The Immune System Lecture

8/8/2019 The Immune System Lecture

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By: Catherine M. Souribio, R.N.



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.



` 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.



` 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.



` 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)



` 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.



` 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.



` 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.



` 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.



` 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.)



` 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.



` 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.



` 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.



` 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.



` 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.



` 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)



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.



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.



` 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.



` 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.



` * 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.



` 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.



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.



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.





` 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.



` 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.



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.



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



Slide 29

A1 Alex, 10/5/2010



̀Are foreign substances

which elicit an immune

response and are also

capable of combining with

products of the immunesystem.



` Antigen Antibody Reactions

1. Agglutination - clumping together

2. Precipitation - antibodies react

with soluble antigensresulting in an

insoluble complex

which then precipitate



` 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.



` 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.



` 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.



` 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.



` 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.



* 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.



` 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.



` 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.



` 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.

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The Immune System Lecture

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