Foundations of Medical Science: Immunology (Intro Lecture)

Question 1

7 Main concepts of Immunology

Answer 1

1) the immunne system must strike a balance between hyper and hypo reactivity
2) The immune system has 2 overlapping compartments, the innate immune system and the adaptive immune system
3) the antigenic specificity of the adaptive immune system is due to the presence of antigen specific receptors
4) antigen receptors have tremendous diversity that is generated through a DNA rearrangement process called VDJ recombination
5) Specific adaptive immune responses are activated and expanded through a process known as clonal selection
6) The adaptive immune system has memory
7) The immune system is tightly regulated

Question 2

The immune system bust strike a balance between

Answer 2

hypo and hyper reactivity

Question 3

Hyporeactivity

Answer 3

states associated with clinical immunodeficiency:

congenital or acquired immunodefieiency

Immune senescense (old age)

Immunosuppression resulting from treatment (latrogenic)

Malnutrition or metabolic imbalances

Malignancies or infectious diseases

Trauma or stress

Question 4

Example: acquired immunodeficiency

Answer 4

HIV infection leads to depletion of CCD4+ T cells, which play a key role in the adaptive immune response

HIV pts are succeptable to infection that is rarely seen in normal population

EX: Kaposi’s sarcoma is a rare dz that traditionally mainly affects elder medeterrainian men

1980s started to be seen in HIV pop

In 1994 it was dicovered that human herpes virus 8 (KSHV) was the cause of these lesions

Question 5

Immune hyperreactivity

Answer 5

States associated with clinical hyperreactivity

Systemic autoimmunity

Organ specific autoimmunity

allergies and asthma

immunopathology (ususally caused by infection)

Question 6

The immune system has two overlapping compartments:

Answer 6

The innate and adaptive immune systems

Question 7

Innate immunity

Answer 7

provides early line of defense against microbial infection

consists of non-specific effectors

Question 8

Acquired immunity

Answer 8

occurs as a response to infection

consists of specific responses to microbial antigens

Question 9

Innate immunity cells

Answer 9

epithelial barriers

phagocytes

complement

NK cells

Question 10

adaptive immunity cells

Answer 10

B lymphocytes

T lymphocytes

antibodies

effector cells

Question 11

Innate immune system info

Answer 11

Most primative type of immune system, found in virtually all multicellular animals

innate immune elements are always present and active, and are constituatively expressed (some components can be up-regulated) thus, this is the first line of defense agains infection

Nonspecific; not specifically directed against any particular infectious agent or tumor

the magnitude and kinetics of an innate response are the same every time; unlike the adaptive immune system there are no memory responses

Question 12

Components of the innate immune system

Answer 12

Physical barriers (skin)

Protective secretions ( mucous, pH, antimicrobial peptides or lipids)

phagocytic cells (macrophages and neutrophils)

Enzymes (ie digestive enzymes)

Components of the complement system (which recognize common antigens foiund on microbes)

Cytokines, soluable factors taht promote defensive responses and also help to shape the adaptive response

Question 13

Adaptive immune system info

Answer 13

found only in vertebrates

must be induces

usually highly specific to antigens derived from microbes. These antigens can be proteins, carbohydrates, lipids, ect. Different arms of the adaptive immune system can respond to the different types of antigens (Note autoimmunity is due to adaptive immunity against self antigens)

The adaptive immune system has memory- there is an increased reactivity upon subsequent exposure to a pathogen

the adaptive immune system is usually able to distinguish between self and nonself

Question 14

Components of the adaptive immune system

Answer 14

antigen presenting cells (dendritic cells, macrophages, ect), components of the innate response which prime adaptive immune responses

B lymphocytes, which produce antibodies

T lymphocytes, which help other lymphocytes (such as B cells and macrophages) respond to antigen (t helper cells) or can bind to and kill infectef cells (cytotoxic T cells)

Cytokines, soluable factors secreted by all of the above cells that can aid in controlling the adaptive immune response

Question 15

The antigenic specificity of the adaptive immune system is due to

Answer 15

the presence of antigen specific receptors

Question 16

Answer 16

B lymphocyte

Immunoglobulin molecule (b cell receptor)

Question 17

Answer 17

T lymphocyte

T cell receptor

Question 18

Answer 18

B lymphocytes bind to antigen and then secrete antibodies for that antigen

Question 19

Answer 19

T lymphocytes bind to poptide presented by an antigen presenting cells

Question 20

Antigen receptors have tremendous diversity that is generated through DNA rearrangement called

Answer 20

VDJ recombination

Mix and match

allows us to recognise lots of things without devoting a lot of DNA to it

Question 21

VDJ recombination

Answer 21

the genome encodes a large, but limited number of gene segments

random selection and joining of gene segments from this pool results in tens of millions of different receptor sequences

This provess contributes to antibody diversity and also to the diversity of T cell receptors

Question 22

What concept underlies the effectiveness of vaccines?

Answer 22

the adaptive immune system has memory

Question 23

The immune system is tightly regulated

Answer 23

The adaptive ikmmune system has developed mechanisms to eliminate or inhibit self reactive B and T cells

These mechanisms are collectively known as immunological tolerance

Question 24

Central tolerance

Answer 24

Elimination of potentially self-reactive cells during their development

Question 25

Peripheral tolerance

Answer 25

A veriety of different mechanisms that prevent the activation of potentially self-reactive cells that escape centeral tolderance