Section 1 General Features of the Immune System

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Section 1 General Features of the Immune System
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1. Cells of the immune system

• (1) T lymphocytes
• (2) B lymphocytes
• (3) Macrophages
• (4) Dendritic and Langerhans cells
• (5) Natural killer (NK) cells

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The T-cell receptor (TCR) complex schematic
illustration of TCR and TCRa and TCR ß
polypeptide chains linked to the CD3 molecular
complex.
(From Robbins Basic Pathology ,2003)
Slide 7.1
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Schematic representation of antigen recognition
by CD4 T cells. Note that the T-cell receptor
(TCR heterodimer) recognizes a peptide fiagment
of antigen bound to the major histocompatibility
complex (MHC) class ? molecule. The CD4 molecule
binds to the nonpolymorphic portion of the class
? molecule. The interaction between the TCR and
the MHC-bound antigen provides signal 1 for
T-cell activation. Signal 2 is provided by the
interaction of the CD28 molecule with the
costimulatory molecules (B7-1 and B7-2) expressed
on antigen presenting cell.) (From Robbins Basic
Pathology ,2003)
Slide 7.2
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Schematic illustration of antigen recognition by
CD8 T cells. Note that the T-cell receptor (TCR
heterodimer) recognizes a complex formed by the
peptide fragment of the antigen and MHC class I
molecule. The CD8 molecule binds to the
nonpolymorphic portion of the class I molecule
and thus acts as an accessory structure during
antigen recognition. (From Robbins Basic
Pathology ,2003)
Slide 7.8
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Schemattic representation of NK cell receptors
and killing. Normal cells are not killed because
inhibitory signals from normal MHC class I
molecules override activating signals. In tumor
cells, or virus-infected cells, reduced
expression or alteration of MHC molecules
interrupts the inhibitory signals, allowing
activation of NK cells and lysis of target cells.
(From Robbins Basic Pathology ,2003)
Slide 7.5
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Schematic representation of the HLA complex and
its subregions. The relative distances between
various genes and regions are not drawn to scale
. (From Robbins Pathologic Basis of Disease
,1999)
Slide 7.6
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Schematic diagram of HLA class I molecule.
(From Robbins Basic Pathology ,2003)
Slide 7.7
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Lymph node cortex showing a lymphoid folicle, the
B cell-comaining area.
(From Robbins Basic Pathology ,2003)
Slide 7.3
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A highly activated natural killer cell with
abundant cytoplasmic granules. (Dr. Trace Worrell
)
(From Robbins Basic Pathology ,2003)
Slide 7.4
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2. Cytokines

• messenger molecules of the immune system
• (1) Categories
• ? Cytokines that mediate natural immunity
• ? Cytokines that regulate lymphocyte growth,
  activation, and differentiation
• ? Cytokines that activate inflammation
• ? Cytokines that stimulate hematopoiesis

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(2) General properties of cytokines

• ? Many individual cytokines are produced by
  several different cell types.
• ? Cytokines induce their effects in three ways
• autocrine effect
• paracrine effect
• endocrine effect
• ? Cytokines mediate their effects by binding to
  specific high-affinity receptors on their target
  cells.
• ? The effects of cytokines are pleiotropic

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• 3. structure and function of histocompatibility
  antigens.
• 4. Disorders of the immune system
• Disorders of the hypersensitivity reactions
• Immune system autoimmune diseases
• immunologic
  deficiency syndrome