unit 8 seminar: the immune system evelyn i. milian instructor sc246: fundamentals of microbiology

Unit 8 Seminar:The Immune System

Evelyn I. Milian

Instructor

SC246: Fundamentals of Microbiology

Microbiology: Unit 8 Seminar – The Immune System

Seminar Application Questions

1. The Complement system is an important part of the innate immune system that has far-reaching effects on the body’s ability to fight off infection. Many pathogens have the ability to affect or disable individual proteins within the Complement system. In your opinion, which Complement protein (C5a? C1?) would be most devastating to the host immune system if it were to be inactivated by a particular pathogen? Why?

2. As you have learned in this unit, the immune system does an exceptional job in clearing infections from the host. However, on occasion the immune system can actually make an illness worse by overreacting to a potential pathogen. One example is a phenomenon called “cytokine storm”. This occurrence takes place when the body is infected by specific pathogens. Some examples include the influenza virus that caused the 1918 Spanish Flu epidemic and more recently the SARS epidemic in 2003. What occurs during “cytokine storm” and how does it affect the host? Find an example of a more recent disease (hint: look at the flu virus) that induces cytokine storm.

3. Human society has evolved significantly over the past few decades. Populations of humans used to inhabit wide-open spaces and rarely had contact with large crowds of people. However, modern society requires people to live in very tight quarters and come into contact with possibly hundreds or thousands of people in a single day. Consider cities like New York City and Tokyo, Japan. Occupants in these cities are packed in tightly into subway systems and overcrowded conditions. When people in Japan are ill, they wear face masks to protect others, while in New York City this is not done. What are some other ways that people in these cities (and other large cities around the world) deal with potential exposure to pathogens?

Evelyn I. Milian - Instructor 2


3

Innate or nonspecific immunity (nonspecific defenses) Body’s defenses against any kind of pathogen (microorganism capable of

causing disease); they are present in our bodies at birth. Adaptive, acquired or specific immunity (specific defenses)

Body’s defenses against specific pathogens. Acquired immunity adapts or adjusts to handle a particular microbe. These defenses are obtained during the life of the individual. Unlike innate immunity, adaptive immunity is slower to respond, but it has a memory component.

Evelyn I. Milian - Instructor


Blood Cells(Formed Elements)

Blood contains erythrocytes (red blood cells) and leukocytes (white blood cells).

The second line of defense of the innate immunity includes phagocytes, white blood cells that engulf and digest microorganisms or other particles that are harmful to the body (phago = eat; cyte = cell).

Macrophages, neutrophils, dendritic cells, eosinophils

4


5

Stages of the Mechanism of Phagocytosis

1) Chemotaxis: chemically stimulated movement of phagocytes to a site of damage.

2) Adherence: attachment of the phagocyte to the microbe or foreign material.

3) Ingestion: phagocyte engulfs the microbe (forming a phagosome).

4) Digestion: phagocyte releases lysozyme and digestive enzymes to degrade the microbe.

5) Killing and Discharge: the chemical substances released by the phagocyte kill the microbe and waste material is discharged.



6

Innate Immunity – Second Line of Defense: INFLAMMATION

Inflammation is a nonspecific defensive host response to tissue damage characterized by the following signs and symptoms:Redness

Pain

Heat

Swelling (edema)

Inflammation can also cause loss of function sometimes, depending on the site and extent of the injury.



7


8Evelyn I. Milian - Instructor


Innate Immunity – Second Line of Defense: ANTIMICROBIAL SUBSTANCES: The Complement System


The Complement System is a group of plasma proteins that activate one another to help destroy invading microorganisms.

Complement proteins are activated in a cascade, a set of reactions that amplify some effect—that is, more product is formed in the second reaction than in the first, still more in the third, and so on. Complement is activated in several ways.


10



CLASSICAL

PATHWAY

OF

COMPLEMENT

ACTIVATION


12

The Result of Complement Activation



13

The Result of Complement Activation

(a) C3a and C5a bind to mast cells, basophils, and platelets to trigger the release of histamine, which increases blood vessel permeability.

(b) C5a functions as a chemotactic factor that attracts phagocytes to the site of complement activation.



14

The Complement system is an important part of the innate immune system that has far-reaching effects on the body’s ability to fight off infection. Many pathogens have the ability to affect or disable individual proteins within the Complement system. In your opinion, which Complement protein would be most devastating to the host immune system if it were to be inactivated by a particular pathogen? Why?

Application:Question Number 1


Innate Immunity – Second Line of Defense: ANTIMICROBIAL SUBSTANCES: The Complement System

Complement deficiencies can result in an increased susceptibility to disease.

Some bacteria evade destruction by complement by means of:

capsules, surface lipid-carbohydrate complexes, and enzymatic destruction of C5a (the fragment that serves as a chemotactic factor that attracts phagocytes).



16

Innate Immunity:

NonspecificDefenses of the Human

Body

Innate Immunity:

NonspecificDefenses of the Human

Body


Adaptive Immunity Includes Antibody-Mediated Immunity (Humoral Immunity by B Cells)

17


T-Cells and Cell-Mediated Immunity

18

Cytokines: small proteins made by body cells (including lymphocytes and APCs) that act as chemical messengers in the immune system affecting the behavior of other cells, such as macrophages and T cells.

Cytokines stimulate or inhibit cell growth and differentiation, regulate immune responses, or aid nonspecific defenses.

Cytokines directly or indirectly may induce fever, pain, and the proliferation of T cells.



Application – Question Number 2

As you have learned in this unit, the immune system does an exceptional job in clearing infections from the host. However, on occasion the immune system can actually make an illness worse by overreacting to a potential pathogen. One example is a phenomenon called “cytokine storm”. This occurrence takes place when the body is infected by specific pathogens. Some examples include the influenza virus that caused the 1918 Spanish Flu epidemic and more recently the SARS epidemic in 2003.

What occurs during “cytokine storm” and how does it affect the host? Find an example of a more recent disease (hint: look at the flu virus) that induces “cytokine storm”.



Cell-Mediated Immunity: Cytokine Storm


A cytokine storm (hypercytokinemia) is a potentially fatal immune reaction consisting of elevated release of cytokines.

Normally, the release and action of cytokines is kept in check by the body. However, sometimes the reaction becomes uncontrolled, and too many immune cells are activated at once. This event can lead to severe damage to body tissues and organs.

The precise cause is not fully understood, but some triggers of cytokine storm may include:

Avian influenza virus (H5N1), Swine flu virus (H1N1; 2009 outbreak), graft versus host disease, sepsis


Application – Question Number 3


Human society has evolved significantly over the past few decades. Populations of humans used to inhabit wide-open spaces and rarely had contact with large crowds of people. However, modern society requires people to live in very tight quarters and come into contact with possibly hundreds or thousands of people in a single day. Consider cities like New York City and Tokyo, Japan. Occupants in these cities are packed in tightly into subway systems and overcrowded conditions. When people in Japan are ill, they wear face masks to protect others, while in New York City this is not done.

What are some other ways that people in these cities (and other large cities around the world) deal with potential exposure to pathogens?


Tracking Disease in the Population: Public Health Organizations

Centers for Disease Control and Prevention (CDC): a branch of the U.S. Dept. of Health and Human Services (with headquarters in Atlanta, GA). Website: www.cdc.gov.

Collects and analyzes epidemiological information in the United States.

Publishes “Morbidity and Mortality Weekly Report” (MMWR).

World Health Organization (WHO): international agency in Geneva, Switzerland. Website: www.who.int/en/

Coordinates and sets up programs to improve health in more than 100 member countries.

Publishes “Weekly Epidemiological Record”.



References Bauman, Robert W. (2012). Microbiology with Diseases by Body System. Third

Edition. San Francisco, CA: Pearson Education, Inc.-Benjamin Cummings. Black, Jacquelyn G. (2005). Microbiology, Principles and Explorations. Sixth Edition.

NJ: John Wiley & Sons, Inc. www.wiley.com/college/black. Campbell, Neil A.; Reece, Jane B., et al. (2011). Campbell Biology. Ninth Edition. San

Francisco, CA: Pearson Education, Inc.-Pearson Benjamin Cummings. Cowan, Marjorie Kelly; Talaro, Kathleen Park. (2009). Microbiology A Systems

Approach. Second Edition. New York, NY: The McGraw-Hill Companies, Inc. www.mhhe.com/cowan2e

Dennis Kunkel Microscopy, Inc. (2011). http://www.denniskunkel.com Mader, Sylvia S. (2010). Biology. Tenth Edition. NY: The McGraw-Hill Companies, Inc. Martini, Frederic H.; Nath, Judi L. (2009). Fundamentals of Anatomy & Physiology.

Eighth Edition. San Francisco, CA: Pearson Education, Inc. – Pearson Benjamin Cummings.

Tortora, Gerard J.; Derrickson, Bryan. (2006). Principles of Anatomy and Physiology. Eleventh Edition. NJ: John Wiley & Sons, Inc. www.wiley.com/college/apcentral.

Tortora, Gerard J.; Funke, Berdell R.; Case, Christine L. (2010). Microbiology An Introduction. Tenth Edition. San Francisco, CA: Pearson Education, Inc.-Pearson Benjamin Cummings. www.microbiologyplace.com.


unit 8 seminar: the immune system evelyn i. milian instructor sc246: fundamentals of microbiology

Documents

innate immune system

host immune system

immune systemevelyn

innate immunity

adaptive immunity

specific pathogens

milian instructorevelyn

large cities