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Immunology > Respiratory Immunulogy 1 > Flashcards

Respiratory Immunulogy 1 Flashcards

1
Q

Major hallmarks of immune deficiency?

A

Recurrent infection

SPUR:

Serious infections - unresponsive to oral antibiotics

Persistent infections - early structural damage and chronic infections

Unusual infections - unusual organisms at unusual sites; perhaps, opportunistic (people with normal immune systems would not get these)

Recurrent infections - two major or one major & recurrent minor infections in 1 year

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2
Q

Other features suggestive of primary immune deficiencies?

A

Weight loss

Failure to thrive (children)

Severe skin rash (eczema)

Chronic diarrhoea

Mouth ulceration

Unusual autoimmune disease

Family history - many conditions are genetic and Sudden Infant Death Syndrome may have occurred in family

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3
Q

Compare occurrence of primary and secondary immunodeficiences?

A

Primary - rare as few survive after birth

Secondary - common, often subtle and often involve more than one complement of the immune system

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4
Q

Conditions associated with secondary immune deficiency and who they occur in?

A

At extremes of age: Birth (neo-natal). pre-maturity, old age

Conditions: HIV (knocks out CD4 cells)

Measles (become susceptible to other infections)

Cancer (can affect bone marrow so less wbcs)

End stage renal disease

Iron deficiency (leads to superficial bacterial infections but can be solved)

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5
Q

Cells and proteins of the innate immune system?

A

Cells:

Macrophages

Neutrophils

Mast cells

Natural Killer cells

Proteins:

Complement

Acute phase proteins

Cytokines

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6
Q

How do innate immune system cells recognise pathogens?

A

Recognise structures that are unique to infectious organisms, e.g: bacterial sugars Essentially, same response in everyone

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7
Q

Functions of innate system?

A

Rapid clearance of microorganisms

Stimulates the acquired immune response

Buys time while the acquired immune system is mobilised

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8
Q

Describe the acquired immune system

A

ACQUIRED as a response due to exposure to an antigen and there is HUGE VARIATION

Repertoire is not genetically encoded and is acquired as an adaptive response to exposure to an antigen

Responsive to an unlimited no. of molecules with specificity

Basis of immunological memory

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9
Q

Cells and proteins of the acquired immune system?

A

Cells:

B lymphocytes

T lymphocytes

Proteins:

Antibodies

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10
Q

Which of the leukocytes are phagocytes?

A

Neutrophils

Monocytes/macrophages

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11
Q

Phagocyte function?

A

Important in defense against BACTERIA & FUNGI (not a huge role against viruses, which mainly reside in host cells) - particularly important at exposed sites

INITIATION and AMPLIFICATION of inflammatory response

Scavenging of cellular & infectious debris

Ingest and kill microorganisms

Produce inflammatory molecules, which regulate other components of the immune system

Resolution and repair

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12
Q

Clinical features of phagocytes deficiencies?

A

RECURRENT INFECTIONS - may affect common (skin, GI tract) unusual sites (e.g: causing a muscle abscess, spinal disc infection without trauma)

Organisms:

Common bacteria, e.g: Staph. aureus

Unusual bacteria, e.g: Burkholderia cepacia

Mycobacteria - both TB and atypical mycobacteria Fungi, like candida and aspergillus

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13
Q

Clinical importance of Burkhodleria cepacia?

A

Opportunistic pathogen affecting ONLY 2 groups:

People with PHAGOCYTE DEFICIENCIES

People with CF

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14
Q

Explain the importance of phagocytes

A

Chances of severe infection rise with decreasing neutrophil count

Normal neutrophil count - 4000-10000 per mm3

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15
Q

Life cycle of a neutrophil?

A

Mobilisation of phagocytes and stem cell precursors from bone marrow/within tissues

Endothelial adhesion markers are up-regulated at infection site

Stimulates neutrophil adhesion and migration into tissues (affected tissue sens signals)

Phagocytosis and killing of organism, resulting in neutrophil death

Also, there is activation of other components of immune system

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16
Q

Problems with neutrophil life cycle?

A

Defect of phagocyte production, mobilisation and recruitment - do not enter blood vessel; two types:

RECTICULAR DYSGENESIS

KOSTMANN SYNDROME

Failure to express leukocyte adhesion markers - LEUKOCYTE ADHESION DEFICIENCY

Antibody/complement deficiency - failure of opsonisation

Failure of oxidative killing mechanisms - CHRONIC GRANULOMATOUS DISEASE

Failure of cytokine production- gIFN and IL12 deficiency

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17
Q

Describe defects of phagocyte production

A

Failure to produce neutrophils due to:

Stem cells failing to differentiate along myeloid lineage causing one of two defects:

Primary defect - recticular dysgenesis (die within first few weeks of life)

Secondary defect - after stem cell transplantation

OR

Specific failure of neutrophil maturation:

Kostmann syndrome - severe congenital neutropaenia or cyclic neutropaenia (episodic neutropaenia every 4-6 weeks)

18
Q

Difference between recticular dysgenesis and Kostmann syndrom

A

Kostmann syndrome affects only neutrophils

19
Q

Describe what Kostmann Syndrome is and clinical presentation

A

Rare autosomal recessive disorder causing severe chronic neutropaenia (low neutrophil count)

Clinical presentation: Infections often within 2 weeks after birth - recurrent bacterial infections and systemic/localised infection

Non-specific features - fever, irritability, oral ulceration and failure to thrive

20
Q

Management of Kostmann syndrome?

A

Supportive treatment:

Prophyactic antibiotics

Prophylactic antifungals

Definitive treatment - mortality 70% in 1st year of life without definitive treatment:

Stem cell transplantation - defect is in neutrophil precursor, so replace all precursors with allogenic stem cells and start again

Granulocyte colony stimulating factor (G-CSF) - give specific growth factors to assist maturation of neutrophils until stem cell transplantation

21
Q

What is leukocyte adhesion deficiency?

A

Failure to recognise activation markers expressed on endothelial cells; so, neutrophils are mobilised but CANNOT EXIT BLOODSTREAM

22
Q

Characteristics of leukocyte adhesion deficiency?

A

Recurrent bacterial and fungal infections and very high neutrophil counts (leukocytosis)

Localised bacterial infections that are difficult to detect

Site of infection - deep tissues although NO PUS (dead and dying neutrophils) formation and NO REDNESS

23
Q

Describe how leukocyte adhesion deficiency arises

A

Caused by genetic defect in leukocyte integrins (CD18)

Results in failure of neutrophil adhesion and migration

24
Q

Describe methods of direct recognition of pathogens by phagocytes

A

Considerable overlap in recognition profiles

PATHOGEN RECOGNITION RECEPTORS (PRRs):

Toll like receptors

Scavenger receptors

Lectin receptors

Recognise MICROBIAL-SPECIFIC STRUCTURES:

Bacterial sugars

Lipopolysaccharide (LPS)

25
Q

What does genetic polymorphism in terms of direct recognition mean?

A

Exhibit genetic polymorphism - some associated with increased susceptibility to bacterial infection but most do not cause significant disease

26
Q

Describe methods of indirect recognition of pathogens by phagocytes

A

Via OPSONINS - act as binding enhancers for phagocytosis, inc. complement C3b, IgG antibody and C-Reactive Protein

OR

Can bind to receptors on phagocyte surface (express Fc RECEPTORS that allow bind of an antibody that is also bound to antigen); also express COMPLEMENT RECEPTOR 1 (CR1) which binds to complement fragments which are also bound to antigens

27
Q

Defects in opsonin receptors?

A

May cause defective phagocytosis, however, significant redundancy means that it generally does not cause harm

28
Q

Defects in complement or antibody productions?

A

Results in decreased efficiency of opsonisation causing a functional defect in phagocytosis, i.e: defect not in phagocytes but in other components of the immune response

29
Q

What causes Chronic Granulomatous Disease?

A

Failure of oxidative killing mechanisms:

ABSENT RESPIRATORY BURST - deficiency of intra-cellular killing mechanism of phagocytes

Inability to generate oxygen free radicals and so killing substances are not created; impaired killing of intracellular microorganisms

30
Q

Most common cause of chronic granulomatous disease?

A

Deficiency of p47phox component of NADPH oxidase (X-LINKED SO ONLY MALES EXPRESS IT)

31
Q

What are the consequences of chronic granulomatous disease?

A

Inability to clear organisms so EXCESSIVE INFLAMMATION - failure to degrade chemoattractants and antigens and there is persistent accumulation of neutrophils, activated macrophages and lymphocytes

Causes GRANULOMA FORMATION

32
Q

Features of chronic granulomatous disease?

A

RECURRENT DEEP BACTERIAL INFECTION, esp. Staphylococcus, Aspergillus, Pseudomonas cepacia; also, mycobacteria and atypical mycobacteria

RECURRENT FUNGAL INFECTION

FAILURE TO THRIVE

LYMPHADENOPATHY (enlarged lymph nodes) and HEPATOSPLENOMEGALY (liver and spleen enlargement) due to inflammation

GRANULOMA FORMARION

33
Q

How to test from chronic granulomatous disease?

A

NBT TEST (nitroblue tetrazolium): in petri dish, can the neutrophils kill, e.g: E.coli (dye that is sensitive to H2O2; so, if neutrophils produce hydrogen peroxide is produced by the neutrophils, dye changes colour

34
Q

Treatment of chronic granulomatous disease?

A

Supportive treatment:

Prophylactic antibiotics

Prophylactic antifungals

Definitive treatment:

Stem cell transplantation

Gene therapy

35
Q

What are intracellular organisms and give examples?

A

Hide from immune system by locating within cells, like Salmonella, Chlamydia, Rickettsia

Some hide within immune cells, particularly in macrophages, including mycobacteria species like TB (difficult to clear)

36
Q

Describe what occurs in infection with mycobacteria TB

A

Activated IL12 - gIFN network:

Infected macrophages are stimulated to produce IL12

IL12 induces T cells to secrete gamma interferon (gIFN)

Stimulates production of TNF

Activates NADPH oxidase

Stimulates oxidative pathways

Any defects of this pathway can cause susceptibility to mycobacterial infections

37
Q

Iatrogenic factor that increases TB risk?

A

Giving anti TNF drug can have a side effect of reactivating latent TB

38
Q

Defects that are associated with susceptibility to intracellular bacteria?

A

Single gene defects:

gIFN receptor deficiency

IL12 deficiency

IL12 receptor deficiency

Mycobacterial infection:

TB

Atypical mycobacteria

Salmonella

39
Q

Summarise congenital neutropaenia?

A

Neutrophil count - 0

Pus formation - None

Leukocyte adhesion markers- normal

NBT test - abnormal as no neutrophils

40
Q

Summarise leukocyte adhesion defect?

A

Neutrophil count -

Pus formaiton -

Leukocyte adhesion markers -

NBT test -

41
Q

Summarise chronic granulomatous disease?

A

Neutrophil count - normal

Pus formation - normal

Leukocyte adhesion markers - normal

NBT test - abnormal

42
Q

Summary of phagocyte deficiency treatment?

A

Aggressive management of infection:

Infection prophylaxis with Septrin and Itraconazole (antifungal)

Oral/intravenous antibiotics

Surgical draining of abscesses

Definitive therapy:

Bone marrow transplantation

Specific treatment for chronic granulomatous disease - gIFN therapy and gene therapy

Immunology (12 decks)

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