Immune system dynamics

Figure 17.1

Antibody- antigen binding

Figure 17.1

Antigens (Ag)

Protein or polysaccharideCan be attached or free from cell

Antibodies (Ab)

Globulin proteinsSpecific for 1 (one) Ag

Lymphocytes

B and T cellsB cells produce Ab

Figure 17.1

How do we acquire immunity?

1. Humoral immune response

2. Cell-mediated immune response

Humoral Immunity- fighting antigens in the blood

The players involved:

- An antigen

- B cell with specific Ab

- Helper T cells

The product:

- Antibodies

- Clone army of B cells and T cellsspecific for the antigen

Figure 17.5 - Overview

How is a clone army made?

Primary vs. secondary exposure

The players involved:

- Infected host cells

- Cytotoxic T cells

- Helper T cell

The product:

- Target and kill infected host cells

Cell-Mediated Immunity: the fight against antigens inside our own cells

What cell type is necessary for both processes?

Helper T cells

Human Immunodeficiency Virus (HIV) infects Helper T cells

What happens when HIV infects helper T cells?

What happens when HIV infects helper T cells?

How could we prevent HIV infection from progressingto disease?

Vaccination!

What is a vaccine?

Attenuated whole-agent vaccines- weakened microbes (measles, mumps, rubella, chickenpox…)

Inactivated (killed) whole-agent vaccines- killed microbes (polio, rabies,pertussis)

Toxoids- inactivated toxins (tetanus, diptheria, pertussis)

Subunit vaccines- partial antigenic fragments of microbes (hepatitis B)

Conjugated vaccines- polysaccharides combined with proteins(H. influenza b)

Current vaccination schedule

Why not vaccinate?

-Complacency about disease

-Benefits of vaccination not immediately evident (adverse reactions are immediate)

-Media’s role

-Need to link tragic events (eg. autism) with cause

-Philosophical beliefs based on above-Vaccines don’t work.-Why vaccinate when the disease is so rare?-Vaccines cause secondary disease.

Vaccine success story- smallpox

-Caused by variola virus (major and minor)

-First disease for which immunitywas artificially induced

-Last case in 1977

Source: Centers for Disease Control and Prevention

-Measles caused by Rubeola virus

-Symptoms: fever, rash, conjunctivitis, pneumonia, encephalitis (permanent damage), death

-Pre-vaccine: 3-4 million cases annually, 450 deaths, 28,000 hospitalizations, 1,000 childrenwith chronic disabilities (US ONLY)

-Highly contagious: requires > 90% vaccinationcoverage in population

-Currently leading cause of death from a vaccine-preventable disease (In 2010, there were 139,300 measles deaths globally – nearly 380 deaths every day or 15 deaths every hour)http://www.who.int/mediacentre/factsheets/fs286/en/

Refusing vaccines- who suffers?

Vaccines… the bottom line

-Vaccines work!

A total 98.8% reduction in vaccine preventable diseases in the US since vaccination schedule was implemented.

-Exemptors of vaccines break down herd immunity and increaserisk of disease on a population level

-Vaccines will never be 100% effective or 100% safe

-It is a personal choice, but be aware that one’s choice affectsthe rest of the community

SO GO GET YOUR FLU SHOT!AND BE SAFE AND HAVE A VERY HAPPY HOLIDAY

SEASON!