1. Unit Six: Blood Cells, Immunity, and Blood Coagulation
Chapter 34: Resistance of the Body to Infection. II. Immunity and Allergy Innate Immunity
Guyton and Hall, Textbook of Medical Physiology, 12th edition

2. Innate Immunity
Innate Immunity
Phagocytosis of bacteria and other invaders by wbcs and
cells of the tissue macrophage system
Destruction of swallowed organisms by stomach
acid and digestive enzymes
Resistance of the skin to invasion
Presence of antibacterial chemicals (i.e. lysozyme,
complement, NK cells, etc.)

3. Acquired (Adaptive) Immunity
Basic Types
Humoral or B-cell Immunity
Cell-mediated or T-cell immunity
Initiation of the Responses- antigens
MW greater than 8000
Epitopes or antigenic determinants on surface
Generally protein or large polysaccharides

4. Lymphocytes
T and B Lymphocytes
T lymphocytes migrate from the bone marrow to the
thymus where they mature and are responsible for
cell mediated immunity
B lymphocytes are preprocessed in the liver, then the bone
marrow and are responsible for antibody production
The “B” designation originated from the bursa of
Fabricius in the chicken.

5. Fig Formation of antibodies and sensitized lymphocytes from a lymph node in response to antigens

6. Lymphocytes (cont.)
Preprocessing of the T Lymphocytes-occurs
shortly before or just after birth
In the thymus each T cell develops specificity against
one antigen
Continues until there are thousands of different T cells
with specific reactivities against 1000s of antigens
T cells then migrate to the secondary lymphoid tissues
T cells capable of reacting against “self-antigens” are
destroyed instead of being released

7. Lymphocytes (cont.)
Preprocessing of the Lymphocytes
Instead of the whole cell developing reactivity against
the antigen, the B cells actively secrete antibodies that
are the reactive agents
Greater diversity than T cells: can form millions of
types of antibodies with different specific reactivities
T-Cells and B-Cell Antibodies React Highly Specifically
Against Specific Antigens-Role of Lymphocyte Clones

8. Lymphocyte Clones
Fig. 34.2

9. Lymphocyte Clones (cont.)
Millions of specific types of lymphocytes are stored in
the lymphoid tissues
Origin of the many clones of lymphocytes
Mechanism for activating a clone of lymphocytes
Role of macrophages
Role of the T cell in the activation of B cells

10. Humoral Immunity and the Antibodies
Formation of Antibodies by Plasma Cells
Formation of “Memory” Cells
Difference Between Primary and Secondary Responses

11. Humoral Immunity and the Antibodies
Fig Primary and secondary antibody responses

12. Antibodies (cont.)
Nature of Antibodies
Gamma globulins (immunoglobulins
b. MW between 170,000 and 970,000
c. Make up 20% of all the plasma proteins
d. Consist of heavy and light polypeptide chains
e. Have variable and constant regions

13. Antibodies (cont.)
Fig Structure of the typical IgG antibody

14. Antibodies (cont.)
Specificity of Antibodies-each antibody is specific
for a particular antigen
Ka is the affinity constant and a measure of
how tightly the antibody binds to the antigen

15. Blood, Lymph, B cell surface Cell bound to mast cells and basophils
Antibodies (cont.)
Classes of Antibodies
Class
Structure
Location MW
Half-Life
In Serum
Function
IgG
Monomer
Blood, Lymph, Intestine
170,000
23 days
Phagocytosis, neutralization, crosses placenta
IgM
Pentamer
Blood, Lymph, B cell surface
970,000
5 days
Primary response, phagocytosis, agglutination
IgA
Dimer
Secretions
405,000
6 days
Mucosal ab
IgD
B cell surface
175,000
3 days
Surface Ig on B cells
IgE
Cell bound to mast cells and basophils
190,000
2 days
Allergic Reactions,parasitic reactions

16. Antibodies (cont.)
Mechanism of Action of Antibodies (Direct)
Agglutination
Precipitation
Neutralization
Lysis

17. Mechanism of Action of Antibodies (Indirect)-the Complement System
Antibodies (cont.)
Mechanism of Action of Antibodies (Indirect)-the
Complement System
Fig. 34.6

18. Antibodies (cont.)
Classic Pathway
Opsonization and phagocytosis
Lysis
Agglutination
Neutralization of viruses
Chemostaxis
Activation of mast cells and basophils
Inflammatory effects

19. Activated T Cells and Cell-Mediated Immunity
Release of Activated T Cells From Lymphoid Tissue
and Formation of Memory Cells
APCs, MHC Proteins, and Antigen Receptors on
T lymphocytes

20. Activated T Cells and CMI (cont.)
Fig Activation of T cells requires interaction of T cell receptors
with an antigen that is transported to the surface of the APC
by a MHC protein.

21. Types of T Cells
Helper T Cells—Role in Overall Regulation of Immunity
Production of lymphokines (i.e. interleukins 2,3,4,5,6 and gamma interferon)
Specific regulatory functions of the lymphokines
Stimulation of growth and proliferation of cytotoxic T cells and suppressor T cells
Stimulation of B cell growth and differentiation to form plasma cells and antibodies

22. Types of T Cells (cont.)
Helper T Cells—Role in Overall Regulation of Immunity (cont.)
e. Activation of the macrophage system
f. Feedback stimulatory effect on the helper
cells themselves

23. Types of T Cells (cont.)
Fig Regulation of the immune system

24. Cytotoxic T Cells are “Killer” Cells
Types of T Cells (cont.)
Cytotoxic T Cells are “Killer” Cells
Fig Direct destruction of an invading cell by sensitize T cytotoxic cells

25. Types of T Cells (cont.)
Suppressor T Cells
Can suppress the functions of both T helper and
T cytotoxic cells
Regulatory cells—prevent excessive immune
reactions that might be damaging to the host

26. Tolerance
Tolerance to One’s Own Tissues
Results from Clone Selection During Preprocessing
Failure Leads to Autoimmune Diseases
Rheumatic fever
Glomerulonephritis
Myasthenia gravis
Systemic lupus erythematosus (SLE)

27. Immunization
Active Immunity
Artificially acquired
Naturally acquired
Passive Immunity

28. Allergy and Hypersensitivity
Type I Hypersensitivity (IgE antibody mediated)
Anaphylaxis
Urticaria
Hay fever
Mast cell involvement and histamine
Type II Hypersensitivity (Cytotoxic reactions)
Type III Hypersensitivity (Immune complex)
Type IV Hypersensitivity (Delayed cell mediated)