Equine Immunology Exam 1 Flashcards
Exam 1
What is the immune system used for?
fighting off infections
The immune system is a _________ system that is very _______ tuned
complicated; fine
What are the physical barriers of the immune system?
skin and mucous membranes
What is the largest organ in the body?
skin
What does an invasion/infection have to pass through first?
the physical barriers
What is the order of events when an infection enters the body?
- must pass through the physical barriers
- innate immunity
- inflammation
- adaptive immunity
Pathogens
disease causing organisms (bacteria, virus, fungus, worms, etc.)
What are the topics of barriers of the immune system?
-mechanical
-chemical
-reflexes
What are the innate topics of the immune system?
-phagocytosis
-protective proteins-cytokines
-fever
-NK cells
-inflammation
What are the adaptive topics of the immune system?
-cell-mediated
-humoral
Immunity
a state of having sufficient biological defenses to avoid infection, disease, or other unwanted biological invasion
Natural acquired immunity
infection
-the body developed antibodies after having a disease
Artificial acquired immunity
vaccination
-the vaccination builds the antibodies (sometimes you get sick, sometimes you do not)
Passive acquired immunity
colostrum/plasma/anti-serum
-foals must nurse colostrum to get antibodies from the mare
Antigen
any substance capable of generating an immune response
-proteins or parts of bacteria, viruses, and other microorganisms
-can also be “self-antigens” (some people have more than others)
Self-tolerance
the capability of the body to tolerate itself
-auto-immune disease occur when self-tolerance is lost or low
Host
an organism that harbors a virus, bacteria, or parasites
Antibody-protein
produced by blood cells of the host to bind to antigen
Leukocytes
cells of the immune system, also called white blood cells
Mechanical barriers
-epidermis
-goblet cells
-saliva
-coughing, sneezing
-flushing action of urine/tears
-cilia (lungs, intestines)
Epidermis
skin-continuous layer of tightly packed sheets (the wall between the outside and inside)
Goblet cells
specialized epithelial cells in the GI tract that produce mucus, preventing microbes from gaining access to the body (in the GI tract)
Saliva
dilutes microbes
Coughing, sneezing
mechanically expels pathogens from respiratory tract (less stays in)
Flushing action of urine/tears
expels pathogens
Cilia
in the lungs and intestines, movement of mucus removes microorganisms
Chemical barriers
-sebum
-skin acidity
-the B-defensins (lysozymes, etc.)
-gastric juice
Sebum
produced by sebaceous glands (in skin and hair), can inhibit some microbe growth
Skin acidity
pH~5.4
-prevents a lot of microorganisms from surviving on the skin
B-defensins (lysozymes)
enzymes in sweat, saliva, tears, and breast milk that break down bacteria cell walls
Gastric juice
pH~1.3-3.0
-produced by stomach glands, destroys most (not all) bacteria and viruses
Commensal microflora
urinary and gastrointestinal tracts and skin serve as biological barriers by competing with pathogenic bacteria for food and space (no space for bad bacteris)
Innate immune response
-first line of defense
-built-in immunity to resist infection
-natural, native immunity
-present from birth
-not specific for any particular microbial substance
-not enhanced by second exposure
-has NO memory
Innate immune response function
-slows the growth of infection agents until the adaptive immune response kicks in
-must focus on the BROAD characteristics of microbes (microbes evolve rapidly)
-PAMPs
-activates the adaptive immune response
How long does it take for the body to create an immunity of a new disease?
minimum of 2 weeks
PAMPs
-pathogen-associated molecular patterns
-structural elements that are common to broad classes of microbes and are common to many different microbes
What do PAMPs bind to?
PRRs (pattern recognition receptors)
PRRs
pattern recognition receptors
-what PAMPs bind to
-on immune cells of the innate immune system
-phagocytes (neutrophils, macrophages, dendritic cells)
-phagocytosis
Phagocytosis
when cells engulf other cells
Recognition of microorganisms by phagocytes:
-many receptors on neutrophils and macrophages bind to microorganisms
-specialized recognition of classes of molecules and structures not present in or on self tissues
-selective specificity for microbial patterns
Process of phagocytosis:
- phagocyte membrane zips around the microorganism (engulfs it)
- microorganism is internalized in a phagosome
- phagosome fuses with lysosomes (break down cells that leads to death)
- lysosomal enzymes indirectly kill phagocytosed microbes by making reactive oxygen species and nitric oxcide
Free radical
oxygen binding to anything it can find
How many things does O-2 need to bind to?
2 things
How many things does H+1 need to bind to?
one thing
Hydrogen peroxide
H2O2
-unstable
-extra oxygen kills when it bursts
ROS
reactive oxygen species
Stages of antigen processing
- uptake
- degradation
- antigen presentation (transport and expression of antigen proteins on the surface of cells for recognition by T cells)
Neutrophil function
-get to the site of infection rapidly and ingest microorganisms (slows down infection
-kills microbes by engulfing them via phagocytosis
-kill by using reactive oxygen species
What happens after neutrophils take up microorganisms?
they will die
What forms from dead neutrophils and microbes?
pus
Neutrophils
(aka polymorphonuclear leukocytes)
-most abundant immune cell in the blood
Monocytes
migrate into the tissues and differentiate into macrophages
Monocyte function
-can uptake organisms many times without dying immediately
-phagocytosis of microorganisms
-present antigens to T cells
Cells involved in innate immunity
-neutrophils (PMN)
-monocytes (macrophages)
-eosinophil
-basophil
-mast cell
Eosinophil cells
-anti-parasite
-allergy immunity
-contains granules with histamine
-removal sites
Basophil cells
-protection of mucosal surfaces
-allergy immunity
-contains granules with histamine
-removal site
Mast cell
-protection of mucosal surfaces
-allergy immunity
-contains granules with histamine
-removal site
What is the link between the innate and the adaptive immune system?
antigen presenting cells (APCs) or phagocytes
Antigen presenting cells
-dendritic cell, macrophages
-the link between the innate and adaptive immune systems
-found in tissues, skin, nose, lungs, stomach, and intestines
Process of APCs linking the immune and adaptive immune systems:
once they have engulfed the antigen (bacteria) at the site of the infection they leave the tissue and enter the lymphatic system to travel to lymph nodes to present antigen to lymphocytes (adaptive immune system)
General scheme of immune response:
- pathogen damages the epithelium to break through the epithelial barrier
- epithelial cells ‘activated; upon contact with microorganism (start to signal the immune system)
- chemokines and cytokines are made by activated epithelial cells
- recruits innate immune cells (neutrophils)
This all happens within seconds
Chemokines and cytokines
-proteins that allow cells to communicate with each other
-cause cells to migrate from the blood into the tissue underlying the infection
Cytokines role in inflammation
change the morphology, adhesive properties and permeability of endothelial cells
Steps of infammation:
- cytokines change the endothelial cells
- vasodilation/leaking of fluids
Heat
caused from more blood in the area
Swelling
happens because the liquid leaks to the extravascular space
Redness
because there is more blood in the area
Pain
messengers are signaled to the brain, a pain response is sent back
Loss of function
inflamed area is not working the right way (not always lameness)
What is the layout of post capillary endothelial cells?
they are impermeable to cells and plasma
-cells are tightly packed in blood vessels
What are the 5 signs of inflammation?
-heat
-swelling
-redness
-pain
-loss of function
When might pus occur?
when phagocytic cells respond to cytokines and chemokines and when cells migrate from the blood into the tissue underlying the infection
Steps of the protective and innate immune system (7)
- bacteria breaks skin barrier
- activates epithelial cells
- cytokines and chemokines are produced
- inflammation (vasodilation) and attracts phagocytes
- Inflammation (leaky vessels)
- allows phagocytes to leave the blood and go to tissue site of infection
- phagocytes kill bacteria
Lymphoid organs
sites of generation, maturation, and initiation of adaptive immune responses
Central lymphoid organs
-form antibodies and particular WBCs
-Thymus (T-cells mature) - lies behind the heart and slowly disappears with age
-Bone marrow (B-cells mature)
Peripheral lymphoid organs
(B and T cells Live)
-lymph nodes
-spleen white pulp
-mucosal-associated lymphoid tissue
Lymphatics functions:
-removal of excess fluid (homeostasis)
-waste material transport
-filtration/movement of lymph (information to lymph nodes)
-transport (immune cells circulate)
Adaptive immunity
-immunity established to adapt to infection
-learnt by experience
-confers pathogen-specific immunity
-enhanced by second exposure
-has memory (remembers and stores a few cells that have encountered a microbe/bacteria before)
-is poorly effective without innate immunity
Vaccination needing 1 vaccination for life:
adaptive immune system has good memory for this disease (ex. chicken pox)
Vaccination needing regularly vaccinated:
adaptive immune system has poor memory for this (ex. flu, rabies, tetanus)
What are the 2 parts of the adaptive immune system?
-cell mediated immunity (CMI)
-humoral immunity
Cell mediated immunity (CMI)
T cells
-from bone marrow, mature in thymus
-produce cytokines
-activate more microphages to perform killing of pathogens
-activate B cells to produce antibodies
-cytotoxic T cells kill infected cells
-limits infection but does not prevent it.
Humoral immunity
B-cells
-from bone marrow and mature in bone marrow
-antibody production
-go to lymphoid tissue where they proliferate and make daughter cells
-antibodies are able to prevent infection (right location and right concentrate)
Types of antibodies made by B-cells:
-IgM
-IgG
-IgA
-IgE
IgM antibody
early antibody
-agglutination
IgG antibody
multifunctional
-opsonization
-complement fixation
-IgG(A), IgG(B), IgG(C), IgG(T)
IgA antibody
mucosal surfaces
-neutralization (of toxins and viruses)
IgE antibody
mediates allergic responses
-bound to cells (mast cells, eosinophils, basophils)
Pathogens can __________
mutate; the body cannot always protect against mutation
-some viruses mutate more than others
What viruses mutate more often?
-flu
-lepto
-salmonella
What viruses don’t mutate as often?
tetanus
Why do we vaccinate?
- to aid in prevention of disease
- to reduce severity of disease
- to minimize spread of disease
Primary vaccination
to establish antigen-specific memory
Revaccinaton
to prevent antibody or CMI from decaying, to Boost/wake-up the adaptive immune system
At what level do antibodies need to be maintained?
-high level
-do not wait till it falls to a low level
Factors affecting immune response:
-age
-genetics/breed
-antigen exposure
-lifestyle
-stress
-exercise
-nutrition
-gut microflora
-endocrine
Immune under-reactions
-cancer (hepatitis, HIV, shingles, TB)
-infection (viruses, bacteria, fungi, parasites)
Immune over-reaction
-autoimmune problem (type 1 diabetes, rheumatoid arthritis, psoriasis, multiple sclerosis, lupus, inflammatory bowel disease)
-allergic reaction (hay fever, eczema, asthmas, sinusitis)
Internal immune threats
-autoimmune problem
-cancer
External immune threats
-allergic reaction
-infection
