Lecture 16 - Immunocompromised Host Flashcards by Callum Donoher

What is Bronchiectasis?

The irreversible widening of airways (makes more susceptible to infection)

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What can lead to Bronchiectasis?

Unrecognised/undiagnosed Primary Immunodeficiencies

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What is the definition of an immunocompromised host?

State in which the immune system is unable to respond appropriately and effectively to infectious microorganisms

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What are the 2 types of immunity that could be affected in an immunocompromised host?

Cell mediated immunity (Cytotoxic response)

Humoral immunity

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Why can a T cell defect (Cell mediated immunity)) lead to a B cell defect (Humoral immunity)?

Helper T cells are needed to activate B cells

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What are the 2 ways a host can by immunocompromised?

Primary immunodeficiency
Secondary immunodeficiency

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What is primary immunodeficiency?

Congenital/gene defect leads to immunodeficiency in hosts

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What are the general ways a patient can have primary immunodeficiency?

Missing protein (cytokines or receptors)
Missing cells
Non-functional components

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What are the general ways a patient can have secondary immunodeficiency?

Its acquired (not born with)

Disease (e.g HIV)

Treatment:
(Chemotherapy-can end up getting febrile neutropenia)
Asplenic patients (encapsulated bacterial infection)
Organ transplant

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WHat are some examples of granulocytes?

Neutrophils
Eosinophils
Basophils

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What type of immunity is compromised in immunodeficent patients who have T cell or B cell deficiency?

Adaptive immunity

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What pneumonic do you use to determine if an infection suggests a possible immunodeficiency?

SPUR

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What does SPUR stand for when describing an infection that may suggest immunodeficiency?

Severe
Persistent
Unusual
Recurrent

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What is meant by an infection being described as Severe?
SPUR (Possibly immunocompromised)

Life threatening
So if not treated patient will die

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What is meant by an infection being described as Persistent?
SPUR (Possibly immunocompromised)

Despite recommended treatment the infection persists

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What is meant by an infection being described as Unusual?
SPUR (Possibly immunocompromised)

The site of infection is unusual (e.g deep tissues)
The type of microorganism is unusual (opportunistic infections e.g Candida albicans , shingles)

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What is meant by an infection being described as Recurrent?
SPUR (Possibly immunocompromised)

Multiple episodes/multiple infections

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What is a key identifier/presentation of a T cell deficiency?

Failure to thrive (growth, cant put on weight)

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What non infectious manifestations are patients with Primary Immunodeficiency more likely to get?

Autoimmune diseases
Malignancy

Inflammatory responses

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What types of defects cause Primary immune deficiency (PID)?

Antibody defects
T cell defects
Phagocytotic defects

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What is an example of a defect in B cell development that leads to an antibody defect?

Bruton’s disease

B for Brutons disease
B for B cell development defect leading to antibody defect

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What type of inheritance is Bruton’s disease?

Who are more likely to get Bruton’s disease?

X-linked inheritance

Males more likely to get it

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What are 2 examples of defects in antibody production (PID)?

CVID (Common Variable Immunodeficiency)
Hyper-IgM syndrome

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What is CVID (Common Variable Immmunodeficiency)?

NEEDS TREATMENT (MOST COMMON PRIMARY ANTIBODY DEFICIENCY)

B cells present but dont function properly

What are patients with CVID (Common variable immunodeficency) highly susceptible to?

Malignancy Autoimmune diseases

What 3 questions do you need to ask when suspecting a Primary Immunodeficency?

Is there complement? Is the complement in the correct amount? Is the complement functional?

What is an example of a T cell defect where a gene affecting T cell maturation and function is affected?

Severe Combined Immunodeficiency (SCID)

What is Severe combined immunodeficiency (SCID)?

When a gene affecting T cell maturation/function (defect) leads to a B cell defect Since the T cell defect also affects the B cells it’s COMBINED

What type of defect is Di George syndrome?

T cell defect

How does Digeorge syndrome lead to a T cell defect?

There is aplasia or hypoplasia of the thymus which is where T cells mature

What can go wrong in phagocytic defects?

Defects in respiratory burst Defect in fusion of lysosome/phagosome Defect in neutrophil production and chemotaxis

What is an example of a disease where theres a defect in respiratory burst?

Chronic Granulomatous Disease (CGD)

What is defective in Chronic Granulomatous Disease (CGD)?

NADPH Oxidase Therefore can do respiratory burst to destroy pathogens

What is an example of a disease where theres a defect in the fusion of lysosomes or phagosomes?

Chediak-Higashi syndrome

What type of defect is suggested when a patient has presentation of Primary Immunodeficiency diseases BEFORE age of 6MONTHS?

T cell defect Or Phagocyte defect

What type of defect is suggested when a patient has presentation of Primary Immunodeficiency diseases between the ages of 6 months and 5 years old?

B-cell antibody defect Phagocyte defect Think that after 6 months mothers antibodies would have depleted so likely a B-cell antibody defect

What type of defect is suggested when a patient has presentation of Primary Immunodeficiency diseases at 5 years or OLDER?

B-cell/antibody/complement Secondary immunodeficiency

What type of bacterial infections are people with a Complement deficiency as there immune defect vulnerable to and why?

Encapsulated bacteria (NHS): Neisseria species Haemophilus influenzae Streptococci (pneumoniae) Since complement is needed to opsonise encapsulated bacteria so phagocytosis can occur

What are the 2 most common Neisseria species that a complement deficient individual may get?

Neisseria meningitidis Neisseria gonorrhoeae

What infections are individuals with phagocytotic defects likely to get?

Staph a Candida spp (Skin/mucous infections Deep seated infections)

What type of infections are common in individuals with an antibody defect?

Sino-respiratory infections GI infections Malignancies Autoimmunity

Why are GI infections and Sino-respiratory infections common in people with antibody deficiency?

The antibody IgA is produced at mucosal surfaces and provides protection there If no IgA made you are vulnerable to infection at these surfaces

What type of infections are common with defects in T cells? What are the key ways that T cell defects infections are described?

Deep skin and tissue abscesses Opportunistic infections Failure to thrive Death if not treated

Check the Clinical cases for practice questions in the lecture from Slide 18.

How does a HRCT (High Resolution CT) appear in a patient with Chronic Granulomatous Disease (CGD)?

Halo signs

What supportive treatment can be given to manage Primary Immunodeficiency?

Infection prevention (prophylactic anti microbials) Nutritional support (Vit A/D)

How do you treat somebody if they have a Primary antibody deficiency or PID?

Immunoglobulin replacement therapy = Serum IgG as a lifelong treatmet

What are some examples of conditions that you’d treat with Immunoglobulin replacement therapy?

All of the antibody defects CVID Brutons disease Hyper-IgM syndrome

What are some common causes of secondary immune deficiencies which cause decreased production of immune components?

Malnutrition (often in the elderly) Infection (HIV) Haematological malignancies Splenectomy

What can be tested for if you suspect protein is being lost?

Albumin

What is an example of a way secondary immune deficiency can occur?

Loss of immune components (excess) E.g nephropathy, enteropathy

Why are patients with haematological malignancies more likely to get infections?

Chemotherapy-induced neutropenia Chemotherapy-induced damage to mucosal barriers Vascular catheters

How does chemotherapy damage to mucosal barriers make infection more likely?

Mucositis leads to normal flora being able to invade the mucosal barrier

What bacteria are likely to invade the body via a vascular catheter?

Staphylococcus epidermidis Staphylococcus Saprophyticus

What is febrile neutropenia?

When episodes of fever coincide with time of low levels of neutrophils

How dangerous is febrile neutropenia?

Very serious Acute medical emergency

What common form of primary antibody deficiency doe not require treatment?

IgA

What causes hyper IgM syndrome?

T cell defect of CD40L