Introduction
We live in a sea of infectious agents, and we have evolved several mechanisms for protecting ourselves against those that are potentially pathogenic.
In a general sense, we can think of our defenses as consisting of three types.
- General, Non-specific (barriers and chemical defenses, such as skin and stomach acid)
- Non-specific recognition of certain molecular shapes on pathogens (the innate immune system)
- Highly specific (the acquired or adaptive immune system, which involves highly specific recognition of particular molecular shapes on pathogens and the ability to make highly specific antibodies to aid in the remove of specific pathogens)
Learning Objectives
After successfully completing this learning module, the student will be able to:
- List and explain non-specific barrier mechanisms for defense against microorganisms.
- Explain the difference between innate (natural) and adaptive (acquired) immunity and the limitations of each.
- Briefly describe the role of the following cell types:
> Macrophages and dendritic cells
> Neutrophils
> Eosinophils and basophils
> Natural killer cells
> Helper T-lymphocytes (helper T-cells)
> Cytotoxic T-lymphocytes (cytotoxic T-cells)
> Regulatory T-cells (Treg)
> B-lymphocytes (B-cells) and plasma cells
- Describe the cellular events that might be expected to take place when the innate immune system responds to injury cutting your foot while walking barefoot.
- Describe the cellular events that might be expected to take place in an unvaccinated person when the adaptive immune system responds to infection with a new strain of influenza virus.
- Define the terms "phagocyte" and "phagocytosis".
- Briefly explain the "complement system" and how it contributes to our body's immune defenses.
- List the classic signs of inflammation.
- Define what is meant by "antigen" and "epitope."
- Explain what is meant by "self tolerance" and how it develops.
- Explain what is meant by "antigen presentation."
- Explain the difference between passive and active immunity.
- Explain the difference between a primary and secondary immune response.
- Briefly describe the role of antibodies in an immune response.
- Briefly explain what a vaccine is and how it works.
- List the conditions that can cause immunodeficiency.
- Explain how HIV impairs immune function and how it evades destruction by the human immune system.
