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Immunology > T Cells, HIV > Flashcards

T Cells, HIV Flashcards

1
Q

Ratio of T cell in lymphocyte population

A

Two-third of circulating lymphocytes

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2
Q

Origin and Maturation of T cells

A

Origin: Bone marrow

Maturation: Thymus gland

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3
Q

Origin and maturation:

T cells VS B cells

A

B cells are manufactured and matured in bone marrow

T cells are manufactured in bone marrow BUT maturation takes place in thymus gland

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4
Q

Process of maturation of T cells

A
  • Auto-reactive cells are removed
  • Then they develop into either T helper cells OR cytotoxic T cells
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5
Q

Which class of HLA is recognised by helper T cell and cytotoxic T cell?

A
  • Cytotoxic T cell recognises class-I HLA
  • T-helper cell recognises class-II HLA
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6
Q

Which clusters of surface antigen (= CD: Clusters of Differentiation) are expressed by T cells?

A

All T cells express CD3

  • CD4 is conserved among helper-T cells (CD4+ helper-T cells)
  • CD8 is conserved smong cytotoxic T cells (CD8+ cytotoxic T cells)
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7
Q

Can we distinguish T cells under light microscopy?

A

NO

All T cells look much the same under light microscopy

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8
Q

Investigation to distinguish T cells

A

Flow cytometry

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9
Q

How do we distinguish T cells by flow cytometry?

A

We identify clusters of surface antigen ( = Clusters of differentiation = CD)

All T cells express CD3

Only T helper cells express CD4

Only cytotoxic T cells express CD8

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10
Q

Which CD (Clusters of differentiation) is “Common” to be expressed by CD4+ helper-T cells and CD8+ cytotoxic T cells?

A

CD3

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11
Q

T-helper cells: Common subtypes

A
  • Th1
  • Th2
  • Th17
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12
Q

The most aggressive phenotype of T-helper cell

A

Th-1

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13
Q

The most tolerant phenotype of T-helper cell

A

Th-2

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14
Q

Which type of T helper cell has a prominent inflammatory response?

A

Th-1

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15
Q

What can trigger type-1 T-helper cells (Th-1)?

A

Cytokines (such as IFN: Interferon)

>>> resulting in a hostile environment for pathogens

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16
Q

What can trigger type-2 T-helper cells (Th-2)?

A

Cytokines, such as: Interleukin-10 (IL-10)

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17
Q

Th-2: Functions

A
  • Associated with “humoral response”
  • Drives antibody class switching
18
Q

Give an example when Th-2 predominates

A

Pregnancy

19
Q

Predominant subtype of T-helper cells in Pregnancy

A

Th-2

20
Q

Recent sub-type of T-helper cell

A

Th-17 (T-helper cell type 17)

21
Q

What does activate Th-17?

A

IL-17

22
Q

Which type of T cells are current subject of pharmaceutical trials across a borad range of diseases?

A

Th-17 (along with its activator IL-17)

23
Q

Cell that provides immune system a “window” into other cells

A

T lymphocytes

24
Q

Cell that is especially imporant defence against intracellular pathogen

A

T cells

25
Q

Association of T cells with autoimmunity

A

Normal function of T cell is essential to prevent autoimmunity

26
Q

What is genetic predictor of autoimmune disease & example?

A

Genetic predictor is the genetic code for HLA on chromosome 6

Example:

  • HLA-DR4 >>> Rheumatoid Arthritis
  • HLA-Cw6 >>> Psoriasis
27
Q

Name a T-cell deficiency disease

A

HIV AIDS

28
Q

Main effect of HIV on T cells

A

HIV causes progressive depletion of CD4 T-helper cell population

29
Q

Which type of T cell is affected/depleted by HIV?

A

CD4 T cells

30
Q

How does HIV deplete CD4 T cells?

A
  • IL-2 (a cytokine) is central to T cell proliferation
  • HIV supresses IL-2 >>> induced T-cell deficiency state
31
Q

Which type of cytokine is supressed by HIV?

A

IL-2 (interleukin-2)

32
Q

Similarity of “mechanism” between “HIV infection” and “Ciclosporin or Tacrolimus drugs”

A

Both inhibit IL-2

33
Q

Similarity of “side-effects” between “HIV infection” and “Ciclosporin or Tacrolimus drugs”

A

Both cause same pattern of opportunistic infection (as both inhibit IL-2)

  • TB (Tuberculosis)
  • Pneumocystis Jerovecii
  • Disseminated viral disease
34
Q

“Opportunistic infections” that are common between “HIV infection” and “Ciclosporin or Tacrolimus drugs therapy”

A
  • TB (Tuberculosis)
  • Pneumocystis Jerovecii
  • Disseminated viral disease
35
Q

Number of ‘specific’ receptor on lymphocytes (B cell or T cells)

A

Each individual lymphocyte expresses a “single type of receptor” with “unique specificity” (except dual specificity T cells)

36
Q

Type of receptor on B cell and T cell

A
  • B cell receptor >> memrane bound immunoglobulin (IgM monomer or IgD isotype) >> recognises particular Ag
  • T cell receptor >> TCR (T cell receptor) complex: a heterodimer >> recognises peptide fragments (presented by MHC molecules)
37
Q

Where is the ‘antigen specificity’ of B cell and T cell generated?

A
  • For B cells >> bone marrow
  • For T cells >> Thymus
38
Q

When is the ‘antigen specificity’ of B cell and T cell generated?

A

During development (at maturation phase)

39
Q

How is the ‘antigen specificity’ of B cell and T cell generated?

A

By recombination of gene segments encoding the variable domains (antigen recognition domains) of immune receptors

  • These gene recombinations are random
  • Maturing lymphocytes that express autoreactive receptors >>> then deleted or rendered anergic
40
Q

Are all autoreactive lymphocytes deleted duting development?

A

NO

Not all autoreactive lymphocytes are deleted during development.

In the case of T lymphocytes,

  • NOT all proteins are expressed in the thymus

AND the proteins that are present only in the periphery OR at certain stages of development >>> will encounter mature T cells that can respond to them.

>>> Thus, autoreactive T cells exist in the periphery (and other mechanisms are responsible for the protection of the body against autoimmunity)

Immunology (16 decks)

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