Fire Ant Stings and Other Mishaps: Immnology
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Transcript Fire Ant Stings and Other Mishaps: Immnology
Fire Ant Stings and Other Mishaps:
Immnology
Donna Sullivan, PhD
Host Defensive Systems
1st line of defense intact skin
mucous membranes and their secretions
2nd line of defense phagocytic white blood cells
inflammation
-complement
fever
-interferon
3rd line of defense B and T lymphocytes
antibodies
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nonspecific
specific
Physical or anatomical barriers
Outermost layer of skin is composed of epithelial cells
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compacted, cemented together and impregnated with
keratin
Flushing effect of sweat glands
Damaged cells are rapidly replaced
Mucous coat impedes attachment and entry of bacteria
Blinking and tear production
Stomach acid
Nasal hair traps larger particles
Chemical Defenses
Sebaceous secretions
Lysozyme, an enzyme that hydrolyzes
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the cell wall of bacteria, in tears
High lactic acid and electrolyte
concentration in sweat
Skin’s acidic pH
Hydrochloric acid in stomach
Digestive juices and bile of intestines
Semen contains antimicrobial
chemical
Vagina has acidic pH
DIFFERENTIATION OF CELLS
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Leucocytes
Granulated: granules, lobed nuclei
Neutrophils
Eosinophils
Basophils
Agranulated: un-lobed, round nuclei
Monocytes
Macrophages, dendritic cells
Lymphocytes
T cells, B cells
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GRANULOCYTES
Neutrophils (PMNs)
Strongly phagocytic, important in controlling bacterial
infections
Usually first cells to arrive at site
Eosinophils
Weakly phagocytic, main role in allergic reactions, destruction
of parasites
Basophils
Non phagocytic
Cell surface receptors for IgE
Mediated allergic and antiparasitic responses due to release of
histamine
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DIFFERENCES BETWEEN NEUTROPHILS
AND MACROPHAGES
NEUTROPHILS
MACROPHAGES
Rapid increase in production
Only slight increase in blood
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(and in blood) during acute
phase of infection
Only found in inflamed tissues
Single mature form
Rapidly form pus
Short-lived; die after
phagocytosis
during inflammation
Found in healthy tissues
Multiple mature forms
Slowly form granulomas (with T
cell help)
Long-lived-survive after
phagocytosis
MONOCYTES/MACROPHAGES
Released from bone marrow
Circulate in blood and enter tissues where they mature into
macrophage
Activated macrophage
Initiated by phagocytosis of particulate antigens
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CELLS OF THE MONOCYTEMACROPHAGE SYSTEM
BLOOD - MONOCYTES
LYMPH NODES RESIDENT &
RECIRCULATING
MACROPHAGES
BRAIN - MICROGLIAL
LUNGS - ALVEOLAR
SPLEEN - MACROPHAGES
KIDNEY - MESANGIAL
LIVER - KUPFFER
CONNECTIVE TISSUE HISTOCYTES
BONE MARROW
- PRECURSORS
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JOINTS - SYNOVIAL A
MACROPHAGES: FUNCTION
Stand guard
Initiate early innate immune response
Educate the specific immune system
Present antigen associated with Class II MHC to CD4 TH cells
Call in the troops
Secrete cytokines that promote immune responses
Join the battle
Phagocytose and inactivate microbes
Secrete antibacterial substances, inflammatory mediators, and
complement components
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Phagocytosis
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NATURAL KILLER CELLS
Primary targets of NK cell killing are virus infected and
tumor cells
May depend on reduced expression of Class I MHC molecules,
alterations in surface carbohydrates
Mechanism of killing
Direct cytotoxicity
Antibody dependent cellular cytotoxicity (ADCC)
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Stages Of Inflammation
Blood vessels dilate in response to chemical mediators and
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cytokines
Edema swells tissues, helping prevent spread of infection
WBC’s, microbes, debris and fluid collect to form pus
Pyrogens may induce fever
Macrophages and neutrophils engage phagocytosis
Developmental Stages of Monocytes
and Macrophages
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INFLAMMATION
Tissue damage due to trauma, caustic agents, microbes
Mediated primarily by immune system cells, cytokines
Acute inflammation
Chronic inflammation
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Rubor, Calor, Tumor, Dolor
Rubor: Redness caused by increase circulation and
vasodilation in injured tissues
Calor: Warmth, heat given off by increased flow of blood
Tumor: Swelling, caused by increased fluid escaping into the
tissues
Dolor: Pain, causes by stimulation of nerve endings
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TRAUMA AND INFLAMMATION
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TRAUMA AND INFLAMMATION
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TRAUMA AND INFLAMMATION
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TRAUMA AND INFLAMMATION
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TRAUMA AND INFLAMMATION
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Activities Of Phagocytes
Stand guard
To survey tissue compartments and discover microbes,
particulate matter and dead or injured cells
Join the Battle
To infest and eliminate these materials
Educate Specific Immune System
To extract immunogenic information from foreign matter
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Chemical Mediators
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Complement
Consists of 26 blood proteins that work in concert to destroy
bacteria and viruses
Complement proteins are activated by cleavage
Classical pathway
Alternative pathway
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Complement
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Specific immunities
B and T lymphocytes
Specificity and memory
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Lymphocyte Development and
Differentiation
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Antigen
Presentation
Challenge of B
and T Cells
B Cell Antibody
Production
T Cell
Responses
Preliminary concepts
Cell receptors or markers confer specificity and identity
Major functions of receptors are
To perceive and attach to nonself or foreign molecules
To promote the recognition of self molecules
To receive and transmit chemical messages among other cells of
the system
To aid in cellular development.
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How Are Receptors Formed?
As a cell matures, certain genes that encode cell
receptors are transcribed and translated into protein
products with a distinctive shape, specificity and
function.
Receptor is modified and packaged by the endoplasmic
reticulum and Golgi complex.
It is ultimately inserted into the cell membrane,
accessible to antigens, other cells, and chemical
mediators.
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Receptor Formation in a Developing
Cell
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Major Histocompatibility Complex (MHC)
Receptors found on all cells except RBCs
Also known as human leukocyte antigen (HLA)
Plays a role in recognition of self by the immune system
and in rejection of foreign tissue
Genes for MHC are located on chromosome 6, clustered
in a multigene complex of classes I, II, III
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MHC Receptors
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Functions of MHC
Class I – markers that display unique characteristics of
self molecules and regulation of immune reactions
Required for T lymphocytes
Class II – receptors that recognize and react with foreign
antigens. Located primarily on macrophages and B cells
Involved in presenting antigen to T cells
Class III – secreted complement components, C2 and C4
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Clonal Selection Theory
Lymphocytes use 500 genes to produce a tremendous variety
of specific receptors
Undifferentiated lymphocytes undergo genetic mutations and
recombinations while they proliferate in the embryo forming
a billion different clones with the ability to react with a
tremendous variety of antigens.
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Ability to React to Every Antigen Is PreProgrammed
Lymphocyte specificity is preprogrammed, existing in
the genetic makeup before an antigen has ever entered
the system.
Each genetically different type of lymphocyte expresses a
single specificity.
First introduction of each type of antigen into the
immune system selects a genetically distinct lymphocyte
and causes it to expand into a clone of cells that can react
to that antigen.
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Structure of Antibodies
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Immunoglobulins
Immunoglobulin genes lie on 3 different chromosomes
Undifferentiated lymphocyte has 150 different genes for
the variable region of light chains and 250 for the
variable region and diversity region of the heavy chain
During development, recombination causes only the
selected V and D genes to be active in the mature cell.
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Gene Segments of Immunoglobulins
Heavy chains
Variable (V)
Diversity (D)
Joining (J)
Constant (C)
Light chains
Variable (V)
Joining (J)
Constant (C)
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HYPERSENSITIVITY REACTIONS
Type I (immediate) hypersensitivity: IgE-mediated
atopic (allergic) and anaphylactic reactions
Type II hypersensitivity: Ab-dependent cytotoxicity
Type III hypersensitivity: Immune complex induced
tissue damaging inflammation
Type IV (delayed) hypersensitivity:Cell-mediated
cytotoxicity
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TYPE II REACTIONS: Blood Typing and Transfusion
Reactions
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TYPE IV (DTH) REACTION: TB Skin Test
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IMMUNE REACTIONS DUE TO
MATERNAL ANTIBODIES
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Insect Stings
Normal reaction: local pain, erythema, swelling
Onset 10-15 minutes
Subsides in 1-2 hours
Therapy: cool compresses, analgesics
Insect Stings
Large, local reactions
Peak at 48 hours
Duration of 1 week
Occasional fatigue, nausea
Not IgE mediated
Therapy: antihistamines, prednisone
Insect Stings
Anaphylaxis: IgE mediated
Generalized urticaria, flushing, angioedema, cardiorespiratory
symptoms
Onset 15-20 minutes up to 72 hours
Adults have highest mortality
Prevention: avoidance, EpiPen, immunotherapy if skin test
positive
Fire Ant Stings
Fire Ant Stings
Ferocious; potent venom; multiple stings
Intense pain followed by pruritis
Immediate flare (2-5cm) and wheal (≤1cm)
8-10 hours later a sterile pustule develops
Systemic reactions (16%) rarely life threatening
Fire Ant Stings
Chance of being stung 50%
Reactions
Wheal & Flare 100%
Pustule 96%
Large local reaction 3.6-56%
Secondary infection 54%
Systemic 16%
Cutaneous
Life-threatening 0.6-2%
Deaths 32
http://afrsweb.usda.gov/fireant/venom.htm?pf=1
Allergic Reaction: Possible Causes
Insect bites/stings (bees, wasps, etc.)
Food (nuts, crustaceans, peanuts, etc.)
Plants
Medications
Others
Findings
Skin
Warm, tingling feeling
Face, mouth, chest, feet, and
hands
Itching
Hives
Respiratory System
Tightness in throat/chest
Cough
Swelling of the airway
Rapid breathing
Noisy breathing
Labored breathing
Inability to speak or cough
Retractions
Hoarseness
Use of accessory muscles
Stridor
Wheezing (audible without
stethoscope)
RESPIRATORY FAILURE!
RESPIRATORY ARREST!
Cardiovascular System
Increased heart rate
Decreased blood pressure
Decreased perfusion
(shock) due to
vasodilation
Generalized Findings
Itchy, watery eyes
Headache
Sense of impending doom
Runny nose
Other Signs and Symptoms
Decreasing mental status
Signs of shock (hypoperfusion)
Respiratory distress
Emergency Medical Care
Patient has prescribed epinephrine?
Facilitate administration of preloaded epinephrine.
Reassess every 2 minutes.
No auto-injector
CALL 911!!! Transport to ER