Immunology & Immunizations Flashcards
Describe the lines of defense of the immune system
First: (innate) external skin/mucosal membranes
Second: (innate) antimicrobial proteins, phagocytes, other cells that inhibit spread of invaders & trigger inflammation
Third: adaptive immune system
Describe how the surface barriers protect us against microorganisms
- protective chemicals that inhibit/destroy
- mucus-coated cilia in the respiratory tract sweep microorganisms from lower respiratory passages
- organ surfaces participate
Describe the internal defenses of the immune system
cells and chemicals
- phagocytes
- NK cells
- inflammatory response (macrophages, mast cells, WBCs, chemicals)
- antimicrobial proteins (interferons)
- fever
Describe phagocytes
type of cell that engulfs and absorbs bacteria, small cells, particles
Describe macrophages
- develop from monocytes
- chief phagocytic cells of the immune system
- free macrophages wander through tissue space
- fixed macrophages are permanent residents of some organs
Describe neutrophils
become phagocytic upon encountering infectious material in tissues
Describe Natural Killer cells
- large granular lymphocytes
- 2 types of receptors (inhibitory recognize self, activating recognize stressed/infected cells)
what are the cardinal signs of acute inflammation
redness, heat, swelling, pain (sometimes impairment of function)
What are the inflammatory mediators
- histamine
- blood proteins
- kinins
- prostaglandins
- leukotrienes
- complement cells
(released by injured tissue, phagocytes, lymphocytes, basophils, mast cells)
Describe the vascular permeability step of the inflammatory process
inflammatory chemicals cause vasodilation resulting in hyperemia & increased permeability & edema of local capillaries that produces exudates (proteins, clotting factors, antibodies)
Describe how edema works in the inflammatory response
- results from surge of exudates
- moves foreign materials into lymphatic vessels
- delivers clotting proteins to form a scaffold for repair and isolate the area
Describe the main points of th einflammatory response
- triggered when body tissues are injured/infected
- prevents spread of damaging/infectious agents
- disposes of cell debris & pathogens
What are the 5 leukocytes
Granulocytes (PMNs)
- eosinophils
- neutrophils
- basophils
- lymphocytes
- monocytes
What are the 4 steps of phagocyte mobilization
- leukocytosis: release of neutrophils
- margination: neutrophils cling to capillary walls
- diapedesis: neutrophils pass through
- chemotaxis: inflammatory chemicals promote positive chemotaxis of neutrophils
What do complement proteins do
major mechanism for destroying foreign substances (viral infection)
- consist of 30+ blood proteins that circulate in an inactive form
describe an interferon
Function
- antiviral
- reduce inflammation
- activate macrophages & mobilize NK cells
Describe a fever
- systemic response to invading microorganisms
- leukocytes & macrophages exposed to foreign substances secrete pyrogens
- pyrogens increase the body’s thermostat
- high fevers can denature enzymes
- moderate fevers can increase metabolic rate/repair & sequester iron & zinc in the liver
Describe adaptive immunity
- specific, systemic, memory
- Humoral immunity: antibody mediated (B cells)
- cellular immunity: cell mediated (T cells)
Define an antigen
- toxin or foreign substance that induces an immune response & production of antibodies
- most are large, complex molecules not normally found in the body
Describe B and T lymphocytes
cells of the adaptive immune system
- B (humoral): responsible for creation of antibodies once an antigen provokes a humoral response, mature in red bone marrow
- T (cell-mediated): proliferate & differentiate into effector cells of immunity & helper cells for antibody response by secreting cytokines, mature in thymus, mature = immunocompetence & self-tolerance
recognize and bind to antigens, communicate with each other to mount a specific immune response to destroy non-self substances
Describe a primary immune response
- occurs on first exposure to an antigen
- lag period of 3-6 days
- peak levels of plasma Ab reached in 10 days
- Ab levels slowly decline
Describe a secondary immune response
- occurs on re-exposure to an Ag
- sensitized memory cells respond within hours
- Ab levels peak in 2-3 days at much higher levels than primary response
- Abs bind with greater affinity
- Ab level can remain high for weeks/months
Describe active humoral immunity
When B cells encounter Ags & produce specific Abs against them
Two types
- Naturally acquired: response to bacterial/viral infection
- Artificially acquired: response to a vaccine of dead/attenuated pathogens
Describe vaccines roles in active humoral immunity
- spare us the sxs of a primary response
- provide Ag determinants that are immunogenic and reactive
- target only one type of helper T cell so they don’t fully establish cellular immunological memory
Describe passive humoral immunity
**B cells not challenged by Abs & immunological memory not occurring*
Two types
- naturally acquired: Abs delivered to fetus via placenta or infant through milk
- artificially acquired: injection of serum such as gamma globulin which provides immediate protection but ends when Abs naturally degrade in the body
Flip this card for a nice lil reminder on active vs passive humoral immunity
Describe antibodies
- immunoglobulins (gamma globulin portion of blood)
- proteins secreted by plasma cells
- capable of binding specifically with Ag detected by B cells
Describe the cell-mediated immune response
- T cells provide defense against intracellular Ags
- Types of T cells: Helper T (TH), Cytotoxic T (TC)
- Others (Regulatory T cells - TREG, memory T cells)
Describe the difference between humoral and cell-mediated immune responses
HUMORAL
- B cells produce Abs as a simple form of ammunition
- targets: bacterial, molecules in extracellular fluid
CELL-MEDIATED
- T cells recognize & respond to processed fragments of Ags displaced on surface of body cells
- targets: infected body cells, abnormal/cancerous cells, cells of infused/transplanted foreign tissue
Describe the role of helper T cells
- central role in adaptive immune response
- help activate and induce T & B cell proliferation
- activate macrophages & recruitment o fother immune cells
without TH there is no immune response
Describe the role of cytotoxic T cells
directly attack & kill other cells
activated Tc cells circulate in blood & lymph in search of body cells displaying the Ag they recognize
Targets:
- virus-infected cells
- cells with intracellular bacteria/parasites
- cancer cells
- foreign cells
What are the 2 types of immunization processes
active vs passive
Describe the active immunization process
- used to simulate the body’s natural defense mechanisms
- contains non-infectious fragments of bacteria/virus OR a toxin produced by that organism that has been modified to a toxoid
immune system responds by producing Abs and other protective substances
Describe the immune response to an active immunization process
produces a primary immune response through…
- B cell proliferation
- Ab response
- T-cell sensitization
Subsequent exposure results in a secondary response (increased proliferation of B cells & formation of Abs, protects person from developing disease)
may require boosters to sustain protection
Describe live-attenuated active vaccines
- live microbes that are weakened
- elicit strong cellular & Ab response often conferring lifelong immunity with 1-2 doses
- contraindicated in those with compromised immune systems
Ex. polio, measles, yellow fever, flumist, zoster
List the types of active vaccines
- live-attenuated
- inactivated
- subunit/recombinant
- conjugate
- toxoid
- mRNA
- recombinant vector
Describe inactivated active vaccines
- killing the disease-causing microbe with chemicals, heat, radiation
- more stable/safer than live vaccines (dead microbe can’t mutate back to disease-causing state)
- weaker than live vaccines therefore require more in a series or boosters
Ex. IPV, Hep A, rabies
Describe Subunit/Recombinant active vaccines
- contain only the Ag parts of the pathogen
- difficult & expensive to create
Ex. Flu shot, pertussis, HPV, Hep B
Describe conjugate active vaccines
Made using pieces from the coats of bacteria plus a carrier protein
Ex. pneumococcal
Describe toxoid vaccines
- protein-based toxin rendered harmless (toxoid) & used as the Ag in the vaccine to elicit immunity
- used for bacteria specifically
- may require several doses
Ex. diphtheria, tetanus
Describe mRNA active vaccines
work by teaching our cells to make a harmless piece of a spike protein which is found on the surface of viruses
Ex. COVID
Describe recombinant vector active vaccines
use an attenuated virus or bacterium to introduce microbial DNA to cells of the body (still in development)
Describe the passive immunization process
Abs against a specific infectious organism given directly rather than the body creating them
Sources of Abs
- animal serum from immune source
- pooled human immune globulin
- hyperimmune globulin from people known to have Abs to a specific disease
- Ab-producing cells grown in a lab
Describe the uses for passive immunization
- inadequate immune responses
- infection prior to vaccination
- to prevent disease when people are likely to get exposed prior to completing a vaccine series
- occasionally used for healthcare workers, pregnant women, international travelers
(passive immunization lasts only for a few days/weeks until the body eliminates the injected Abs)
Ex. Hep A&B, tetanus, varicella
Describe the absolute contraindications to vaccines
- serious allergic reaction to a vaccine or one of its components
- live vaccines should not be used in those with: weakened immune system/immunosuppressed, pregnancy, some neuro disorders like guillain barre
- individual per vaccine
Describe some of the relative contraindications to vaccines
- recurrent/mild illness
- current/recent abx use
- previous mild/moderate local tenderness, redness, swelling, fever after any vaccine
- previous hx of allergy to specific vaccine contents
- fam hx of adverse reactions to immunizations
What are the things reported in adverse event reporting
to the US DHHS
- anaphylaxis/anaphylactic shock within 7 days of a vaccine
- encephalopathy, encephalitis, seizures
- any sequelae
- serious/unusual events
- side effects listed as contraindications to future vaccination on the package insert
Describe herd immunity
What diseases does strep pneumoniae cause
- pneumonia
- otitis media
- meningitis
- bacteremia in peds, elderly, immunocompromised
leading infectious cause of pneumonia related death in kids worldwide
- rise in resistant pneumococcal strains = urgent need for vaccination
What are the immunologic considerations of haemophilus influenzae B
- gram neg anaerobe
- opportunistic pathogen (lives in host without causing disease until the right opportunity
- decreased vaccine rates have led to an increase in pneumonia, meningitis, and epiglottitis
What are the immunologic considerations for pertussis
aka whooping cough
- highly contagious respiratory disease
- caused by bordatella pertussis
- uncontrollable, violent barking cough
- molecular changes to b. pertussis as well as new vaccine mechanism contributing to resurgence/less protective time
- given in Tdap/Dtap vaccine (diphtheria, tetanus, & pertussis)
What are the immunologic considerations for Tetanus
- clostridium tetani
- found in soil, dust, manure, enter through breaks in skin
- uncommon in the US
- sxs: jaw cramping, sudden involuntary muscle spasm, GI issues, trouble swallowing, seizures, severe HA, fever, sweating, unstable BP and HR
What are the immunologic considerations for diphtheria
- caused by cornybacterium diphtheriae
- person to person spread (respiratory droplets)
- thick covering in back of throat leading to difficulty breathing, heart failure, paralysis, death
What are the immunologic considerations for meningiococcemia
- neisseria meningitides
- responsible for bacterial meningitis & sepsis
- spread person to person through droplets
- vaccination rates reduced disease and epidemics worldwide
Describe the immunologic considerations for diarrhea
- multiple etiologies: rotavirus, shigella, enterotoxogenics, e coli, campylobacter, etc
- spread through water, food, utensils, hands, flies
- death d/t dehydration, electrolyte imbalance
Describe the immunologic considerations for rotavirus
- most common cause of severe diarrheal disease in young children
- 2 oral, live, attenuated vaccines available internationally (safe & effective, must be given before 8 months old)
What are the immunologic considerations for measles
- viral
- isolated & extracted measles strain from a sick person’s blood in the 1950s to create the first vaccine in the 1960s: Edmonston-B
- once dose of measles vaccine is 93% effective in preventing if exposed, 2 doses are 97% effective
What are the considerations for immunizations in pregnancy
- protect both mother and baby
- can provide passive protection against infections acquired independently after birth
- ideally immunized before conception but can be given during pregnancy especially if: high risk exposure, tarotogenic infection, immunizating agent unlikely to cause harm, effectiveness
