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Humoral or Ab response

1. Period of Ag eliminationFirst phase: 90% is removedthrough the lung,

liver & spleenextensive phagocytosis

Second phase: gradual catabolic degradation &

removal processenzymatic hydrolysis &

digestion

Third phase: accelerated removal of Ag

due to Ab combining w/ Ag, enhancesphagocytosis, digestion & removal

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First injection of Ag

Lag of several hours to several days

Latent/Induction

Few cells

Ab finds residual Ag

Antigen

Route of administration

Species of animalSerologic test

Ab is detected

(5thto 10thday)

Rises, reaches its peak, begins to dropIgM ----IgG

Primary Response

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Secondary Response

Accelerated/booster

Anamnestic response

2ndinjection of the

same Ag

Ab drops first

(still complexing w/ newly injected Ag)

Rises, reaches its peak & persist

for a longer period of time

Host is primed for that

particular Ag

Long-lived cells

More Ab production

More IgG than IgM(memory cells)

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Humoral or Ab response

1. Lag phasedelayed

response

2. Log phaseincrease Ab

production

3. PlateauAb titer is

stabilized

4. DeclineAb is cleared

Difference between

Primary and Secondary

Response

1. Ab titer: greater in

secondary response

2. Time course: shorter lagphase & extended plateau

in

secondary response

3. Ab class more IgG insecondary response

4. Ab affinity: greater in

secondary response

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Cellular Response

1. Describe localized reactions to intracellular microbes

2. Mediated by lymphocytes3. Occurs after Ag presentation & activation of T cells

Activationregulated by T helper & T suppressor

4. Certain T cells release lymphokinesactivate

macrophages5. Cytotoxic T cellsactivated by Ag & receive

assistance from helper cells to directly kill their target

cells

6. Helper T cells also cooperate w/ B cells in theproduction of Ab, which may arm killer cells carrying Fc

receptors

7. NK cells act nonspecifically, particularly against

cellular targets

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Cellular Response

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Cellular Response

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Perforin mediated killing

T cytotoxic & activated NK cells contain perforin whichpolymerizes to form a pore in the the target cells membrane and

granizymes (fragmentins) , a serine protease which are required

in some killing

Fas system

T cytotoxic cell delivers lethal hit to their target cells via

calcium independent mechanismFas system.

TC cell binds to the target cell through the Fas ligand & known

to induce apoptosis

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ADCC

kill their target cell coated with specific Ab

Macrophages

present the Ag to the T cells during the induction

phase & become activated in response to lymphokines

during the effector phase