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Advanced Immunology and Cell Biology > Immune deficiency > Flashcards

Immune deficiency Flashcards

1
Q

How are most PIDs inherited?

A

In an autosomal recessive manner

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2
Q

Besides inherited PIDs, what could be the reason for sporadic cases?

A

Genetic mutations such as insertions or deletions. There are also susceptible and rare genetic variants with a higher chance of mutation.

Some mutations can be acquired during the gamete phase in the parent.

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3
Q

Which PID patients have trouble controlling viral infections?

A

Patients who suffer from INF-a and INF-b deficiency

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4
Q

What immune cells do patients deficient in GATA2 lack?

A

NK-cells, monocytes, B-cells and dendritic cells.

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5
Q

What is the difference between IRF7 in humans versus mice?

A

IRF7 is thought to weaken the body’s defense against viruses.

In humans, IRF7 deficiency is not found to be detrimental to antiviral defense, but deficiency in mice causes susceptibility to several DNA and RNA viruses.

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6
Q

What is a consequence in patients deficient in IRF9?

A

They cannot form ISGF3 complexes, thus having an impaired INF response pathway.

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7
Q

What does IRF9 do?

A

IRF9 gets activated by interferon receptors after TYK2 and JAK1 kinases. It binds to STAT1 and STAT2, forming a transcription factor complex which is then used for INF-I transcription.

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8
Q

What is the function of IRF7?

A

IRF7 is a transcription factor that activates the transcription of INF-I after endosomal PRR activation by viral RNA.

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9
Q

What virus are IRF9 deficient patients susceptible to?

A

Influenza virus.

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10
Q

For which TLR gene has a PID been identified? What is this protein used for?

A

TLR3. This is a PRR that recognizes dsRNA and activates IRF3 and NF-kb in an antiviral INF-I and III response.

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11
Q

What virus are TLR3-deficient patients predisposed to?

A

HSV-1 in the central nervous system and some influenza viruses.

Overall, TLR3 shows redundancy, with exception of those two viruses.

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12
Q

What are Type I interferonopathies?

A

Autoinflammatory diseases characterised by upregulation of INF-I

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13
Q

What is the definition of Immunodeficiencies?

A

Disorders of the immune system that manifest with increased susceptibility to infection.

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14
Q

What is the difference between primary and secondary immunodeficiencies?

A

Primary ones are inborn or caused by a genetic mutation

Secondary ones are acquired deficiencies. Patients are born with a normal immune system

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15
Q

What could be reasons for secondary immunodeficiencies?

A

HIV, malnutrition, chemotherapy, diseases which affect the immune system (diabetes, leukemia)

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16
Q

What makes PIDs heterogenous?

A

PIDs can be caused by a vast array of genetic mutations, all different in nature

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16
Q

What makes PIDs heterogenous?

A

PIDs can be caused by a vast array of genetic mutations, all different in nature

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16
Q

What makes PIDs heterogenous?

A

PIDs can be caused by a vast array of genetic mutations, all different in nature

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17
Q

What makes PIDs heterogeneous?

A

PIDs can be caused by a vast array of genetic mutations, all different in nature

18
Q

Why is it important to report a PID case, even if only one patient in the world is known to have it?

A
  • other patients may be discovered
  • rare PID patients can tell a lot about the human immune system
19
Q

Why is early PID diagnosis critical?

A
  1. Appropriate treatment can be given
  2. Improved prognosis
  3. Reduced mortality
  4. It is cheaper to treat diagnosed PID than undiagnosed PID
20
Q

PIDs are monogenic diseases. What does that mean?

A

It means that they are caused by rare mendelian mutations, inherited as AR, AD, and XL (manifest in boys, girls are healthy carriers)

21
Q

Why can immunological phenotypes vary in PID patients with the same genes?

A

Some mutations are more damaging than others, however, different genetic variants in the same gene or non-genetic factors such as age and environment can contribute to the phenotype.

22
Q

Why is it important to look for causative mutations in rare PID patients?

A
  1. Allows specific diagnosis for the patient (helps prognosis + treatment)
  2. Allows gene therapy
  3. Helps diagnosis of future patients
  4. a Better understanding of the human immune system
  5. Improves the understanding of mechanisms related to common diseases
  6. Helps design new therapies for common diseases
23
Q

What are the pros of nxt generation sequencing?

A
  1. Cheap and fast
  2. Finds nearly all variants in exome / genome
24
Q

Name some PID classifications

A
  1. Affecting cellular and humoral immunity
  2. Antibody deficiency
  3. Defects in phagocyte nr or function
  4. Autoinflammatory diseases
  5. Bone marrow failure
  6. Immunodef with syndromic features
  7. Immune dysregulation
  8. Defects in innate immunity
  9. Complement deficiency
  10. Phenocopies of inborn errors of immunity
25
Q

Name two ways in which two different mutations in one gene can cause PIDs

A

Through loss of function or gain of function.

26
Q

What is SCID?

A

Severe Combined Immune Deficiency

Defects in multiple genes which lead to immu def

27
Q

What is the hallmark of SCID?

A

Very low T-cell counts

28
Q

What is the most common SCID?

A

SCID-X1 - mutation in the IL2RG gene

29
Q

How does SCID-X1 affect immune cells?

A

Mutations in the IL2RG gene encode receptors for various cytokines.

IL-7 required for T-cell diff
IL-15 needed for NK cell development
IL-4 and IL-21 needed for B-cell signaling (low Ig production)

In SCID-X1, T-cells and NK cells are absent as they cannot develop at all and B cells have heavily impaired functions

30
Q

What is a leaky SCID?

A

Mutations in SCID-typical genes, but the created proteins do not completely lose their functions. Instead it is impaired.

31
Q

What genes does Omenn syndrome affect?

A

RAG1 and RAG2 genes.

32
Q

What is typical of CID?

A
  1. Defect T-cell receptor signaling
  2. Defect NF-kB signaling, impairing T-cell activation
  3. MHC-II deficiency, impairing Ag presentation to CD4+ T-cells
33
Q

What is used for SCID detection in newborn babies?

A

TREC quantification.
(T-cell Receptor Excision Circles)

34
Q

What is important to do when trying to protect a patient who suffers from SCID?

A

Isolate them as well as possible and try to prevent them from being infected with any virus or pathogen. Also Immunoglobulin supplementation.

35
Q

What does HSCT do?

A

HSCT is a curative treatment for SCID where a patient receives a bone marrow transplant from a donor. The patient’s original bone marrow stem cells are eradicated and completely replaced with donor cells.

36
Q

What are the risks tied to HSCT?

A

Latent and chronic infections. Also graft-versus-host disease.

37
Q

Who is the target of gene therapy in PID patients?

A

PID patients over 30 years old.

38
Q

Briefly describe how gene therapy works.

A

A set of stem cells is taken from the patient. They are then infected with a virus which is carrying a healthy copy of the gene. The virus then infects the stem cells and inserts the gene into the genome. The cells containing the healthy gene are then put back into the host.

39
Q

What is the most common type of PID?

A

Antibody deficiencies (>50%)

40
Q

What are the four subcategories of antibody-deficient PIDs?

A
  1. Severe reduction of Ig isotypes with decreased or absent B-cells (agammaglobulinemia)
  2. Severe reduction in at least 2 Ig isotypes with normal or low nr of B-cells (CVID phenotype - not covid :)
  3. Severe reduction in serum IgG and IgA with normal/elevated IgM. Hyper IgM means class-switching recombinant defect.
  4. Isotype, light chain, or functional deficiencies with normal nr of B-cells
41
Q

What is the most common cause of agammaglobulinemia?

A

Mutation in BTK (85% of the time). Impairs B-cell development in the bone marrow. B-cells are absent.

42
Q

Where is the BTK gene found?

A

On the X-chromosome. Boys will be affected.

43
Q

Deficiencies in which enzymes lead to (wrong) class-switching recombination or somatic hypermutation

A

Activation-induce cytidine deaminase (AID) and Uracil N-glycosylase (UNG)

44
Q

What is a treatment for patients with antibody deficiency?

A
  1. Injecting antibodies, mainly IgG. Other Ig isotypes are not provided.
  2. In severe cases, HSCT

Advanced Immunology and Cell Biology (8 decks)

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