Module 1 Introduction of Immunology

Question 1

What are commensal organisms?

Answer 1

1. They enhance human nutrients absorption; aid in digestion, and provide vitamins, B&K
2. Protect against the disease and prevent colonization by other pathogens.

Question 2

Problems with oral antibiotics?

Answer 2

Treatment also kills commensal bacteria & pathogens take over

Question 3

What are pathogens?

Answer 3

Pathogens are infectious organisms that cause disease

Question 4

What kind of pathogens are there?

Answer 4

Viruses; bacteria; fungi; parasites

Bacteria are classified as either gram-positive or gram-negative according to whether they stain purple or pink using the Gram stain procedure

Question 5

Epithelium

Answer 5

General name for the layers of a cell that lines the outer surface and inner cavities of the body; protected by a tough impenetrable outer barrier

Question 6

What are complements?

Answer 6

A system of soluble plasma proteins that commands the effector cells by tagging pathogens with molecule flag

Complement proteins can also kill, pathogens without assistance from effector cells by perturbing the integrity of the pathogen membrane

Question 7

Two steps of the innate immune response?

Answer 7

1. Recognize that a pathogen is present.
2. Recruits effector mechanisms that kill or eliminate pathogens.

The overall innate immune responses is to induce a state of inflammation

Today the terms inflammation and innate immunity are used interchangeably

Question 8

What are cytokines?

Answer 8

Small messenger proteins can induce inflammation & they are hormone like

Question 9

Endothelium?

Answer 9

The thin layer of specialized epithelium, that lines the interior of a blood vessel

Question 10

What is the clonal selection and clonal expansion?

Answer 10

The processes that select pathogen specific lymphocytes for proliferation and differentiation

Question 11

Differences between innate immunity and adaptive immunity?

Answer 11

Innate immunity:
Rapid response within hours
Fixed
Limited number of specificities
Constant during the course of response

Adaptive immunity:
Slow response in days to weeks
Variable
Numerous highly selective specificities
Improved in the course of response, and I

Question 12

What are memory cells?

Answer 12

Some of the lymphocytes that contributed it to a successful adaptive immune response persist in the body, and are selected it to provide a long-term immunological memory of the pathogen, these lymphocytes are memory cells

Memory cells enable subsequent encounters with the same pathogen to elicit is stronger and faster adaptive immune response; ones that terminate infection before there are any significant symptoms

Question 13

What is acquired immunity?

Answer 13

The adaptive immunity based on immunological memory is called acquired immunity

Question 14

What is a primary immune response and a secondary immune response?

Answer 14

The first time that a person makes an adaptive immune response to a pathogen is called a primary immune response

During the primary response, the person that acquired immunological memory

Secondary immune response: faster and stronger response, when encountering the same pathogen the second time due to immunological memory

Question 15

The myeloid and lymphoid cell linage

Answer 15

See pic

Question 15

Is hematopoietic stem cell self renewing?

Answer 15

Yes they are. SO “One for you and One for Me”
Hematopoietic stem cells divide to give daughter cells that are also hematopoietic stem cells in the process of self renewal

Question 16

What are the characteristics of macrophages?

Answer 16

1. Tissue resident.
2. First to react in an infection
3. Recruit neutrophils by secreting cytokines.
4. Orchestrate local response to an infection.

Question 17

What are neutrophils

Answer 17

Short-lived infantry of innate immunity; they form pus

Question 18

Monocytes

Answer 18

They typically circulate in the blood;
Recruited by tissue resident macrophages to infection site and differentiate into macrophages

Question 19

Dendritic cells

Answer 19

1. Tissue resident.
2. Determines when adaptive immunity is required.
3. Carries intact and degraded pathogens to lymphoid tissues to initiate the adaptive immune response.

Question 20

What are BCR and immunoglobulin?

Answer 20

Cell surface pathogen receptors of B cells

Question 21

Plasma cells

Answer 21

Effector B cells / end stage of mature B cells

Question 22

Antibody

Answer 22

A soluble form of the BCR secreted by plasma cells

Question 23

TCR

Answer 23

T cell receptor, only expressed at cell surface receptors not soluble forms

Question 24

Effector lymphocytes of innate and adaptive immunity

Answer 24

See pic

Question 25

What is an epitope?

Answer 25

The part of the outer surface of an antigenic macromolecule that interacts directly with an antibody or B cell receptor is called the Epitope

Question 26

Are there differences in antigens recognized by B cells and T cells?

Answer 26

The antigens are recognized by antibodies and BCRs are more versatile and can be a whole protein, carbohydrates and lipids. Ie BCRs can recognize a molecule’s three dimensional structure

The antigens recognized by TCRs are typically short peptides of 6 to 16 amino acids and they can only be recognized if presented by MHC molecules

Question 27

MHC class I

Answer 27

Has closed groove on both ends and can only recognize max of 9 amino acids protein fragments

Can recognize the intracellular infections (all viral infections, and some bacterial infections)

Expressed by most cells

Binds CD8 T-cells

Question 28

MHC class II

Answer 28

Has open grooves on both ends and can accommodate protein fragment with up to 20 amino acids

Recognize extra cellular infections

Expressed only by professional antigen presenting cells such as macrophages, dendritic cells, and B cells

Used to active CD4 Th cells

Question 29

Primary lymphoid tissues

Answer 29

Where lymphocytes develop, and mature to the stage at which they are able to recognize and responded to a pathogen

The only primary lymphoid tissues in humans: bone marrow & thymus

B & T lymphocytes both originate from the bone marrow

B cells matures in the bone marrow

T cells matures in the thymus

Question 30

Secondary lymphoid tissues

Answer 30

Any other lymphoid tissues are secondary lymphoid tissues.

Include:
lymph nodes;
Lymphatics;
Tonsil;
Spleen;
Peyer’s patch in small intestine
MALT
GALT etc..

Question 31

Efferent lymph

Answer 31

The lymph leaving a lymph node

Question 32

Humoral immunity

Answer 32

Immunity conferred by antibodies

Question 33

Opsonization

Answer 33

Coating by antibodies or complement fragments

Opsonization alone cannot kill pathogens without the help of effector cells. Opsonization marks the pathogens for destruction and facilitates their recognition and ingestion by effector cells such as macrophages or neutrophils, which then phagocytose and kill the pathogen.

Opsonins such as antibodies or complement proteins bind to the surface of the pathogen, and the Fc receptor on the effector cell then binds to the opsonin, which facilitates phagocytosis. Once the pathogen is engulfed, the effector cell uses enzymes and other molecules to digest and destroy the pathogen.

Therefore, opsonization is an important step in the process of pathogen elimination, but it requires the help of effector cells to ultimately kill the pathogen.

Question 34

What is lymph?

Answer 34

Originated in connective tissues, and collects plasma that leaks out of the blood vessels to become the extra cellular fluid and eventually returns to the blood

Lymph is not a pumped and the flow is sluggish

Question 35

What is spleens function?

Answer 35

Spleen provides adaptive immunity to blood infections

The spleen is the organ that filters the blood to remove damaged erythrocytes

Its secondary function is that of a secondary lymphoid tissue, that defense in the body against a blood-borne pathogens

Question 36

GALT

Answer 36

Gut associated lymphoid tissue

Question 37

MALT

Answer 37

Mucosa associated lymphoid tissues

Question 38

BALT

Answer 38

Bronchial-associate lymphoid tissues