1. Body Defenses: Overview of Adaptive Defenses
Pages

2. Adaptive Body Defenses
third line of defense
Three important aspects:
1. It is antigen specific
2. It is systemic
3. It has memory
© 2015 Pearson Education, Inc. 2

3. Adaptive Body Defenses
Two types of immunity:
Humoral immunity  antibody-mediated immunity
Provided by antibodies present in body fluids
Cellular immunity  cell-mediated immunity
Targets virus-infected cells, cancer cells, and cells of foreign grafts
© 2015 Pearson Education, Inc. 3

4. Antigens - nonself Antigens (nonself)
Any substance capable of mobilizing the immune system and provoking an immune response
common antigens:
Foreign proteins (strongest)
Nucleic acids
Large carbohydrates
Some lipids
Pollen grains
Microorganisms
© 2015 Pearson Education, Inc. 4

5. Self-Antigens
Human cells have many surface proteins that our immune cells recognize
This concept restricts transplant potential
Another human’s cells can trigger an immune response because they are foreign
Blood type is a great example as agglutination takes place with a mismatch
© 2015 Pearson Education, Inc. 5

6. Agglutination Reaction

7. Cells of the Adaptive Defense System
Lymphocytes—respond to specific antigens:
B lymphocytes (B cells)
T lymphocytes (T cells)
Antigen-presenting cells (APCs)
Dendritic cells
Macrophages
B lymphocytes
© 2015 Pearson Education, Inc. 7

8. Lymphocytes Arise from hemocytoblasts of bone marrow
Become immunocompetent before they encounter the antigens they may attack
© 2015 Pearson Education, Inc. 8

9. Gaining immunocompetency
T cells
develop immunocompetence in the thymus
oversee cell-mediated immunity
B cells
develop immunocompetence in bone marrow
provide humoral immunity
Both groups move to lymph nodes to await antigen encounters

10. Lymphocyte Differentiation and immunocompetency
Haspi.org

11. Antigen-Presenting Cells (APCs)
Engulf antigens
Present fragments of antigen on their own surfaces
T cells recognize these fragments
T cells become activated
T cells release chemicals called Cytokines which:
enhance T cell activation
Stimulate activity of other T cells
Help to activate B cells and cytotoxic T cells
© 2015 Pearson Education, Inc.

12. Macrophages Arise from monocytes in bone marrow phagocytize pathogens
present parts of the antigens on their surfaces, for recognition by T cells
remain fixed in the lymphoid organs
Secrete cytokines
© 2015 Pearson Education, Inc. 12