Chapter 10

Immunology

>Protecting the pond from invaders

>Birth control in the society of cells

Infections

• Viruses

• Prions

• Bacteria

• Fungi

• Protozoans

• Parasites

• Cancer

Two Kinds of Immunity

• Natural Immunity: Non-specific, you are born with it

• Acquired immunity: Specific for a particular structure.

Natural Immunity

• Evolutionary learning

• It’s genetic: functions against– Bacteria (cell wall)– Viruses (double stranded RNA)

Natural immunity: Extracellular Infections

Macrophages: Attracted by local inflammation and damage

Gains a pool of “antigens” for presentation to cells of specific immunity

Sends out chemical signals that attract other immune cells

Natural immunity: Intracellular Infections

Natural Killer Cells

Attacks infected human cells

Also cancer cells

Sends out chemical messages that attract and excite other cells of the immune system

Specific Immunity

Involves Antibody molecules:

Unique molecules that can recognize specific structures: antigens

Immune Recognition

• Self tolerance

• Non-self intolerance

• Both are “learned”

• The environment of presentation is the key to the distinction

Antibody Molecules

Constant Region

Variable Region

Proteins, all of which are not directly coded in the DNA

The variable region “sticks” to something

Cells of Specific Immunity

• All are “born” in the bone marrow

• Maturation is “learning” how to make a single unique protein (antibody) that binds to something

• Splicing the DNA (cutting and pasting parts of the chromosome)

Self vs non-Self

• How does the immune system “know” something is an invader?

• How does the immune system “know something is self?

Immune Recognition

• Self = tolerance

• Non-self = intolerance

• Both are “learned”

• The environment of presentation is the key to the distinction

• OOPs; autoimmunity

B-Lymphocytes

• Born in the bone marrow

• Matures in the bone marrow

• Death to those that recognize self

• Life to those that don’t recognize self

• Environment determines the decision

Mature B-Lymphocyte encountering the antigen it recognizes

Free antibodies bind to their antigen which mark the carrier of the antigen for destruction

Compliment proteins

Antibodies mark organisms for destruction by phagocytes

Marked organism

T-Lymphocytes

• Born in the bone marrow• Matures in the thymus gland• Many types (eg. helper t-cells, cytotoxic t-cells

etc)• Keep their antigen on their surface and attack as

a cell• Macrophages “present” antigen to T-

lymphocytes• Death to those that recognize self

T-Lymphocyte being presented an antigen that it recognized by a macrophage

Divide

T-Lymphocytes attack as cells

Immune Responses

• Sometimes both B-cells and T-cells

• Sometimes only one

• Takes about 7 days

• After the response, memory cells remain to protect against future invasion by the same organism

• Then why can we get flu more than once?

• Mutations

Immune responses can be destructive

• Bacterial meningitis

• Shock

• Asthma

• Sepsis

Vaccines

• The best defense is a good offence

• Active immunization– Introduce the structures of the organism in

advance to create memory cells– Response of memory cells is immediate– Dead virus vaccines (not very effective)– Live virus vaccines (more effective but more

dangerous – you can get the disease)

Passive Immunization

• Rare but deadly circumstances– Snake bites– Toxins

>Introduce the compound slowly into another animal (cow, sheep, pig, goat etc) to develop an immune response

>Take the blood of the animal and use the

antibodies

>Infuse the antibodies in an emergency

Passive Immunization

However, you are now allergic to the serum of the animal used to make the anti-serum

(anaphylactic shock)

Blood Type Incompatibility

• The presence of antibodies against the type(s) of blood you don’t have

Inheritance

A A

B

B

AB

AB

AB

AB

AB

A O

B

B

AB

AB

AB

BO

BO

A A

B

O

AB

AB

AO

AB

AO

A O

B

O

AB

AB

AO

BO

O

What Does the Rh positive (+) or Rh negative (-) mean?

Rh Disease in the Newborn

• An Rh negative woman does not have the Rh antigen

• An Rh positive baby will immunize her to the Rh antigen

• First time- no problem

• Mother’s immune system will try to destroy the blood of subsequent Rh positive babies

Transplantation

• Only identical twins are molecularly identical

• “More or less” means a lot to the immune system

• Immunosuppressive drugs

Corticosteroids (synthetic glucocorticoids)

• Muscle wasting

• Fat deposition

• Arteriosclerosis

• Steroid diabetes

• Osteoporosis

• Immune deficiency

Immunodeficiency

• Some inherited

• Transplant

• Chemotherapy

• HIV

Human Immunodeficiency Virus

• A retrovirus

• Genetic material is RNA

• Infects T-Lymphocytes and Macrophages

• Reverse transcriptase

• High mutation rate

• Drugs: target the proteins

Autoimmune diseases• “Self” being viewed as “non-self”

– Lupus– Myasthenia gravis– Multiple Sclerosis– Arthritis– Celiacs disease– Etc

Why?

Cancer

• Your immune system should protect you

• An infection from within

• A maverick clone

• Looks like embryonic cells

• Doesn’t “pay attention” to the signals controlling cell division

Drugs

• Immunosuppression– Corticosteroids– Others

• Anti-inflammatory– COX 1– COX 2

• Cytokines