Reminders

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Reminders

• Exam 3-
• MC average 80

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Th cells

• Effector molecules are cytokines!
• Th cells require a couple of hours to produce
  their effector molecules.

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The Th1 cells
Crucial for leading immune responses against
intravesicular pathogens- Travel buddies with
effector Tc cells!
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Macrophage Activation

• Two primary signals activate mf
• CD40L on Th cell interacts with CD40 on mf.
• IFN-g

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What happens when the mf becomes activated?

• Expression secretion of cytokines
• TNF-a acts in synergy with IFN-g
• Upregulation of
• CD40, B7, TNF Receptors.

• Lysosomes fuse more efficiently to phagosome.
• Production of more ROI, Nitric Oxide,
  antimicrobial peptides.

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The Th1 cells produce other cytokines that
modulates the immune response
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Fig 6-35, Parham, p. 172
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The humoral immune response

• B cell activation

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The Big Picture

• Naive B cells congregate in the secondary
  lymphoid tissue.
• Ag stimulation retains them, lack of antigen
  results in their circulation.

IgM IgD
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B Cell Activation
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B cell Activation Requires Two Signals in order
to promote proliferation AND differentiation
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Signal 1 is mediated by the BCR complex
Co-receptor (not shown)
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• Receptor clustering activates RATKs, Blk, Fyn, or
  Lyn to phosphorylate ITAM sequences on Iga Igb.

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B cell Co-Receptor

• Complete Coreceptor found in mature B cells.
• CR2 (CD21)- Complement Receptor protein.
• binds to complement protein- C3d.
• CD19-
• P during cell signaling.
• TAPA-1 or CD81-
• unknown function

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Phosphotidyl-inositol 3-OH kinase (PI 3- kinase)
Jnk phosphorylates Jun activating it to bind FOS
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TI antigens B cell Activation
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General Characteristics of TI antigens

• Weak B cell response
• No memory B cells
• No affinity maturation
• Usually no class switching
• IgM response.
• There are two types
• TI-1 antigens TI-2 antigens