Lecture 16 - Immunocompromised Host Flashcards
What is Bronchiectasis?
The irreversible widening of airways (makes more susceptible to infection)
What can lead to Bronchiectasis?
Unrecognised/undiagnosed Primary Immunodeficiencies
What is the definition of an immunocompromised host?
State in which the immune system is unable to respond appropriately and effectively to infectious microorganisms
What are the 2 types of immunity that could be affected in an immunocompromised host?
Cell mediated immunity (Cytotoxic response)
Humoral immunity
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
What are the 2 ways a host can by immunocompromised?
Primary immunodeficiency
Secondary immunodeficiency
What is primary immunodeficiency?
Congenital/gene defect leads to immunodeficiency in hosts
What are the general ways a patient can have primary immunodeficiency?
Missing protein (cytokines or receptors)
Missing cells
Non-functional components
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
WHat are some examples of granulocytes?
Neutrophils
Eosinophils
Basophils
What type of immunity is compromised in immunodeficent patients who have T cell or B cell deficiency?
Adaptive immunity
What pneumonic do you use to determine if an infection suggests a possible immunodeficiency?
SPUR
What does SPUR stand for when describing an infection that may suggest immunodeficiency?
Severe
Persistent
Unusual
Recurrent
What is meant by an infection being described as Severe?
SPUR (Possibly immunocompromised)
Life threatening
So if not treated patient will die
What is meant by an infection being described as Persistent?
SPUR (Possibly immunocompromised)
Despite recommended treatment the infection persists
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)
What is meant by an infection being described as Recurrent?
SPUR (Possibly immunocompromised)
Multiple episodes/multiple infections
What is a key identifier/presentation of a T cell deficiency?
Failure to thrive (growth, cant put on weight)
What non infectious manifestations are patients with Primary Immunodeficiency more likely to get?
Autoimmune diseases
Malignancy
Inflammatory responses
What types of defects cause Primary immune deficiency (PID)?
Antibody defects
T cell defects
Phagocytotic defects
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
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
What are 2 examples of defects in antibody production (PID)?
CVID (Common Variable Immunodeficiency)
Hyper-IgM syndrome
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
