Immunity: Part IV

Acquired Immunity

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings

Remember: Types of Immunity

• Innate

• Acquired

– Is the body’s second major kind of defense

– Involves the activity of lymphocytes

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings

• A summary of innate and acquired immunity

INNATE IMMUNITY Rapid responses to a

broad range of microbes

ACQUIRED IMMUNITYSlower responses to

specific microbes

External defenses Internal defenses

Skin

Mucous membranes

Secretions

Phagocytic cells

Antimicrobial proteins

Inflammatory response

Natural killer cells

Humoral response(antibodies)

Cell-mediated response(cytotoxic lymphocytes)

Invadingmicrobes

(pathogens)

Notes Handout

Types of Immunity

Properties of Immunity

1.Specificity

2.Versatility

3.Memory

4.Tolerance

Notes Handout

Figure 14.16

Notes Handout

Figure 14.12

T Cells & Cell-Mediated Immunity

• T Cells must be activated by exposure to antigen

• T Cells recognize antigens when they are bound to membrane receptors of other cells

• Antigen membrane receptors are called– MAJOR HISTOCOMPATIBILITY COMPLEX

PROTEINS • Class I MHC • Class II MHC

T Cells & Cell-Mediated Immunity

• MHC Proteins• Class I

– Found on the surface of all nucleated cells– Peptides produced inside the cell are displayed on

the surface by Class I MHC proteins.

• Class II– Found on the surface of lymphocytes & phagocytes

• Called ANTIGEN-PRESENTING CELLS (APCs)

Types of T Cells

1. Cytotoxic T Cells

2. Helper T Cells

3. Memory T Cells

4. Suppressor T Cells

Notes Handout

Activation of Cytotoxic T Cells

MHC Class I clip

Helper T Cells• Activated by exposure to antigens presented by

Class II MHC proteins• Activated helper T cells perform two functions:

1. Coordinate specific & nonspecific defenses

2. Stimulate both cell-mediated & antibody-mediated immunity

• Activated helper T cells divide to produce:– More activated helper T cells– Memory T cells

• helper T cells clip

Memory T Cells

• Produced upon initial exposure to antigen, but do not respond to the antigen at that time.

• Provide a no-delay response to any FUTURE exposure to the same antigen– Immediate differentiation into cytotoxic T cells

and helper T cells

Suppressor T Cells

• Activated suppressor T cells dampen the responses of other T cells and B cells– Secrete suppression factors

• Act after the initial immune response

Notes Handout

Sensitization & Activation of B Cells

Sensitization & Activation of B Cells

Sensitization & Activation of B Cells

Sensitization & Activation of B Cells

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Antibody Structure

Antigen-antibody binding

antibody clip

Antibody (IgG) Function

• Neutralization• Agglutination and precipitation• Activation of complement• Attraction of phagocytes• Enhancement of phagocytes• Stimulation of inflammation

Notes Handout

Summary of the Immune Response and Its Relationship to Nonspecific Defenses

Notes Handout

Integration of the Lymphatic System with Other Systems