Immune System First Line of Defense

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Questions and Answers

What is a characteristic of the innate immune response?

It involves the activation of the complement system. (correct)

It is a specific response to specific attributes of an invader.

It is a slow response that develops with exposure to various organisms.

It generates immunologic memory.

What is the primary function of lysozyme in tears and saliva?

To break down the cell wall of some bacteria. (correct)

To trap microbes.

To activate the complement system.

To generate immunologic memory.

What is the role of natural killer (NK) cells in the immune response?

To trap microbes.

To produce antibodies.

To activate the complement system.

To recognize and eliminate infected cells and tumor cells. (correct)

What is a characteristic of the adaptive immune response?

It is a specific response to specific attributes of an invader. Signup and view all the answers

What is the role of sebum on the skin?

To form a protective film that inhibits the growth of certain microbes. Signup and view all the answers

What is the role of hairs in the nose and respiratory tract?

To sweep microbes away. Signup and view all the answers

What is a characteristic of B-Lymphocytes (B-cells) and T-Lymphocytes (T-cells)?

They are the primary cells of adaptive immunity. Signup and view all the answers

What is the relationship between the innate and adaptive immune responses?

The adaptive response works with the innate response system to enhance reactivity. Signup and view all the answers

What is the primary trigger for blood transfusion reactions?

Administration of an incompatible blood type Signup and view all the answers

What is the typical manifestation of autoimmune thrombocytopenia (AITP)?

Petechiae, purpura, and mucosal bleeding Signup and view all the answers

What is the primary mechanism of Type III immune hypersensitivity?

Formation of antigen-antibody complexes and localized inflammation Signup and view all the answers

What is the Arthus reaction an example of?

Localized immune response Signup and view all the answers

What is the primary cause of serum sickness?

Production of antibodies against animal serum or drugs Signup and view all the answers

What is the typical symptom of serum sickness?

Fever, painful joints, enlarged lymph nodes, and spleen, and urticaria Signup and view all the answers

What is the primary treatment for autoimmune thrombocytopenia (AITP)?

Administration of corticosteroids and/or splenectomy Signup and view all the answers

What is the consequence of immune complexes being deposited in different areas of the body?

Inflammation and tissue destruction of surrounding structures Signup and view all the answers

What is the primary cause of anaphylaxis?

Release of mediators causing smooth muscle contraction and vascular dilation Signup and view all the answers

What is the treatment for autoimmune hemolytic anemia?

Use of corticosteroids and/or a splenectomy Signup and view all the answers

What is the result of Rh incompatibility in a subsequent pregnancy?

Hemolytic disease in the fetus Signup and view all the answers

What is the characteristic of anaphylaxis?

It is a systemic life-threatening hypersensitivity reaction Signup and view all the answers

What is the common allergen associated with anaphylaxis?

All of the above Signup and view all the answers

What is the type of hypersensitivity reaction characterized by the formation of antibodies against target antigens on cell surfaces?

Type II hypersensitivity reaction Signup and view all the answers

What is the result of hemolytic disease of the fetus due to Rh incompatibility?

Anemia, jaundice, and edema in the fetus Signup and view all the answers

What is the type of hypersensitivity reaction that involves the destruction of blood cells?

Type II hypersensitivity reaction Signup and view all the answers

What is the primary function of HLA on cell surfaces?

To distinguish between self and non-self antigens Signup and view all the answers

Which type of immunity is acquired through direct exposure to an antigen and the subsequent production of antibodies?

Active natural immunity Signup and view all the answers

What is the term for the ability to distinguish between self- and non-self antigens?

Immunologic tolerance Signup and view all the answers

Which of the following is an example of passive artificial immunity?

Injection of rabies antiserum Signup and view all the answers

What is the consequence of the immune system failing to distinguish between self- and non-self antigens?

Auto-immunity Signup and view all the answers

Which class of HLA molecules is primarily found on immune system cells?

Class II Signup and view all the answers

What is the mechanism by which the immune system eliminates T- or B-cells that fail to distinguish between self- and non-self antigens?

Apoptosis Signup and view all the answers

What is the reason for the development of autoimmune disorders in some individuals?

Failure of immunologic tolerance Signup and view all the answers

What is the main consequence of the deposition of immune complexes on the glomerular basement membrane?

Inflammation of the glomerulus Signup and view all the answers

Which of the following is NOT a characteristic of Type IV hypersensitivity?

Manifests as acute inflammation Signup and view all the answers

What is the primary antigen responsible for the formation of immune complexes in Polyarteritis nodosa?

All of the above Signup and view all the answers

What is the typical duration of symptoms in Contact Dermatitis?

Few days to weeks Signup and view all the answers

What is the primary cell type responsible for the development of chronic inflammation in Graft Rejection?

T-lymphocytes Signup and view all the answers

Which of the following is a common allergen that can cause Contact Dermatitis?

Poison ivy Signup and view all the answers

What is the primary consequence of immune complex deposition in Glomerulonephritis?

Inflammation of the glomerulus Signup and view all the answers

What is the characteristic timing of symptoms in Contact Dermatitis?

12-24 hours after exposure Signup and view all the answers

Study Notes

Innate Immune Response

Rapid, early response to microbes
Non-specific, always the same response
Involves inflammation, fever, and other mechanisms
Primarily reacts to microbes
Relies on phagocytes and antimicrobials
Includes external physical barriers like skin and mucous membranes
Easy for microbes to adapt to
Stimulates adaptive responses

First Line of Defense

Skin and mucous membranes
Sebum on skin forms a protective film that inhibits growth of certain microbes
Mucous can trap microbes which can be then expectorated or sneezed out of the body
Hairs in nose and respiratory tract trap and sweep microbes away
Tears and saliva contain lysozyme, an enzyme that breaks down cell walls of some bacteria

Second Line of Defense

Antimicrobial substances, natural killer (NK) cells, and phagocytes
Involves activation of the complement system
Antimicrobial substances include interferons, iron-binding proteins, and antimicrobial proteins

Adaptive Response

Specific response to specific attributes of an invader
Develops with exposure to various organisms and substances
Slower to kick in, develops in response to specific attributes of an invader
Works with the innate response system to enhance reactivity
Attacks microbes and antigens
Generates immunologic memory, leading to a more rapid response upon subsequent exposure

Immune Cells

Primary cells of adaptive immunity are B-lymphocytes (B-cells) and T-lymphocytes (T-cells)
Lymphocytes act as regulator cells, assisting in controlling and orchestrating the immune response
Lymphocytes can identify self from non-self through HLA (Human Leukocyte Antigens)

Acquiring Immunity

Immunity can be acquired in four ways:
Active natural immunity: develops through direct exposure to an antigen and the immune system develops antibodies
Active artificial immunity: develops when the body is purposefully introduced to an antigen and subsequently reacts by developing antibodies (e.g., vaccines)
Passive immunity: passed from a mother to fetus, to protect the infant during the first few months of life as they develop their own immune system
Passive artificial immunity: when antibodies are injected from one system to another, used to help fight a current infection if the individual has not been immunized against the specific organism

Auto-Immunity

Ability to distinguish between self- and non-self antigens is referred to as immunologic self-tolerance
Auto-immunity is the mounting of an immune response against the body's own tissues
Can occur when mechanisms fail to eliminate T- or B-cells that fail to differentiate between self- and non-self antigens

Hypersensitivity Reactions

Type I - Anaphylactic Reactions

Systemic, life-threatening hypersensitivity reaction
Characterized by itching, generalized flushing, headache, difficulty breathing, and a drop in blood pressure
Caused by smooth muscle contraction and vascular dilation as a reaction to released mediators
Common allergens are food, chemicals, insect stings, and drugs

Type II - Antibody-Mediated Hypersensitivity

Mediated by IgM or IgG, directed against target antigens on cell surfaces or in extracellular tissue
Commonly involves the formation of antibodies directed against blood cells and their destruction
Examples:
Erythroblastosis Fetalis: hemolytic disease that affects neonates, caused by Rh- mother and Rh+ fetus
Autoimmune Hemolytic Anemia: antibodies produced by a patient's own body are responsible for the hemolysis of erythrocytes
Blood Transfusion Reactions: triggered by incompatible blood type, manifests as fever, chills, and renal failure due to hemolysis of red blood cells
Autoimmune Thrombocytopenia (AITP): body produces antibodies that are directed against platelets, manifests as petechiae, purpura, and mucosal bleeding

Type III - Immune Complex Mediated Hypersensitivity

Mediated by formation of antigen-immunoglobulin complexes, complement fixation, and localized inflammation
Involves IgM and IgG antibodies
Examples:
Arthus Reaction: local response, typically performed for experimental purposes, involves the injection of a foreign substance, resulting in complex formation and localized skin reactions
Serum Sickness: systemic response, caused by animal serum or drugs, resulting in the formation of an antigen-antibody complex, which gets lodged in small vessels and causes an inflammatory reaction
Glomerulonephritis: local effects, caused by acute streptococcal infection, resulting in the formation of an immune complex, which is deposited on the glomerular basement membrane, leading to inflammation of the glomerulus
Polyarteritis Nodosa: systemic effects, characterized by inflammation and necrosis of medium-sized arteries with secondary ischemia of the tissues supplied by the affected blood vessels

Type IV - Delayed or Cell-Mediated Hypersensitivity

Mediated by specifically sensitized T-lymphocytes
Manifests as sub-acute or chronic inflammation with infiltration of the tissue by the lymphocytes and macrophages, resulting in variable degrees of necrosis
Examples:
Contact Dermatitis: acute or chronic delayed type of hypersensitive response to allergens placed on the skin surface, caused by plants, drugs, cosmetics, dyes, paints, and jewelry
Graft Rejection: caused by a delayed hypersensitivity reaction, resulting in chronic inflammation and necrosis of the graft

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Description

Learn about the early response of the immune system, including physical barriers, phagocytes, and antimicrobials. Understand how microbes can adapt and stimulate adaptive responses.