Primary immune deficiencies - parts 1 Flashcards

1
Q

What is the major hallmark for an immune deficiency

A

Recurrent infections

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2
Q

What is the Acronym used to identify immune Deficiency

A
  • S - Serious infections - unresponsives to oral antibiotics
  • P - Persistent infections - chronic infections, early damage
  • U - Unusual infections - unsaul organism and sites
  • R - Recurrent infections - Two major or one major and one recurrent minor infections in one year
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3
Q

What are other features that may suggest immune deficiency

A
  • Weight loss
  • Failure to thrive
  • Chronic Diarrhoea
  • Severe skin rashes - Eczema
  • Mouth ulcers
  • Unusual autoimmune disease
  • Family history
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4
Q

How do we classify immune deficiencies in to categories

A
  • Primary - rare, >200 diseases
  • Secondary - common, subtle, often involves more than 1 part of the immune system
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5
Q

What conditions are associated with secondar immune deficiency

A
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6
Q

What are the compenents of the innate immune system

A
  • Cells
  1. Neutrophils
  2. Macrophages
  3. Mast cells
  4. NK cells
  • Proteins
  1. Complement
  2. Acute phase proteins
  3. Cytokines
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7
Q

What are the functions of the innate immune system

A
  1. Rapid clearance of organism
  2. Stimulates the aquired immune system
  3. Buys time while the aquired immune system is being activated
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8
Q

What are the components of the aquired immune system

A
  • Cells
  1. ​B lymphocytes
  2. T lymphocytes
  • Proteins
    1. ​Antibodies
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9
Q

What are the features of the aquired immune responce

A
  • Aquired as an adaptive responce to an antigen
  • Not gentically encoded
  • Responsive is unlimited all molecules ever
  • High specific
  • Immunological memory
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10
Q

Give examples of phagocytes

A
  • Neutrophils
  • Monocytes/macrophages
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11
Q

What are the functions of phagocytes

A
  • Initiation and amplification of the inflammatory responce
  • Scavenging of cellular and infectious debris
  • Ingest and kill microorganisms
  • Produce inflammatory molecules which regulate other components of the immune system
  • Resolution and repair
  • Bacteria and fungi
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12
Q

what are the clinical feature sof phagocyte deficiencies

A
  • Recurrent infections
  • Organisms
  • Common bacteria: Staph aurous
  • Unusual: Burkholderia cepacia
  • Mycobateria: atypica and TB
  • Fungi: candida and spergillus
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13
Q

What can go wrong in the cycle of a neutrophil which can lead to an immune deficiency

A
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14
Q

What happens when theres is a phagocytic defect in phagocyt production, mobilisation and recruitment

A

Failure to produce neutrophils due to:

  1. ​Failure of stem cells to differentiate along myeloid lineage
  • ​Primary defect: Recticular dysgenesis
  • Secondary defect: after stem cell transplantation ​​​​​
  1. Neutrophil maturation specific failure
  • Kostmann syndrome: severe congenital neutropaenia
  • Cyclic neutropaenia: Episodic every 4-6 weeks
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15
Q

What is Kostmaan Syndrome

A
  • Rare autosomal recessive disorder: Defect in specific neutrophil maturation
  • Causes severe chronic neutropenia - <200 ul
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16
Q

What are the clinical presentation of Kostmann syndrome

A

Infections - within 2 weeks after birth

  • Recurrent bacterial infections
  • Systemic or localised infection

Non specific features: fever, irritability, oral ulcerations and failure to thrive

17
Q

What is the managment of Kostmann syndrome

A

Supportive treatments

  • Prophylactic antibodies
  • Prophylactic antifungals

Definitive treatment

  • Stem cell transplantation : as defect is in neutrophil precursor
  • Granulocyte colony stimulating factor G-CSF - growth factor to assist maturation
18
Q

What would be expected if patient had defect in endothelial adheison molecule binding of neutrophil

A
  • Clinical features - Recurrent bacterial and fungal infections
  • Blood count - Very high neutrophil counts
  • Site of infection: Deep tissue infections with no pus formation
19
Q

What is leukocyte adehsion Deficiency

A
  • Failure to recognise activation markers expressed on endothelial cells
  • Neutrophils are mobilised but cannot exit the bloodstream
  • Rare primary immunodeficiency
  • Genetic defect in leukocyte intigrins
  • Clinical picture: marked leukocytosis with localised fungal and bacterial infections which are hard to detect
20
Q

How do pagocytes recognise a pathogen

A

PRRs: PAMPS

21
Q

What types of defects can arise in phagocyt recognition of pathogen

A
  1. Direct recognistion defect
  2. Indirect recognistion defect
22
Q

What are the types of pathogen recognistion receptors on phagocytes- Direct recognistion

A
  • Toll like receptors
  • Scavenger receptors
  • Lectin receptors

Therse can recognise - bacterial sugars and lipopolysaccharides

23
Q

How do phagocytes carry out indirect recognition

A

Opsonins

  • These molecules act to enhace phagocytosis by binding to pathogen
  • Complement C3b, IgG, C reactive protien

​ Binding to receptors on phagocyte surface

  • FC receptor expressed on phagocyte - allows binding of antibody that is bound to an antigen
  • Complement receptor 1 - CR1 on phagocytes - bind complement fragments which are also bound to antigens
24
Q

What are the defects in recognition

A
  • Defect in opsonin receptors - defective phagocytosis - redunancy means that this doent cause significant disease
  • Defect in production of complement or antibodies- inefficient opsoniation - Functional defect of phaocytosis
25
Q

What are the defects in phagocytosis and killing of pathogen

A

Failure of oxidative killing mechanisms: chronic granulomatous disease

26
Q

What is chronic granulomatous disease

A
  • Absent of respiratory burst
  • Deficiency of the intracellular killing mechansim of phagocytes
  • Commenest in NADPH - X-linked
  • Inability to generate oxygen free radicals (ROS/RNS)
  • cannot kill organism
27
Q

How does this disease cause formation of granulomas

A
  • Excessive inflammation
  • Failure to degrade chemoattractants and antigent - so more and more phagocytes
  • Persistent accumulation of neutrophils activated macrophages and lymphocytes- Granuloma
28
Q

What are the features of chronic granulomatous disease

A
  • Recurrent Deep Bacterial infections
  • Esp - Staphylococcus, Aspergilus, Pseudomonas cepacia
  • Recurrent fungal infections
  • Failure to thrive
  • Lymphadenopathy and hepatoslenogemaly
  • Granuloma formation
29
Q

What Lab investigation will be carried out for chronic granulomastous disease

A

NBT TEST

  • Feed patient neutrophils source of E.coli
  • Add dye sensitive to H2O2
  • If production of hydrogen peroxide by neutrophils then will change colour
30
Q

What is the treatment for CGD

A
  • Supportive - phrophylactic anti-fungals and antibiotics
  • Definitice - Stem cell transplantation
31
Q

Why is it important to activate other components of the immune system by phagocytes

A
  • Intracellular organism: can hide from immune cells in other cells - Salmonella, chlamydia and Rickettsia
  • Some can hide within immune cells -Mycobateria
  • There for need speficic cells to deal with these
32
Q

How do macrophages defend againt intracellular pathogens

A

Activates IL-12:IFNy network

  • Infected macrophages -> IL2 -> stimulate TH1 cells -> IFNY -> acts on macrophages -> stimulate TNF -> Which activates NADPH Oxidase -> Stimulation of oxidative pathways
33
Q

What are the kind of defects IL-12:IFNY

A

Single gene defects

  • IFNy receptor deficiency
  • IL-12 defiency
  • IL-12 receptor deficiency
34
Q

What can IL12:INFy defects cause

A
  • Myconacterial infections - Tb and atypical pneumonia
  • Salmonella !!
35
Q

What are the different types of investigations to be carried out for phagocyte function

A
36
Q

Summary

A
37
Q

What is the Agressive infection managment for phagocyte deficiencies

A

Infection prophylaxis

  • Septrin
  • Itraconazole - antifungal
  • Oral/Iv antibodies
  • Surgical draining of Abscesses
38
Q

What is the defenitive therapy for phagocyte deficiencies

A
  • Bone marrow transplantation

Spefific treatment for CGD

  • Gama interferone therapy
  • Gene therapy