Immunity

Adapted from Adlai E. Stevenson High School

Primary Function of the Immune System

Provides protection against disruption by pathogens or toxins

Helps discriminate between “self” and “nonself” Pathogen - Definition:

– Any disease causing agent (microorganisms) Types:

– Bacteria– Viruses– Parasites– Fungi

The DefensesNon-Specific

Definition:– Agents do not have to recognize a foreign

invader to fight it (work by preventing pathogen from entering the body)

Examples:– Skin– Tears– Saliva– Sweat – Mucus– Macrophage

The DefensesSpecific Definition:

– Agents attacks only certain invaders, specialized defense

Types of Cells– Helper T cells

• 1st line of specific defense• Help recruit other immune cells & tell them to

attack certain invaders

– Killer T cells• Can distinguish virus infected cells from

uninfected cells by the unique molecular signals on the infected cells surface

– B cells• Told by helper T cells to make antibodies to

prevent specific antigens from hurting the body…. “Memory”

Lymphocyte Function

T cell response– Attach to foreign

antigen bearing cells and interact directly

Cell Mediated Immunity

Humoral

Immunity B cell response

– Differentiate into plasma cells

– Produce antibodies

Antibodies & Antigens Proteins Can recognize

chemical signals from another cell (pathogen)

“Self” Y shape

Chemical signal on the surface of a pathogen

Cell Mediated Immunity

Cytotoxic T cells

Killer T cells recognize body cells infected with a virus; then destroy those cells by drilling holes in their plasma membranes.

Cell or Antibody Mediated Immunity

Helper T cells

Helper T cells start the immune response by activating B or T cells.

Macrophage Antigen-presenting cell

Helper T cell

Antigen-presenting cell APCB cell

suppressorT cell

cytotoxicT cell

T cells and cell-mediated immunity

Antibody Mediated Immunity

B cells– Activated when it

encounters an antigen that fits its antigen receptor

– Proliferates (colonial expansion)

• Plasma cells-->antibodies

• Memory cells-->future fights

Vaccines What is in the shot they give you?

– Dead or inactive (attenuated) pathogens How does it work?

– Cause B cells to make antibodies against the foreign antigen

The Memory of Infection

Autoimmune Disorders “Auto” = self Definition: a disease in

which the immune system attacks the tissue of the body; cause is generally unknown

Immune system distinguishes “self” from “non-self

Examples: – multiple sclerosis (MS) - T

cells destroy myelin sheath around neurons

Cold Virus, Rubella, & Strep Common Cold Virus

– Influenza; contagious viral infection of the nose, throat and lungs which often occurs in the winter.

Rubella virus– German measles

Streptococcus bacterium– Strep throat is an

infection of the pharynx caused by streptococcus bacteria.

Treatments:– Strep Throat

• Antibiotics such as penicillin or erythromycin

– Rubella• Vaccine

– Influenza