Immunodeficiencies Flashcards

0
Q

Definition of secondary immunodeficiency

A

Acquired as a consequence of environment insults and/or are a consequence of other disease processes

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1
Q

Definition of primary immunodeficiency

A
Present at birth
Usually due to inherited mutations in genes with immunological function 
Mostly autosomal recessive
Some x linked
Can be congenital
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2
Q

Infections associated with immunodeficiency

A

Characterised by infections that are Serious Persistent Unusual Recurrent
Nature or defect usually related to type of infections that occur
Bacterial infections-> antibody, complement or phagocyte deficiency
Viral/fungal-> associated with T cell defects and possible graft v host
Adaptive-> antibody/cell mediated/combined
Innate-> complement/phagocytes/NK cells

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3
Q

Primary antibody defects

A

More common in adults as don’t manifest till then
Diagnosis often delayed
Treat with immunoglobin replacement therapy
Disruption of B cell differentiation at different stages
Disruption of T cells

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4
Q

Primary B cell deficiency mechanism

A

B cell development disruption
Pre B to B-> x linked agammaglobinaemia
Th to B-> common variable immune deficiency IgA deficiency, IgA subclasses, hyper IgM syndrome
B to plasma cell-> common variable immune deficiency IgA deficiency, IgA subclasses

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5
Q

X linked linked agammaglobinaemia

A

Mutations in tyrosine kinase-> B cells don’t mature
Effects young children
Levels of IgG are greatly reduced
Lung and bone infections

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6
Q

Hyper IgM syndrome

A

Increased IgM
Can’t make the other isotopes
B cells can’t undergo class switching
Inhibits arks

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7
Q

Common variable immune deficiency

A

Low immunoglobin and antibody levels
Normal B cells present but disordered function
Some cases have impaired T cell signalling
Or failure of B cells to mature
Predisposed to development of recurrent infections

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8
Q

Di George syndrome

A

Primary T cell deficiency
Partial or complete failure of T cells to form
Failure of development of the third and fourth pharangeal pouches along with the parathyroid gland
Parathyroids-> hypocalcaemia
Great vessels-> congenital heat disease
Face-> dystrophic features
Thymus-> T cell deficiency(don’t develope), fungal and viral infections, graft v. Host if given a blood transplant

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9
Q

AIDS

A

Secondary T cell immunodeficiency
Seroconversion illness in 10-15%-> flu like symptoms as body tries to creat and antiviral response 8-10 weeks
Asymptomatic for many years-> cytoxic T cell response works well initially
Early symptoms-> persistent lymphadenopathy
AIDS-> defined as appearance of opportunistic pathogens

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10
Q

AIDS epidemiology and virology

A

Transmitted via sexual/blood contact
Tow retroviruses-> HIV1 and 2
Infects helper T cells by binding CD4 molecules
Diagnosis made by the detection anti HIV antibodies

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11
Q

AIDS immunology

A

Migrate to lymph and proliferate
HIV leads to destruction of CD4 cells
Decreased helper/suppressor T cell ratio in blood
Increasingly worse immune function
HIV targets CD4 as it’s primary receptor is a cytokine on CD4
Also on dendritic cells and macrophages-> dementia
Mutates rapidly so isn’t recognised by the immune system-> no adaptive immunity

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12
Q

SCID

A

Most common primary immunodeficiency of B and T cell function
Autosomal recessive or X linked
Different types depending on the mutation
Failure of B and T cell development precursors from stem cells
Small or absence thymus
Only treatable with bone marrow transplant or deadly
Presents in early years of life with thrush, pneumonia and diarrhoea

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13
Q

Neutrophil defects- reduced numbers

A

Lack of production:
-Primary-> kotsman cyclical neutropenia
-Secondary-> leukaemia, chemotherapy, infections
Excessive peripheral destruction

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14
Q

Neutrophil defects, abnormal function

A

Leukocyte adhesion deficiency in vessels-> can’t migrate
Chronic granulomatous disease:
X linked recessive
Blood and marrow neutrophils deficient in NADPH oxidase system-> unable to destroy bacterial
Foci of persisting infections-> skin, bones, lung, lymph
Granulomas develop
Abscesses

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15
Q

Complement deficiencies

A

Bacterial infections
Neisserial infections-> defects in alternative and membrane attack pathway
Immune complex disease-> defects in classical pathway and C3
C3b facilitates the binding in the liver required for complement complex removal-> accumulate
Immune complex disease-> C1 and 4 deficiency

16
Q

Categories of secondary immunodeficiencies

A

Iatrogenic-> immunosuppressive treatment, ablation/removal of lymphoid tissue
Malignancies-> of immune system-> leukaemia, lymphoma, myeloma
Some infections-> HIV, chronic malaria, measels
Malnutrition
Protein loosing diseases
Some chronic diseases eg renal
Burns