Section 1 GeneralSection 1 General Features of the Immune Features of the Immune

SystemSystem

1. 1. Cells of the immune systemCells of the immune system

(1) T lymphocytes

(2) B lymphocytes

(3) Macrophages

(4) Dendritic and Langerhans’ cells

(5) Natural killer (NK) cells

Slide 7.1

The T-cell receptor (TCR) complex: schematic illustration of TCR and TCRα and TCR β polypeptide chains linked to the CD3 molecular complex.

(From Robbins Basic Pathology ,2003 ）

Slide 7.2

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 Ⅱmolecule binds to the nonpolymorphic portion of the class

molecule. The interaction between Ⅱthe 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 7.8

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 7.5

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 7.6

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 7.7

Schematic diagram of HLA class I molecule.(From Robbins Basic Pathology ,2003 ）

Slide 7.3

Lymph node cortex showing a lymphoid folicle, the B cell-comaining area.

(From Robbins Basic Pathology ,2003 ）

Slide 7.4

A highly activated natural killer cell with abundant cytoplasmic granules. (Dr. Trace Worrell )

(From Robbins Basic Pathology ,2003 ）

2. Cytokines

messenger molecules of the immune system

(1) Categories(1) Categories ① Cytokines that mediate natural immunity

② Cytokines that regulate lymphocyte growth, activation, and differentiation

③ Cytokines that activate inflammation

④ Cytokines that stimulate hematopoiesis

(2) General properties of cytokines

① Many individual cytokines are produced by several different cell types.

② Cytokines induce their effects in three ways: autocrine effect paracrine effect endocrine effect

③ Cytokines mediate their effects by binding to specific high-affinity receptors on their target cells.

④ The effects of cytokines are pleiotropic

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