Immunity Flashcards
What are the forms of Immunity?
Innate: non specific, present at birth
Acquired: after birth
What is Active vs Passive Immunity?
Active: antibodies develop after antigen exposure (make antibodies)
- Natural acquired: through environmental
exposure to pathogens
- Induced: Through vaccines that have pathogens
Passive: antibodies from another source (receive antibodies)
- Natural acquired: through mother
- Induced: Injection of antibodies
What are the two categories of defense?
Nonspecific: Against any type of invading agent = innate
Specific: protect against specific pathogens
What is an antigen?
Antigen: substances recognized as foreign and provoking immune response
What are the levels of immune defense in response to pathogens
First line: Nonspecific - Skin (mechanical, chemical, reflexes)
Second line: Nonspecific - Blood (fever, inflammation)
Third line: Specific Immunity (Cell-mediated)
LIFE!
Name all Non-specific / Innate Defenses
- Physical Barriers
- Phagocytes
- Immunological Surveillance
- Interferons
- Complement / “C” proteins
- Inflammation
- Fever
What happens in the Physical Defense -Physical Barriers (nonspecific, 1st line)
Physical Barriers = Keep hazardous material outside body
- Epidermis: closely packed, keratinized cells
- Mucous membrane: Mucous traps microbes and foreign substances
- Nose Hairs: trap and filter
- Cilia: upper respiratory tract propel trapped particles up and out = beat rhythmically
- Fluids:
- Lacrimal apparatus of eye = Washing action of
tears
- Lysozymes break down cell walls - present
in saliva, perspiration, nasal secretion, and tissue fluid
- Saliva washes mouth
- Urine cleanses urinary system
- Vaginal Secretions, defecation, vomiting
What happens in the Physical Defense - Chemicals (nonspecific -1st line)?
- Sebaceous (oil) glands secrete sebum (protective film)
- Perspiration, gastric juice = very acidic (1.5-2 pH), vaginal secretions - all acidic
What happens in Phagocytes (nonspecific - 2nd line)
Phagocytes = Attack and remove dangerous microorganisms
ACTIVE TRANSPORT
Microphages
- Neutrophils and Eosinophils
- Leave the bloodstream
Macrophages (monocytes mature to macrophages)
- Engulf pathogen, destroy it with lysosomal enzymes
- Bind to pathogens, other cells can destroy it (flag)
- Destroy pathogens, release toxic chemicals into interstitial fluid
2 types
- Fixed Macrophages = Stay in specific tissues/organs
- Microglia: found in CNS
- Kupffer Cells: found in liver sinusoids
- Free macrophages = Travel throughout body
What happens in Immunological Surveillance (nonspecific - 2nd line) ?
Surveillance: Constantly monitors normal tissues
- Carries out by natural killer cells (NK) cells
- Identify and attach to abnormal cells
- Golgi apparatus in NK cells form perform vesicles
-> Vesicles release perforins (exocytosis)
-> Perforins lyse abnormal plasma membrane
What happens in Interferons (nonspecific - 2nd line)
Interferons = proteins made and released by lymphocytes
- proteins = type of cytokine = chemical messenger
- Cytokine = produced by macrophages, dendritic cells, NK cells, and cells of adaptive immunity
- > Produced in response to infection with intracellular agents (viruses or intracellular bacteria)
What happens in Complement “C” proteins (nonspecific - 2nd line)
C proteins = complement the action of antibodies
- attacks and lyses, attracts phagocytes, enhance inflammation (attack and destroys pathogens)
What happens in Inflammation (nonspecific - 2nd line)
Inflammation = Triggers a complex inflammatory response
- attempts to dispose of micrones, prevent spread and prepare sity for tissue response
3 stages
- Vasodilation & increased blood vessel permeability. Feel pain that area
- Emigration of phagocytes from the blood into the interstitial space and then to site of damage
- Tissue repair
What happens with Fevers (nonspecific - 2nd line)
Fever = High body temperature
Pyrogens = fever inducing substances = cause hypothalamus to raise the body temp (to kill pathogen)
what are the 4 properties of immunity (3rd line)?
- Specificity = each T or B cells responds only to specific antigen and ignores other
- Versatility = body produces many types of lymphocytes = fights different type of antigens
- Memory = active lymphocytes ( memory cells) stay in circulation. = provide immunity against new exposure
- Tolerance = Immune system ignores “normal” (self) antigens
T Cells
Provide cell-mediated immunity = respond primarily to cells infected with intracellular pathogens = viruses and intracellular bacteria, cancer cells, and foreign cells such as those from a transplanted organ
Cytotoxic T Cells
seek out and destroy abnormal and infected target cells = cells may use perforin = poke holes into cells/pathogens and then destroy them, secrete toxic lymphotoxin or active genes that will tell cell to die
- Kill like natural killers.
- T cells have specific receptor for particular microbe
- NK cells destroy a wide variety of microbe-infected cells.
Helper T Cells
activate antibody and cell mediated immune responses.
- Have no cytotoxic or phagocytic activity
- Cannot kill infected host cells or pathogens
- Essential for the production of antibodies
- Important in the activation and growth of cytotoxic T Cells
- Maximize activity of phagocytes.
Suppressor T Cells
deactivate T cells and B cells when needed = prevent the immune response from becoming too intense
B Cells
Provide antibody-mediated immunity = Defend against antigens and pathogens in body fluids.
- Made in Bone Marrows
B-Cell Activation: Need Helper T-Cell
B-Cell Division: Activated B Cell Divides into plasma cells and memory B Cells
Plasma Cells = Synthesize and secrete antibodies into interstitial fluid
Memory B-Cells = remain in reserve to respond to next infection
Things to note about Antibodies
Antibodies are Y shaped
Antibodies can only “see” extracellular pathogens. 2 types of immunity work together
STEP 1: Antigen presentation
Cell mediated immunity cannot get started without the aid of the nonspecific phagocytosis
- The phagocytic cells that initiate the process are called antigen presenting cells. First step is antigen presentation
- Any cell can present antigens, except RBCs. Due to lysosomes
Types of Antigen Presenting Cells (APC)
- Free and Fixed macrophages
- Kupffer cells - Liver
- Microglia - In the CNS
- Dendritic cells = present in those tissues that are in contact with the external environment = in lungs
- Langerhans cells - considered a type of dendritic cell in the skin
Step 2: Recognition
APC engilts the antigen -> Enzymes inside the APC break down the antigen into smaller particles
The processed antigens are transported to the surface of the APC
The T-cell receptor recognize these and binds to them
Step 3: Co-Stimulation
Macrophage and the T Cell interact -> release cytokines = chemicals that evoke a localized response
- Increased phagocytic activity = more macrophages and neutrophiles enter the tissues
- T Cell production. Also Helper T Cells
- T Cell differentiation
- And more cytokine secretion = poke holes into invader
Step 4: LAST
Destruction of infector
Autoimmune Disorders
Malfunction of system that recognizes and ignores “normal: antigens = make autoantibodies against body cells
- Rheumatoid arthritis = inflammatory diesase, Insulin-dependent diabetes mellitus (IDDM)
Immunodeficiency Disease
Failure of immune system
- HIV, developmental problems during fetal stages or childhood, radiation
Allergies
Inappropriate or excessive immune response to antigens
HIV Virus
HIV damages mainly Helper T-Cells
- Viruses bud rapidly from infected cell membrane - Cell lysis
- Body attacks the infected cells - Kills cells NOT viruses
- Body’s ability to replace helper T Cells decline
