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Flashcards in Immunodeficiencies Deck (17)

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


Definition of secondary immunodeficiency

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


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


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


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


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


Hyper IgM syndrome

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


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


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



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


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


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



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


Neutrophil defects- reduced numbers

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


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


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


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
Protein loosing diseases
Some chronic diseases eg renal

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