Lecture 2 - Immunity Flashcards
No specific type of vaccines, just the methods of vaccination
Immunity
- The protection against infectious disease conferred either by the immune response generated by immunization or previous infection or by other nonimmunologic factors
- body’s ability to resist infection
Two Types of Immunity
- Non Specific (Innate)
- Specific (adaptive/acquired)
Innate Immunity:
Skin
- Mechanical barrier Effective because: - Largest - Skin is selectively permeable - Reproduces constantly - Produces sebum - pH of skin is acidic
Innate Immunity:
Mucous Membranes
- Cilia in respiratory tract
- pH of the stomach
- Lysosomes in tears
Innate Immunity:
Iron Binding Proteins
- Some bacteria require iron for growth
- Lacoferrin (example)
- You then starve the bacteria from iron
Innate Immunity:
Phagocytosis
- PMS, monocytes, and macrophages
- Act as a vacuum cleaner
Innate Immunity:
Complement (two things they do)
- Set of circulating proteins that do two main things:
1. Able to bind to antibodies, make the bacteria more opsonized for the immune system
2. Recognize certain sugars on the cell wall of bacteria, and form a pore, insides of bacteria leaks out and the bacteria dies.
Specific Immunity:
Two Subcategories
- Humoral
- Cell Mediated (CMI)
Specific Immunity:
Humoral
- Antibody
- Antigen
- Circulating antibodies in the blood
Opsonization
When complement binds to antibodies and makes the bacteria more appealing for the immune system
DIfference between Innate and Adaptive Immunity?
– Innate: protects against ANY invader, does not discriminate
– Adaptive: directed against one type of invader, dependant on past exposure
Where do immune cells come form?
- Bone marrow
B-cells
- Make antibodies
- After a signal is sent from T helper two cells
- 1 B-Ceel, one type of bacteria
Antibody
- Protein that binds specification to a substance (antigen)
- IGs
- Produced by B-cells upon stimulation from antigen presenting T-cells
- Recognize toxins, capsules, some viral proteins
Antigen
- Non self
- Protein, glycoprotein, lipoprotein, polysaccaride
Structures that can be antigenic in a bacteria?
- Something on the outside
Antibody Binding
- Arm can bind to antigen
- On arm could bind to one antigen on one cell, and another on another cells
- This starts clumping the antigens
Antibody composition
- Y part (where binding occurs)
- Bottom part (consistent)
Clumping
- Glutamate
- Means there is a positive reactions
Antobody
- Ig produced in response to stimulation by antigen and reacting specifically with it
- Distinguish “non self” from “Self”
- Constant and variable region
Classes of IG
- IgG
- IgD
- IgA
- IgM
- IgE
IgG
- Host defines
- Crosses the placenta and protects the new born
IgD
- Role is unknown
IgA
- host defence
- Found in secretions (tears saliva, milk ext
- Dimer
IgM
- Host defence
- Early immune response
- Pentamer
IgE
- Allergies (hypersensitivity)
- Defends against parasites
1st Immune Response
- Ab production triggered on first antigen introduction
- Latent period of several days
- Circulating antibody detectable after 5-10 days
- Antibody in serum is maximum at 21 days (titer), then starts to drop to low levels
2nd Immune Response
- Basis for Immunization
- Occurs when Ag (NOT Ab) is introduced 2nd, 3rd, 4th time
- Lag, rapid Ab increase (2-3 days)
- Slow decrease
- Booster injection maximize Ab levels
Antibody Detection:
Serology Reaction
- Detects presence of Ab in serum sample
- Antigen and antibody interact (agglutination)
- Antibody titration
- Detect unknown microorganisms using known antisera
Agglutination
When an antigen and antibody interact
CMI:
T-Cells
- NOT antibodies
- Helper, suppressive, cytotoxic (killer) generated from memory T- cells
- Exposure to antigen induces response form trained T-cells
CMI:
Essential for defence against intracellular organism, parasites, tumours, and other foreign cells
Disorders of Immunity:
Allergy and Hypersensitivity
- Over reaction to antigens in absence of true infection
- Anaphylaxis
Disorders of Immunity:
Auto-immune disease
- Immune system reacts to its own “self” antigens
- “auto antibodies”
- Type I diabetes, MS, Lupus
Disorders of Immunity:
Immunodeficiency states
- Inability to produce antibodies and more disfunction CMI
- Congenital, disease, AIDS
- HIV destroys T helper cells
Disorders of Immunity:
Graft rejection
- NORMAL immune reaction to non self
- Controlled by immune suppressive medication
Immunization
- Passive Immunization
- Active Immunization
Passive Immunization
– administration of pre-formed antibody against a specific microbial agent
– IgG animal origin: short lived, risk of hypersensitivity reaction
– IgG human origin: short lived, no risk of reaction
– Gamma globulin (IgG): pooled from large grouped of blood donors and has antibodies to many common infections
– Hyperimmune globulins (IgG): specific for a particular microbe
Active Immunization:
Stimulates immune system by administration of antigen.
LONGER LASTING
Active Immunization:
Live Attenuated Vaccines
– Sub-clinical or mild illness mimicking the disease
– Local (IgA) and humoral (IgG) immunity
– Rapid immunity development
– Serious illness in immuno-compromised individuals
Active Immunization:
Killed Vaccines
– Antigens without infectivity
– May require boosters
– Adjuvant with toxoids
– Polysaccharide vaccines can be conjugated to protein (see conjugate vaccines)
Active Immunization:
Recombinant Vaccines
– DNA recombinant technology
– Attenuates microorganism
– Hep B vaccine
Active Immunization:
Adsorbed Vaccines
NOTE THE “AD”
– Vaccine mixed with inorganic salt for slower adsorption and longer- lasting immunity
– Tetanus, diphtheria
Active Immunization:
Conjugate Vaccines
– Designed for poorly antigenic microorganisms
– Conjugate antigen of interest to immunogenic, non-toxic protein – Haemophilus influenzae type b
Active Immunization:
Combined Vaccines
– For ease of administration
Active Immunization:
Combined Active-Passive Immunization
– Immediate protection after possible exposure to microbe
– Hyperimmune Igs and vaccine injected at DIFFERENT sites – Tetanus, Rabies, Hep B
Types of Active Immunization
- Live attenuated vaccines
- Killed vaccines (sub-unit vaccines and toxoids)
- Recombinant vaccines
- Adsorbed vaccines
- Conjugate vaccines
- Combined vaccines
- Combined Active-Passive Immunization
Passive Immunization:
IgG animal origin
Short lived, risk of hypersensitivity reaction
Passive Immunization:
IgG human origin
Short lived, no risk of reaction
Passive Immunization: Gamma globulin (IgG)
Pooled from large grouped of blood donors and has antibodies to many common infections
Passive Immunization: Hyperimmune globulins (IgG)
Specific for a particular microbe
Why Passive Immunization?
- Faster acting
- Short lived
