Immune basics Flashcards by Lisa Azizi

adaptive immune cells

CD4 T cells
B cell
CD8 T cell

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Innate immunity

neutrophil
macrophage
natural killer cells

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how does measles affect immune response ?

modify
decrease production and function of t cells

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secondary immunodeficiencies

infection
biochemical
malignancy
drugs

HIV
measles
mycobacterial

malnutrition
diabetes
Renal insufficiency

myeloma
leukaemia
lymphoma

steroids
antiproliferative
cytotoxic agents

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immunodeficiency - when can it be physiological?

neonates
elderly
pregnancy

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what can be a cause of secondary immunodeficiency

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3 condition that cause defective neutrophil production - do not produce

reticular dysgenesis
kostman
cyclic neutropenia

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reticular dysgenesis

reticular dysgenesis - severe scid - autosomal recessive nothing is produced

no myeloid / lymphoid

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kostmann

autosomal recessive
congenital neutropenia

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cyclic neutropenia

ELA-2 neutrophil elastase deficient

autosomal dominant

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leucocyte adhesion deficiency

the Cd18 b2 integrin is deficient

can’t bind to ICAM-1 so cannot exit blood

very high neutrophil count
nitrofurantoin test positive
no pus

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hwo do neutrophils normally enter tissue?

b2 integrin - CD18 combines with cd11a = LFA-1
lymphocyte function associated antigen 1

LFA-1 binds to ICAM-1

= neutrophil transmigration and adhesion

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b2 integrin ______, binds to ____ which forms ______

this then binds to intracellular adhesion molecule 1 on endothelial cells to mediate what?

CD18 combines with CD11a to produce LFA-1

LFA-1 binds to ICAM-1

allowing for neutrophil transmigartion and adhesion

in LAD this is stopped due to deficient b2 integrin = high neutrophilia, no pus formation

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4 mechanisms of phagocyte deficiency?

1) failure to produce
2) failure to leave blood (transmigration)2
3) failure to produce cytokines
4) failure to perform oxidative killing

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failure of oxidative killing?

chronic granulomatous disease

NADPH impacted (deficient)
= no ROS (HOCL)

persistent neutrophil accumulation = inflammation= pus = granuloma

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what kind of bacteria are you most susceptible to in CGD?

PLACESS

catalase positive

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catalase positive bacteria?

Pseudomonas,
Listeria,
Aspergillus,
Candida,
E.Coli,
Staph Aureus,
Serratia

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cytokine cycle macrophages and t cells?

IL12 produced
>
T cell stimulated
>
IFN gamma
>
back on macrophage
>
TNF-a / free radical

= NADPH oxidase = ROS

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which cytokine do macrophages rpoduce that stimulates t cells?

IL12

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t cell stimulates what?

ifn-y which then stimulates macrophages

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do macrophages or t cells produce TNF?

macrophages, which get there signalling from IFN-y

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what organisms infect macrophage?

atypical mycobacteria

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nitroblue tetrazolium blue test

is a test for oxidation - hydrogen peroxide

so no colour change in CGD - usually would be yellow > blue

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main test for CGD?

dihydrorhodamine

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phagocyte deficiency what type of infection?

skin and mouth mycobacterial infection - TB, atypical mycobacteria

neutrophil production

reticular dysgenesis kostmann cyclic neutropenia

For each of the following diseasesm state the expected neutrophil count, leucocyte adhesion markers, NBT/DHR test and presence of pus: kostmann

neutropenia / no neutrophils normal 3 no colour change no pus

For each of the following diseases state the expected neutrophil count, leucocyte adhesion markers, NBT/DHR test presence of pus: LAD

neutrophilia - very high absent cd18 colour change blue>yellow absent

For each of the following diseases state the expected neutrophil count, leucocyte adhesion markers, NBT/DHR test presence of pus: CGD

normal present no colour change present pus

For each of the following diseases state the expected neutrophil count, leucocyte adhesion markers, NBT/DHR test presence of pus: IL12/IFn-y

neutrophil count normal adhesion markers present normal present

phagocyte deficiencies - management?

IFN-y if CGD IgG SCT aggressive management of infection

what is main risk with NK deficiency?

increase risk of viral infection HSV,CMV,EBV, VZV

if nk deficient?

antiviral - aciclovir cytokine - IFN-a HSCT

recurrent infection with no neutrophils on FBC?

kostmann

high neutrophil, no pus formation recurrent infection?

LAD

recurrent infection, hepatsplenomegaly and abnormal DHR

cgd

infection w atypical mycobacteria? normal fbc?

ifn-y

regulatory protein in alt pathway?

factor h

main consequence of complement deficiency?

encapsulated bacter infection risk NHS neisseria meningitides haemophilus influenzae streptococcus pneumoniae

SLE and complement deficiencies?

c2 classical pathway promotes phagocyte mediated killing of apoptotic cells ineffective clearance = increase in self antigen and antibody

why is classical pathway associated w SLE?

immune complex clearance clearance of apoptotic cells : when this doesn't happen there is an increase in self antigen

clinical phenotype of complement deficiency?

SLE/C2 skin disease

what does functional complement deficiency mean?

active lupus = production of immune complexes = consumption of complement = functional deficiencyof c3, c4 as they are being used up

nephritic factors?

autoantibodies directed against c3 convertases = c3 activation and consumption

how to test classical pathway?

ch50 assay - c1,2,3,4,5-9

how to test altrnative pathway?

b,d,properidin c3, c5-9

severe childhood onset sle w normal c3, c4

c1q

causes of secondary immunodeficiency drugs

corticosteroids cytotoxic

causes of secondary immunodeficiency

infectionn biochemical - malnutrition, zinc/iron, renal impairment malignancy drugs

what disease is usually associated with nephritic factors?

glomerulonephritis: membranoproliferative

SCID - what is the gene in reticular dysgenesis

adenylate kinase 2 mitochondrial energy metabolism enzyme

most common type of SCID? what mutation causes?

x-linked xq13.1 Il-2R deficient cannot respond to cytokines

x linked SCID cell counts

clinical phenotype fo SCID

unwell by 3 months - maternal IgG dissapates fail to thrive diarrhoea skin disease

function of cd4+ cell?

full b cell response cd8 t cell monitor

what is diGeorge

22q11.2 failure of development of pharyngeal pouch t cell vibes

DiGeorge Catch-22

cardiac abnormality - tet of fallot abnormal face thymic aplasia cleft hypocalcaemia/ hypopara 22 chromosome

CD8 cytotoxic killing

fas ligand granzymes, perforins

underdeveloped thymus ?

b cell is fine t cell is low

MHC class 2

Bare lymphocyte syndrome Cd4+ cannot be selected = cd4+ deficiency

bare lymphocyte syndrome type 2 cell counts Cd8 Cd4 B IgG

normal low normal low (plasma need t cell interaction cd4)

ADA cell counts Cd8 Cd4 B IgG

low T low B low NK

x linked scid cell counts T B NK

t lymphocyte deficiency ?

viral infections fungal bacterial malignancy

how to investigate t cell deficiency?

WCC lymphocyte subset Immunoglobulins functional test of t cell HIV

Describe the typical levels of CD4, CD8, B cells, IgM and IgG that you would expect to see in the following diseases: SCID

CD4- low CD8-low B-can be normal / low IgM low/normal IgG low

Describe the typical levels of CD4, CD8, B cells, IgM and IgG that you would expect to see in the following diseases: Di George

low low normal IgM normal IgG low/normal

BLS type 2 Describe the typical levels of CD4, CD8, B cells, IgM and IgG that you would expect to see in the following diseases:

low, normal normal IgM normal IgG low

Fc constant region determines class of immunoglobulin t/f?

true this is heavy chain

effector function of immunoglobulin?

constant region of hevay chain Fc

role of antibody?

identify interact w complement, phagocyte, NK cell

Bruton x link hypogammaglobulinaemia

prevent maturation of b cell b cell tyrosine kinase gene BTK absence of mature b cells - absence of antibodies

boy 4 has had 5 otitis media episodes this year, he was recently discharged from hospital after admission with severe pneumonia presenting to GP with fungal growth on toe in 5th centile of growth

x linked hypogammaglobulinaemia

clinical features of antibody deficiency

bacterial infections toxins viral infections

b cell deficiency

wcc lymphocyte subset serum Immunoglobulin functional b cell function test igG antibody against s.pneumoniae igG is surrogate marker for cd4+ t helper cell fynction