1. Game plan Lecture Lab Antibody- antigen binding Staph, Strep and
Humoral immunity
Cellular immunity
Clonal selection and immuno-
logical memory
Lab
Staph, Strep and
Enteric Unknowns

2. Antibodies
c. Antibodies shown via atomic force microscopy

3. Antibodies and antigens
Antigens (Ag):
- Protein or large polysaccharide
- Can be attached or free from
cell
- Each antigen contains multiple
epitopes that are recognized
by…
Antibodies (Ab):
- “Immuno- Globulin” proteins (Ig)
- Specific for 1 Ag epitope
Figure 17.1

4. Antibody structure
Figure 17.3

5. Antibody classes
Table 17.1

6. The two arms of adaptive immunity
Fig 17.18

7. Humoral immunity: control of freely circulating
pathogens
Figure Overview

8. T-dependent antigens T- dependent antigens Proteins (viruses,
bacteria, RBC)
and haptens

9. T-independent vs. T-dependent antigens
Repeating subunits such
as polysaccharides,
lipopolysaccharides,
and capsules
Proteins (viruses,
bacteria,RBC)
and haptens

10. Clonal selection Clonal selection outcomes Proliferation of
Ag-specific B cells and
TH cells
Differentiation of B cells
- Plasma cells
- Memory cells
Production of Ag-specific
IgG and IgM
Figure Overview

11. Clonal selection and immunological
memory

12. RESULTS: Antibody- Antigen Binding Agglutination
Activation of complement
Reduces number of infectious units to be dealt with
Causes inflammation and
cell lysis
Complement
Bacteria
Antibody-dependent
cell-mediated cytotoxicity
Opsonization
Coating antigen with antibody enhances phagocytosis
Antibodies attached to target cell cause destruction by macrophages, eosinophils, and NK cells
Eosinophil
Phagocyte
Large target cell (parasite)
Neutralization
Virus
Toxin
Blocks attachment of toxin
Blocks adhesion of bacteria and viruses to mucosa
Bacterium

13. Cellular immunity- control of intracellular
pathogens
Antigen presenting cells (APCs): Antigenic fragments of pathogens
are presented on specific cells (APCs) using MHC II complexes
- Dendritic cells
- Macrophage

14. Cellular immunity- APCs and TH cells
Helper T cells (TH or CD 4): recognizes APC and presented Ag 
activates cells related to cell- mediated immunity, macrophages,
NK cells, T cells, and humoral response (B cells).

15. Cellular immunity: infected host cells and CTLs
Infected host cells: self-cells that have been infected with a
pathogen (or are tumor cells) that present “endogenous antigens”

16. Cellular immunity: infected host cells and CTLs
Cytotoxic T cells (TC or CD8): differentiate into cytotoxic T
Lymphocytes (CTLs) that destroys target cells on contact

17. The two arms of adaptive immunity
Fig 17.18

18. Independent study Review humoral and cellular immunity
Prepare for Tuesday’s class:
Look through PowerPoint “Lecture 18”
Complete Lecture Assignment “Lecture 18 Pre-quiz” and bring
to class on 4/21 (optional: extra credit)
Read through the first 3 pages of handout (i.e. Components of
Ethical Questions, The Principles of Bioethics, and Focus on
Principles)
Be prepared for bioethical discussion on “Vaccination”