance to smallpox.
He pioneered the concept of cross-immunity; the protection against one disease through exposure to a related disease.
In 1798, Jenner demonstrated that intentional inoculation with cowpox could protect against smallpox.

Humoral Theory of Immunity

Emil von Behring's late 19th-century research focused on diphtheria antitoxins.
This led to the "humoral theory," emphasizing the role of antibodies in serum (bodily fluids) in the immune response.
von Behring's observations were later explained by the "Side Chain Theory," suggesting antibodies are premade components in cells, released to neutralize specific toxins.

Immune Cells & Their Functions

Eosinophils are found in blood, primarily involved in killing antibody-coated parasites by releasing granule contents containing substances like Major Basic Protein (MBP) and cationic proteins.
Macrophages are tissue-resident cells, highly potent phagocytes (engulfing and eliminating bacterial and parasitic threats). They also play a role in antigen presentation and secretion of cell mediators.
Dendritic Cells are strong antigen-presenting cells (APCs). They are found in major organs, mucosal tissues, and lymphoid tissues. They are particularly efficient at capturing antigens.

Lymphoid Organs

Lymphoid organs are critical for the production and maturation of immune cells.
Primary/Central Lymphoid Organs: These are where antigen-independent lymphopoiesis (cell maturation) occurs.
- Bone Marrow: The source of B and T cell precursors.
- Thymus: The site of T cell maturation and development.
Secondary/Peripheral Lymphoid Organs: They facilitate antigen-dependent immune responses.
- Lymph Nodes: Filter lymph, facilitate immune responses to pathogens entering the body.
- Spleen: Filters blood, traps blood-borne pathogens, and initiates immune responses to them.
- MALT (Mucosa-Associated Lymphoid Tissues): Include GALT (gut), BALT (bronchus), NALT (nasal), and SALT (skin), which protect mucosal surfaces.

Acquired Immunity

Active Immunity: The immune system creates its own antibodies.
- Natural: Developed following exposure to an infection.
- Artificial: Induced through vaccination.
Passive Immunity: Immunity is obtained through receiving pre-made antibodies from other sources.
- Natural: Transplacental transfer from mother to baby or through breastfeeding.
- Artificial: Injected serum globulins, antitoxins, or immune globulins (ex. RHIG, RHOGAM, HBIG).

Types of Antigens

Self Antigens: Components belonging to the host.
- Autoantigens: Typically do not cause immune responses, but autoimmunity results from a loss of tolerance to these antigens.
- Alloantigens: Found in other members of the same species (relatives), can evoke an immune response.
Foreign Antigens: Derived from non-self sources, usually evoke an immune response.

Human Leukocyte Antigens (HLA - Major Histocompatibility Complex)

HLA molecules are crucial for antigen presentation to T cells.
Class I: Expressed on all nucleated cells. Present intracellular (endogenous) antigens to CD8+ cytotoxic T cells.
Class II: Found primarily on Antigen Presenting Cells (APCs) like macrophages, dendritic cells, and B cells. Present exogenous antigens to CD4+ helper T cells.

Vaccines

Live, Attenuated Vaccines: Contain a weakened version of the pathogen, simulating natural infection. They provide stronger immune responses and longer-lasting immunity.
Killed/Inactivated/Subunit Vaccines: Use inactive or fragmented components of the pathogen. They often require adjuvants (immune response potentiators) and booster doses to induce effective immunity.

Important Immune Response Factors

Structural stability: A critical factor for antigenicity. Stable, inert molecules are more effective antigens.
Degradability: Antigens must be processed and presented with MHC molecules for effective immune responses.

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Description

This quiz focuses on key concepts in immunology, including Elie Metchnikoff's cellular theory, the practice of variolation for smallpox, and Edward Jenner's groundbreaking work on vaccination. Explore the evolution of immunity from early inoculation methods to modern immunological understanding.