(I) Lecture 1: Introduction to Immunology Flashcards
Pathogens
- bacteria
- viruses
- fungi
- p;arasites
T or F
Microbes are everywhere. Most of them cause disease
False
Microbes are everywhere. Most of them are innocuous (minority cause disease)
T or F
Adaptive immunity is the first to act in response to pathogenic microbes
False
Innate immunity is the first to act in response to pathogenic microroganism
What is our first line of defense against microbes?
Physical barriers (like skin and epithelia) are our first line of defense against microbes
T or F
All immune cells (phagocytes and lymphocytes) derive from a lymphoid progenitor?
Fales immune cells derive from both mylenoid progenitors (phagocytes) and lymphoid progenitors (lymphocytes
T or F
Our microbiome can protect us against infection from pathogenic microbes
True
What happens when the physical barriers are compromised?
Immune cells come to the rescue (monocytes, macrophages, neutrophils and dendritic cells)
How do cells communicate?
Through chemical signaling (cytokines and chemokines)
How is passive immunity achieved?
By acquiring immune cells/proteins from others
Can be natural (maternal) or artificial (from donors/transplants)
Where are parasites prevalent?
In tropical areas
Infectious Diseases
Caused by pathogenic microorganisms like bacteria, viruses, parasites or fungi
Can spread from environment or from person to another
Modes of Transmission of Diseases
Direct contact (skin-to-skin contact, kissing, sex)
Droplet spread (sneezing, coughing and talking)
Indirect
- airborne (dust or droplets suspended in air)
- vehicleborne (food, water, blood and fomites)
- vectorborne (mosquitoes, fleas and ticks)
Examples of infectious diseases
- respiratory infections and TB
- enteric infections
- malaria and neglected tropical diseases
- HIV/AIDS and STIs
Burden of Infectious Diseases
Burden of disease is closely related to GDP
Richer country (higher GDP) = lower burden
and vice versa
How has life expectancy improved over the years?
By controlling infectious diseases
Chain of infection
- Pathogen (bacteria, virus, fungi, parasite)
- Reservoir - where pathogen is found (people, animals, soil, food, water)
- Portal of Exit - reservoir to host (coughing/sneezing, bodily secretions, feces)
- Mode of Transmission (direct contact, indirect contact, vectors)
- Portal of Entry (mouth, nose, eyes, cuts in skin)
- Susceptible host (elderly, infants, immunocompromised, anyone)
Prevention and Control of Infectious Diseases
- vaccines
- safe food handling (foodborne pathogens)
- good hygiene (washing hands, covering mouth to sneeze/cough)
- water treatment and purification (waterborne disease)
- sewage disposal (enteric pathogens)
- condom during sex (STD)
- reduced reservoir for infectious vectors like mosquitoes (malaria –> eliminate mosquitoes)
Endemic
Present ALL the time at EXPECTED levels in a population within a region
Can have fluctuations
ex. flu, common cold, malaria, Lyme disease
Epidemic
Sudden rise in the number of cases ABOVE the normal endemic level of the region
Outbreak
Sudden rise in the number of cases in a SMALLER community (daycare, hospital, nursing home)
Pandemic
An epidemic on a GLOBAL scale
widespread over several regions, countries or continents
What does our immune system do?
Barriers – keep pathogens from entering tissues
Cells – detects and destroys the invading cells
Cytokines/chemokines – passes message along to other cells
Memory – quickly responds to the pathogen and prepares for next time
Main Immune Defenses
Anatomical barriers, Immune Cells, and Proteins
Anatomical Barriers
Skin, Tissues and Commensal Microbiota
Microbiota
Environmental factors (diet, maternal) and genetics help shape the microbiome (all microbes in the body)
Huge diversity, varies by location in the body
Immune cells
White blood cells (leukocytes)
- Phagocytes and lymphocytes
Found in buffy coat of blood
Derived via hematopoiesis
Blood
55% of total blood is plasma (blood hormones, clotting factors, proteins, enzymes and antibodies)
Buffy coat (<1%) has leukocytes (WBCs) and platelets
The remaining 45% contains erythrocytes (RBCs)
How are blood cells derived?
All blood cells, including immune cells, are derived via hematopoiesis
Phagocytes
Type of immune cell
From myloid progenitors
Ex. monocytes, macrophages, neutrophils, dendritic cells
Lymphocytes
Type of immune cell
From lymphoid progenitors
Ex. T cells, B cells, NK cells
Neutrophil
uses chemical signaling to engulf bacteria
Macrophage
detects IgG to know what cells to phacytose
Proteins
secreted by cells
Ex. cytokines, complement proteins, antibodies
Innate Immunity
happens FIRST
Through barriers, cells, and immune signaling
Adaptive Immunity
creates memory
T-cell and B-cell immunity
Types of Immunity
Active immunity
Passive immunity
Passive Humoral Immunity
Acquired Immunity
Immunity that develops during your lifetime
Active Immunity
OWN BODY’s immune response is activated
Natural: antibodies develop in response to an infection
Artificial: antibodies develop in response to a vaccination
Passive Immunity
Immune components are ACQUIRED from someone or somewhere else
Natural: antibodies received from MOTHER (pregnancy + breastmilk)
Artificial: antibodies received from a MEDICINE (ex. gamma globulin injection)
Passive Humoral Immunity
Provided by the transfer of antibodies from a donor
IMMEDIATE, SHORT-TERM immunity (months)
Natural Passive Immunity
During PREGNANCY, antibodies are transferred from mother to fetus
Vaccination during pregnancy also transfers protection to baby (ex. Tdap vaccine for tetanus, pertussis - whooping cough)
After birth, antibodies are transferred from mum to baby via breastmilk
Immune System Development
Microbiome of a newborn is affected by the mother’s and the mode of delivery (natural vs C-section)
- it is shaped through infancy
Newborns have INNATE immunity but NO adaptive immunity until 1 year of age
Artificial Passive Immunity
Intravenous Immunoglobulin (IVIG)
- Therapy treatment for patients w/ antibody deficiencies
- Prepared from a pool of immunoglobulins (antibodies) from the plasma of thousands of healthy donors
