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immunology > basic concepts on immunology > Flashcards

basic concepts on immunology Flashcards

1
Q

Define immunity

A

Immunity is the ability to resist infection caused by an intracellular or extracellular bacteria, fungi, parasite or virus

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2
Q

Name 4 types of infections

A

Fungi, virus, bacteria, parasites, tumor cells

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3
Q 
Match the infectious agents to examples:
Myobacteria, streptococcus pneumoniae
Candida
Influenza
Trypanosoma, leishmania
A

Myobacteria, s. pneumoniae-Bacteria
Candida- fungi
Influenza- virus
Trypanosoma, leishmania- parasites

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4
Q

What are 3 main components that make up the immune system?

A

Molecules: antibodies, complement cytokines

Cells: Lymphocytes, macrophages, granulocytes

Organs/tissues: bone marrow, thymus, lymph nodes, spleen

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5
Q

What is the difference between the primary and secondary lymphoid organs ?

A

Primary lymphoid organs: bone marrow and thymus, where immune cells are produced

Secondary lymphoid organs: sites of lymphocyte activation (spleen, lymph nodes and mucosal associated lymphoid tissue eg in the gut- tonsils,appendix and Peyer’s Patches)

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6
Q

How can immune cells be classified based on development ? What are they overall known as?

A

Production in the bone marrow:
From the (HSC) self renewing hempatopoietic stem cell CD34+:
1. Common Myeloid progenitor - granulocytes

  1. Common Lymphoid progenitor - lymphocytes

Overall granulocytes and lymphocytes are known as leukocytes and are found in the blood/ tissue

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7
Q

What are examples of lymphocytes and granulocytes? (leukocytes)

A
  1. Lymphocytes : B lymphocytes, T lymphocytes, Natural Killer Cells
  2. Granuclocytes: Neutrophils, monocytes, dendritic cells, mast cells, basophils, eosinophils
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8
Q

From the (HSC) self renewing hempatopoietic stem cell CD34+, what two lines of cells do you get as a result?

A
  1. Common Myeloid progenitor - granulocytes

2. Common Lymphoid progenitor - lymphocytes

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9
Q

What are the two main types of immune sytstems?

A
  1. Natural/ innate immunity

2. Specific/ adaptive immunity

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10
Q

What are the two main classifications of specific/ adaptive immunity?

A
  1. Humoral immunity (B cells)

2. T-cell mediated immunity

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11
Q

Which cells from the hematopoietic tree make up the innate/ natural immuntiy?

A

Natural Killer Cells from the lymphoid cells

Granulocytes: mast cells, dendritic cells, monocytes, neutrophils, eosinophils, basophils

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12
Q

Which cells from the hematopoietic tree make up the specific/ adaptive immunity?

A

B and T lymphocytes

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13
Q

How do the natural/ innate immunity and specific/ acquired immunity differ when recognizing pathogens?

A

Natural/ innate immunity: Pathogen recognized by receptors encoded in the germline: Pattern Recognition Receptors (PRR)eg Gram +/-, ds DNA/RNA

acquired/specific: Pathogen recognized by receptors generated randomly ie B cell receptors (BCR) and T-cell receptors (TCR) for antigen

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14
Q

How do the natural/ innate immunity and specific/ acquired immunity differ in receptor specificity?

A

acquired/specific: receptors have very narrow specificity ie recognize a particular epitope after processing

natural/innate:receptors have broad specificity, recognize many related molecular structures called PAMPS (Pathogen Associated Molecular Patterns)

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15
Q

Do cells in the natural and specific immune systems expand after exposure to antigens?

A

Natural/innate: Not able to expand after exposure to the same antigen
Specific/acquired:Production or expansion stimulated specifically by an antigen

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16
Q

What is the response time of cells in the natural versus specific immune systems?

A

specific: slow (3-5 days) because of need for clones of responding cells to develop
natural: immediate response

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17
Q

TRUE/ FLASE

Cells of the innate immune system lead to immunological memory

A

FALSE. Only cells of the acquired immune system lead to generation of B and T memory cells hence immunological memory. This leads to fast response upon the second infection eg upon vaccination, memory cells respond

18
Q

The specific/ adaptive immune system is classified into:

A

Humoral immunity

T-cell mediated immunity

19
Q

What are the two types of T-cells?

A
  1. T helper cells - CD4 + T cells
    Help other cells mount an immune response
  2. Cytotoxic T cells - CD8+ T cells
    Killing of infected cells eg in virus elimination
20
Q

What is humoral immunity?

A

B lymphocytes produce antibodies which circulate in the serum for primary defense against extracellular pathogens eg bacteria/circulating virus

21
Q

What is T-cell mediated immunity?

A

T cells (cytotoxic) by way of direct cell to cell contact or secretion of cytokines offer primary defense against intracellular pathogens, viruses and fungi, tumor antigents, graft rejection eg by eliminating whole cells./lysis of infected cell

22
Q

How does the immune system know which kind of immune response is needed?

A

Through T helper cells and antigen presenting cell interaction. APC eg macrophage phagocytes microbe and presents antigens on the surface to CD4+ T helper cells.CD4+ T helper cells activate either B cells or cytotoxic T cells. B cells once activated become plasma cells. Cytotoxic t cells once activated become active cytotoxic t cells

23
Q

What do you call an activated B cell?

A

B cells once activated by T helper cells produce antibodies and develop into Plasma cells in response to the antigen presented on the APC

24
Q

What do you call an activated cytotoxic T-cell?

A

Active cytotoxic t cell

25
Q

Why are HIV patients not able to generate B celll immune response?

A

Because HIV kills CD4+ T cells that would activate humoral response

26
Q

Naiive T helper cells are able to differentiate into different T cells after priming. Name them

A

IL-12 to Th1 to IFN-gamma TNF, antiviral/ bacterial immunity
IL-4 to Th2 to IL-4/13 , immunity to extracellular parasites
TGF-beta to Treg to TGF-beta, regulation/tolerance
TGF-beta to Th 17 to IL-17 for inflammation/fungal immunity
TFH-BCL6 to IL21 for T cell help for B cells

27
Q

How does a T helper cell know that an immune response against infection is required?/ whether to differentiate to Th1/2/17/FH

A

Information comes from Antigen presenting cell, APC belongs ot innate immunity, Express PAMPs and DAMPs

28
Q

What are PAMPs?

A

PAMPs: Pathogen Associated Molecular Pattern Molecules, derived from microorganisms and recognized by pathogen recognition receptor bearing cells of the innate immune system as well as many epithelial cells

29
Q

What are DAMPs?

A

Damage Asssociated Molecular Pattern molecules, cell derived and initiate and perpetuate immunity in response to trauma, ischemia and tissue damage either in the absence or presence of pathogenic infection.

30
Q

What is an example of pathogen recognition receptors?

A

Toll-like receptors, found on the plasma membrane, bind to ligands eg lipoprotains, DNA from bacteria/viruses

31
Q

What are examples of toll-like receptors?

A

TLR1 and 2- bind to lipopeptides bacteria

TLR3- binds to ds RNA

32
Q

How are T helper cells activated?

A

Antigen presenting cells with PRR uptake microbes, and present antigen to naiive T helper cells .

T cell receptors of naiive T helper cells recognize pathogens presented by APC via MHC class 11 molecules.(signal 1)

Antigen Presenting Cells signal CD2B to activate T cell interaction with other cells like DCs (signal 2)-general

and further then
signal 3 is activated via CD40 , a specific Th2 polarizing signal

33
Q

What is the difference between MHC class I and II antigen presentation?

A 
MHC class I present soluble pathogens of the cytosol to cytotoxic CD8 + T cells which signal to kill the antigen presenting cells. MHC class 1 is expressed by all nucleated cells
MHC class II present engulfed pathogens by primary antigen presenting cells such as macrophages and Dcs to T helper cells to activate T helper cells.
Effect: APCs are not killed, express peptides
34
Q

How does a cytotoxic T cell know that a body cell is infected and has to be eliminated?

A

Presentation of viral antigen (soluble in the cytosol) in the form of peptides via MHC class I molecules mediated by perforin/granzymes which form pores on target cells that lead to killing of the cells with the antigen.

35
Q

What is thymic education?

A

In the thymus, T cells undergo -ve/+ve selection wherre they develop specific T cell markerrs eg T cell receptor, CD3, CD4, CD8. Supressor cells can downregulate.

36
Q

How can an immune response be regulated?

A
  1. production of the right set of cytokines ie pro inflammatory/anti inflammatory . An imbalance of Th- autoimmunity, allergy, cancer
  2. Effector/ regulatory cell balance. CD4+CD25+ Tcells,TR1. An imbalance-autoimmunity, cancer, allergy
37
Q

Regulatory cells are positive in cancer and persistent infection. True/ false?

A

True

38
Q

What could be the possible immune response against COVID019?

A

Pathogen associated Molecular pattern molecules are recognized by TLR3 specific to dsRNA on the surface of an APC. MHC class II present theengulfed antigen to Thelper cells. Naiive T helper cells get activated and signal to B cells to differentiate into plasma cells hence produce antibodies IgG AND IgM against COVID-19 virus.

39
Q

Which factors coordinate immune response?

A

Th1 (antiviral/bacterial immunity),
Th2 (extracellular parasites),
Th 17
Treg

40
Q

Which cells are responsible for the regulation of an immune response?

A

CD4+ CD25+ T cells

TR1

41
Q

Where do T cells mature?

A

In the thymus. They begin as hematopoietic precursors from the bone marrow and migrate to the thymus where they are called thymocytes

immunology (2 decks)

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