the immune system lecture
TRANSCRIPT
8/8/2019 The Immune System Lecture
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By: Catherine M. Souribio, R.N.
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Is an intricate network of specialized cells, tissues, andorgans designed to allow us to exist in an environmentthat often includes hostile microorganisms. The systemhas evolved to protect and defend the body againstinvasion by bacteria, viruses, fungi, and parasites. It also
seeks out and destroys malignantly transformed cells.The significance of a healthy immune system is apparentin states or diseases characterized byimmunodeficiency, such as occur s in HIV infection or inpatients on immunosuppressive medication. Without aneffective immune system, an individual is at risk for thedevelopment of overwhelming infection, malignantdisease, or both. On the other hand, excessive or inappropriate activity of the immune system can result inautoimmune disease, hyper sensitivity states, or immunecomplex disease.
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` This chapter aims to assist you, nur sing students
to develop the essential knowledge, skills and
attitudes to provide quality, compassionate and
humane care among clients with immunologicdisorder s.
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` The pur pose of the Immune System is to rapidly
encounter and respond to any foreign invader, it is
not sur prising that the cells, tissues, and organs
comprising the lymphoid system are widelydistributed throughout the body. Furthermore, the
mobility of immune cells allows them to circulate
and move in and out of tissues so that they can
survey the body for pathogens, cellular debris,virus-infected cells, and tumor cells.
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` Immune System are located throughoutthe body.
` Organs include: thymus, bone marrow,
lymph nodes, spleen, tonsils, appendix,Peyer¶s patches of small intestine.
` Main cell types are WBC¶s (especially
lymphocytes, plasma cells, andmacrophages)
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` All originate from the same stem cell in bone
marrow, then differentiate into separate types:
(Cells of the Immune System)
` Granulocytesa. Eosinophils: increase with allergies and
parasites.Protect humans against
helminth(parasitic worm such as intestinal
pinworms, and tapeworms.)` b. Basophils: contain histamine and
increase with allergy and anaphylaxis.
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` c. Neutrophils: involved in phagocytosis.- neutrophils leave the vascular
compartment and enter tissue spaces searching outbacteria or cell debris, which they can phagocytize
and destroy.- In the process of phagocytosis, whichliterally means cell eating, the bacteria or debris areengulfed and taken up into the phagocytic cells.
- neutrophils cannot replicate and diefollowing phagocytosis. The accumulation of deadneutrophils contributes to the formation of pus.
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` Neutrophilia ± An increase in circulating
neutrophils or characterized by an excess number
of immature neutrophils.
` Neutropenia - A decreased number of circulating
neutrophils, is primarily seen in hematologic
malignancies, cytotoxic therapy, or aplastic
anemia.
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` Monocytes ( macrophages- literallymeans big eater s) eg..histiocytes( inthe loose connective tissue), Kupffer
cells( in the liver ): Involved inphagocytosis.
` Lymphocytes (T cells and B cells):Involved in cellular and humoralimmunity.
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` WBC ± has 4000 to 10,000 cells per cubic millimeter
of blood.
*Leukocytosis ± an increase in the circulating
number of WBCs.( occur s those leukocytes that have
marginated along the vascular endothelial surface or
entered tissue spaces or lymphatics.)
* Leukopenia ± a decrease in the total number of
circulating WBCs.(occur s in bone marrow
suppression, or increased peripheral destruction of WBC which might occur with splenomegaly.)
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` Granulocytes: (because of the granular appearance of their cytoplasm.)
1. Neutrophils ± 40 to 75 % of bloodleukocytes.
2. Eosinophils ± 2 to 5 % of leukocytes.
3. Basophils - 0.2 to 0.5 % of leukocytes.
4. Monocytes - 2 to 6 % of the total WBCcount.
5. Lymphocytes ± 20 to 35 % of the total WBCcount.
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` Originate from stem cells in the bone marrow and
differentiate or mature into either B or T cells.
` T cells - differentiates in the thymus gland, where
it learns to discriminate self -antigen from nonself -antigen.
- Interact directly with cellular targets and
are responsible for cell-mediated immunity.
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` B Cells - is thought to mature and becomeimmunocompetent in the bone marrow.
- When stimulated by an antigen, B cells further differentiate into plasma cells, whichsecrete soluble molecules called antibodies intothe body¶s fluids.
- Antibodies mediate humoral immunity.
* Both T and B lymphocytes continually recirculate
between blood, lymph, and lymph nodes.
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` Primary Lymphoid organs:
- Bone marrow
- Thymus
Bone marrow - is the soft tissue inside the hollowof long bones and is a major site for proliferation
and maturation of immune cells from
undifferentiated stem cells.
Thymus - is a multilobed gland located in themediastinum anterior to and above the heart.
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` The thymus is large in the newborn and child and
gradually involutes with age.
` Occasionally, transient involution may occur
during childhood because of severe infection,stress, trauma, or burns.
` Within the thymus T lymphocytes multiply and
become capable of an immune response.
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` Lymph nodes - are disper sed along lymphaticvessels and form cluster in the neck, axillae,abdomen, and groin.
- enlarged nodes are useful diagnostic signof infection or malignant disease.
` Spleen ± is located in the upper abdomen andcontains two types of tissue: the red pulp and whitepulp.
*Red pulp ± contains phagocytic cells thatdispose of damaged or aged red blood cells.
* White pulp ± contains lymphoid tissue.` Tonsils ± palatine tonsils in the oropharynx` Adenoids (pharyngeal tonsil)
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1. Cellular Immunity
a. Mediated by T cells: Per sist intissues for months or years.
b.Functions: transplant rejection,delayed hyper sensitivity, tuberculinreactions, tumor
surveillance/destruction, intracellular infections.
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2. Humoral Immunity
- Mediated by B cells:
a. Production of circulating
antibodies (gamma globulin)
b. Only survive for days.
- Functions: bacterial phagocytosis,
bacterial lysis, virus and toxinneutralization, anaphylaxis, allergic hay
fever and asthma.
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` 1. Self-or Non-Self Recognition ±normally recognizes host cells as non-antigenic and responds only to foreign
and potentially harmful agents, living or non-living as antigens.
` 2. Antibody Production ± produces specific antibodies for specific antigens for destruction.
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` 3. Memory ± remember s antigens
that have invaded the body in the
past, allowing a quicker response.` 4. Self ± Regulation± monitor s its
own performance, turning itself on
when antigens invade and turningitself off when infection is eradicated.
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` * In Autoimmune Response, there is
a breakdown in this distinction.
Because of the damage in theimmune system due to pathologic
changes, an autoimmune response
may occur in response to certain
body¶s own protein resulting in the
production of autoantibodies.
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` 1. Defense - Involves resisting infection
-Protection against
antigens.` 2. Homeostasis - removal of worn out or
damaged components (eg..dead cells)
` 3. Surveillance- deals with theidentification and destruction of mutant cells or the
nonself cells.
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1. IgG ( 75% of the total immunoglobulins)
* The most abundant antibodies.
* Can cross the placenta, responsible for
immunity in the newborn.* Neutralizes toxins and viruses.
2. Ig A ( 15% of the immunoglobulin pool)
* Located in the saliva, tear s, colostrum and
mucus of the respiratory, digestive urinary
tracts, breast milk and reproductive tracts.
* Adds protection against enteric viruses in
the breastfed infant.
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3. IgM ( 10% of the total plasma immunoglobulin)* The largest of the immunoglobulins in
molecular size.* Second most abundant antibodies.
* Fir st to appear in fetal life.* Fir st to form during viral or bacterial
infection.4. IgE ( < 1.0% has trace amounts within the
blood)* Responsible for some allergic responses,trigger s release of histamine.
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` They neutralize the invader or make it more vulnerableto attack from macrophages and neutrophils.
` They can opsonize antigen and precipitate solubleantigen, all of which make it more susceptible to
phagocytosis by macrophages.` Antibodies can directly bind to bacterial toxins and
neutralize them.
` Antibodies can also coat foreign cells or tumor cells and make them vulnerable to attack by leukocytes.This is called antibody dependent cell mediatedcytotoxicity.
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` There are two major types of immunity:
1. Natural (or Innate) Immunity
2. Acquired (or Adaptive) Immunity
A. Natural (Innate) Immunity- Immune responses that exist without
prior exposure to an immunologically active
substance.
_ Genetically acquired immunity is natural immunity.
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B. Acquired (or Adaptive) Immunity
1. Immune responses that develop during thecour se of a per son¶s lifetime.
2. Acquired Immunity may be further classifiedas naturally or artificially acquired, active or passive..
Active Immunity ± results when the bodyproduces its own antibodies in response to an
antigen. Passive Immunity ± results when an antibody is
transferred artificially.
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a. Naturally acquired active immunity: - results from having the disease and recovering
successfully.b. Naturally acquired passive immunity:
- antibodies obtained through placenta or breastmilk.c. Artificially acquired active immunity:
- conferred by immunization with an antigen.d. Artificially acquired passive immunity:
- antibodies transferred from sensitized per son(eg..,immune serumglobulin/ gamma globulin)
A1
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Slide 29
A1 Alex, 10/5/2010
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̀Are foreign substances
which elicit an immune
response and are also
capable of combining with
products of the immunesystem.
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` Antigen Antibody Reactions
1. Agglutination - clumping together
2. Precipitation - antibodies react
with soluble antigensresulting in an
insoluble complex
which then precipitate
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` Antigen - Antibody Reactions
3. Neutralization - antibodies combine with
all toxin.
4. Lysis - antibodies attack all
membrane and cause cell
rupture.
5. Opsonization - antibodies coat bacteria
and increase their susceptibility to phago-
cytosis.
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` After exposure to an antigen, there is a delay or latent
period in which little or no antibody can be measured
in the serum. It is during this latent period that the B
cell recognizes antigen and differentiates into a
plasma cell.
` By 4 to 10 days after the initial exposure, serum
antibody levels rise with IgM appearing fir st and then
IgG. This is the Primary Immune Response, and
usually, the peak levels of antibody rapidly decrease;however, memory cells are produced, which are able
to recall this antigen.
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` Memory cells recirculate for several year s
through body tissues and lymphoid organs,
seeking reexposure to the specific antigen they
are programmed to target.` On reexposure to the same antigen, the
antibody is produced within 1 to 2 days, and the
level is often 50 times greater than that of the
primary response. The levels also remainelevated for a longer period of time and fall off
slowly over the cour se of months.
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` Thus, the secondary immune response
occur s faster, is more intense, and has a
longer duration of peak antibody titer, all
due to the presence of memory cells. Withsubsequent exposure, the antibody
response can be boosted to even higher
levels.
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` Genetics
* various immunodeficiency diseases can becongenitally acquired as a consequence of anembryologic insult or an enzyme defect, such as
adenosine deaminase deficiency.( AD A)` Age
* The very young and the elderly are moresusceptible to infection.
*Components of both the innate, humoral, andcell-mediated immune responses are underdevelopedin the newborn.
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* Immunization of an infant typically does notbegin until approximately 3 months of agebecause prior to this time, the infant is incapableof producing antibody and memory cells in
response to the antigen in the vaccination.* In the elderly the thymus has atrophied and
there is a decrease in thymic hormones.
* The decline in immune function with age may
be related to the presence of chronic illness in theelderly.
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` Nutrition
* Adequate nutrition is vital to promoteoptimum immune function.
* Protein deficiency impair s humoral and cellmediated immune responses because proteins are required for the proliferation of leukocytes, thesynthesis of immunoglobulins and the proteins of the complement cascade.
* Trace elements, such as copper and zinc,and vitamins are important, in maintaining ahealthy immune system.
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` Medications
* A large number of medications can depress
the immune system.
* Some medications may be taken specificallyfor their anti-inflammatory or immunosuppressive
properties, whereas other s taken for unrelated
indications have side effects that suppress
immunity.
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` Stress
* Acute physical stressor s, such as trauma andburns are accompanied by depressed immune cellfunction, and if the affected individual survives the
initial insult, he or she will be at risk for infection.*Stress, both emotional and physical, trigger s
activation of the autonomic nervous system andthe endocrine system. Both of these systems can
in turn affect the immune response.