Immunity Across the Ages

Question 1

Early in life

Answer 1

Maternal anitbodies and more of a Th2 response than Th1

Question 2

Older

Answer 2

Maintain Th2 response but other begin to drop off

Question 3

Important mother-fetus AB

Answer 3

IgG crosses placenta

IgA through suckling important for infection protection and bacterial development

Question 4

Order in which AB are synthesized in newborn

Answer 4

IgM, IgG, IgA

Question 5

If break of damage to gut tissue

Answer 5

IgG enters, effector T cells, neutrophils

Question 6

Neonatal intestinal

Answer 6

Lymphocyte honing and diff are decreased
Commensal density and complexity decreased
Small peyer’s patches

Question 7

Neonatal bronchial

Answer 7

Lower commensal density 
Lower TLR expression 
DCs lower
IL-4 is HIGHER 
IFNgamma lower
IL-10 lower

Question 8

Neonatal macrophages and neutrophils

Answer 8

Decreased TLR expression on monocytes…macros with decreased signal and cytokine production
Mature PMNs but weak antibacterial function, decreased chemotaxis and adhesion

Question 9

Neonatal dendritic cells

Answer 9

Decreased with decreased MHC 2, CD80, CD86, IL-12 production so decreased T cell priming
Decreased type 1 IFNs by DCs so decreased viral immunity

Question 10

Neonatal NK cells/T cells/complement innate

Answer 10

Decreased NK cells response to IL12, 15 and limited IFNgamma production
Innate T cells activate
Serum complement concentrations are low, low IgM means depend on alternative and lectin pathway

Question 11

Neonatal adaptive T cells

Answer 11

Naive CD4 development with bias to Treg
Th2>Th1
Poor antibody responses to polysaccharides (TI)
Impairment to respond to T-dependent antigens

Question 12

Neonatal adaptive B cells

Answer 12

B1 cells increased
B2 have decreased CD40, CD80/86, and CR2 leading to incomplete class switching
Memory Bs are formed
Decreased hypermutation so lower affinity
IgG rapidly declines after immunization becasue cannot support long term plasmablasts in bone marrow

Question 13

What molecule increases with age

Answer 13

Ink4a

Question 14

2 important vaccines for 65 and up

Answer 14

Flu and pneumococcal

Question 15

Inflammatory environment of older

Answer 15

Reduced AB avidity and/or number of responding cells
Expansion of CD8 cells that are skewed
Increased Th17 cells

Question 16

Elderly Thymus, lymph nodes, spleen

Answer 16

Decreased output of naive T cells 
Low output of naive B cells 
Reduced helper T function
Decreased memory B cell expansion 
Desensitized DCs and reduced TLR response...increased Tregs

Question 17

Innate - elderly

Answer 17

Shift of HSC from lymphs to myeloid 
Decreased PMN and resp burst 
Decreased TLR on DCs 
Decreased phagocytic and HLA2 function 
Increased pro-inflam cytokines that contribute to atherosclerosis, dementia, cancer

Question 18

T cells - elderly

Answer 18

Decreased naive, thymic involution, inverted CD8/CD4
Decreased TCR signlas
Increased neg regulator of CD4 signals
CD8 shift to highly differentiated CD28 effector memories
Decreased Treg cells

Question 19

B cells and others-elderly

Answer 19

Decreased telomerase and repair mechanisms accelerate aging and increase apoptosis
Decreased DTH response due to decreased endothelial activation because of decrease of TNF 
B cell repertoire decreased...decreased IgM and IgA...decreased class switch 
Lymphopenia