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Flashcards in Immunodeficiencies Deck (17)
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Definition of primary immunodeficiency

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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Definition of secondary immunodeficiency

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

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Infections associated with immunodeficiency

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

3

Primary antibody defects

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

4

Primary B cell deficiency mechanism

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

5

X linked linked agammaglobinaemia

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

6

Hyper IgM syndrome

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

7

Common variable immune deficiency

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

8

Di George syndrome

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

9

AIDS

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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AIDS epidemiology and virology

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

11

AIDS immunology

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

12

SCID

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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Neutrophil defects- reduced numbers

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

14

Neutrophil defects, abnormal function

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

15

Complement deficiencies

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

Categories of secondary immunodeficiencies

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

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