1. Lecture 16 Cellular Cooperation and Antigen Recognition

2. Cellular Cooperation antigen T B Plasma CellsH
Study Guide
What are the cells involved in initiating an immune response?
Plasma Cells
Antigen presentation to T and B cells by APC
T cells elaborate cytokines to facilitate B cell proliferation and maturation
Antibody secretion by plasma cells
Antigen presenting cell

3. Antigen Presenting Cells
Must be capable of processing antigen from extracellular and intracellular pathogens
Must present processed antigen on MHC class I & II molecules
Must express co-stimulatory molecules (cytokines)

4. Types of Professional Antigen Presenting Cells
Macrophages/monocytes
Dendritic cells (e.g.., Langerhan’s cells)
B cells

5. Properties of Professional Antigen-Presenting Cells

6. Cellular Cooperation and Antigen Recognition+
APC
Extracellular
Antigen
Class II MHC-
associated
antigen
CD4+ Helper T Lymphocyte

7. The Role of Adjuvants Depot effect Macrophage activation
antigen persists for long period
resistance to rapid degradation
Macrophage activation
production of non-specific enhancing factors
Non-specific T cell signal
provides "second" signal to B cell normally provided by T cell
Study Guide
What are adjuvants?
What signal may be provided by the adjuvant that is missing in the response to poor antigens?
What is a depot?

8. Types of Adjuvants Freund's Complete Adjuvant (Water-in-oil emulsion)
mineral oil
emulsifying agent
microbial preparation (eg. heat-killed extract of Mycobacterium tuberculosis)
aqueous phase containing antigen
Aluminum Hydroxide Gel
Microbial Adjuvants
C. parvum
BCG
Peptides and Synthetic Polymers
Study Guide
What is adjuvant therapy?
What adjuvant(s) are most likely to be used in humans?

9. Effector Mechanisms
Mechanisms that are used by the immune system to eliminate pathogens (or other substances) from the body
Cellular effector mechanisms
Activated T cells
Natural killer cells
Humoral effector mechanisms (antibody)
Neutralization
Opsonization
Complement activation
Antibody-dependent cell-mediated cytotoxicity (ADCC)

10. Effector Activity Against Pathogens

11. Cytokines
Polypeptides produced by a variety of cell types including T lymphocytes.
Cytokine production is triggered by specific receptor binding and subsequent signal transduction pathways
Cytokine repertoire is dependent on cell type triggered, receptors present on that cell type.
Cytokines act on cells that possess receptors for them.

12. Lymphocyte Migration, Activation, and Effector Function Depends on Cell-Adhesion Molecules
A variety of cell surface polypeptides serve as receptors to ensure appropriate cell-cell interactions. These polypeptide include:
Selectins
Integrins
Immunoglobulin Superfamily
Mucin-like Vascular Addressins

13. T-cell Mediated Cytotoxicity
Necrosis
Programmed cell death or apoptosis

14. Summary
Effector cells and antibodies play critical roles in almost all adaptive immune responses
Antigen-presenting cells play critical role in processing and presenting antigen to T cells
Cytokines are released by a variety of cell types and regulate a variety of biological effects
T-cell mediated cell death is largely via apoptosis