The Immune System and the Immunocompromised Patient - PowerPoint Presentation

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The Immune System and the Immunocompromised Patient

Chapter 4

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Introduction

Molecules recognized as “non-self” are antigens

Several mechanisms to protect itself

First level of protection include physical and biochemical-skin, acid in stomach

Second level of protection phagocytic cells, enzymes, and proteins

Final level of protection is the adaptive immune system

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Physical Barriers to Infection

Skin-lactic acid and sebaceous glands create a low pH to prevent growth of microorganisms

Sometimes microbes that are normal flora on the skin tend to invade the body when there invasive procedures done

Damaged skin can provide a portal of entry

Tetanus spores in contaminated soil

HIV and Hepatitis B by contact with contaminated blood or body fluids

Incisional wounds

Insect bites

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Physical Barriers to Infection

Respiratory Tract-hairs in our noses filter particles; cough reflex prevents aspiration; membrane that lines tract secretes mucus

Cilia-small hairs like projections move mucus constantly, propelling out the mucus towards the mouth

Lysozyme-an enzyme in tears, nasal secretions and saliva helps to breakdown bacterial cell walls especially Gram positive bacteria

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Physical Barriers to Infection

Gastrointestinal tract-juices in stomach highly acidic, pH between 2 and 3 to help destroy ingested bacteria

Bile in small intestine keeps bacterial growth from happening

Large intestine contains bacteria the discourages growth of pathogens and compete for nutrients

Remember antimicrobial therapy may destroy some of the normal flora and allow possibly pathogenic bacteria to grow such as Clostridium difficile.

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Physical Barriers to Infection

Genitourinary tract-protected by mucous lining preventing microorganisms from adhering and growing. Constant flow of urine helps to flush out bacteria.

In vaginal canal production of lactic acid enabling a low pH between 4 and 5 from allowing other species from growing

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The Innate Immune Response

Phagocytic Cells

2 types-Neutrophils and Macrophage-engulf foreign particles by process of phagocytosis.

Neutrophils and macrophages both formed in bone marrow

Neutrophils live about 6-8 hours-granules inside contain enzymes such as lysozymes and lactoferrin

Macrophages-released as monocytes in blood then become macrophages; live longer in tissues. In spleen and then the spleen filters out foreign material; pass into tissues ingesting microorganisms; then display on surface of cell and to be recognized by T and B lymphocytes

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The Innate Immune Response

Interferons

Cytokines is a family of chemical messenger molecules

Synthesized and excreted by cells infected with a virus

Work on the uninfected cells and inhibit the viral RNA from synthesis by using enzymes; preventing the spread of viruses through tissues

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The Innate Immune Response

Lactoferrin circulates in the blood forming complexes of iron to prevent it from being available for microbes to grow

Acute Phase Proteins-proteins that appear in plasma in response to infection

Complement proteins-a series of proteins, have several important effects essential for phagocytosis to happen

Mast Cells-found in tissues and similar cells, basophils in the blood-release mediators known as histamine, leukotrienes, and prostaglandin to get in and out of blood vessels and attract the phagocytic cells

Acute Inflammatory Response-increase of capillary dilation to allow more fluid to the area causing the erythema and edema and works with phagocytes to be able to be able to repel microorganisms

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The Adaptive Immune Response

Some microbes can evade the innate immune defenses.

Lymphocytes help by interacting with specific antigens by being able to remember previous encounters with an antigen providing a rapid response the next time.

Box 4.1 Fever

2 types of lymphocytes B and T. B lymphocytes produce antibodies referred to as the humoral immune system; T lymphocytes destroy abnormal or tumor cells infected with viruses. They are referred to as the cell mediated immune system. Also produce cytokines that activate other lymphocytes and macrophages.

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The Adaptive Immune Response

Antibodies are Y shaped proteins called globulins or

immunoglobulins.

Five types of immunoglobulins

IgG-most abundant, coats bacteria to help with phagocytosis and neutralize bacterial toxins; crosses the placental in last 3 months

IgM-First to appear in an attach against antigen; stays in the blood

IgA-Works on microbial invasion of mucous membranes-reproductive, respiratory, gastrointestinal and urinary

IgE

-Attached to mast cells-associated with allergic response; and thought to be involved in destruction of parasites

IgD

-Maximum found in childhood function is unknown, play in role of activation of other Ig

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The Adaptive Immune Response

T lymphocytes formed in bone marrow, but mature in the thymus gland

Recognition of Infected Cells-T cells need to be able to identify infected cells; recognized the non-self antigens on the surface of infected cell

Destruction of Intracellular Pathogens-carried out by the T cells.

Memory Cells-Both B and T lymphocytes produce memory cells

Monoclonal Antibodies-used in research and can provide very specific and sensitive tests enabling particular proteins to be isolated from complex mixtures.

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The Adaptive Immune Response

Organs of the immune system

-lymphoid tissue if found throughout the body

Connected by a network of small channels called the lymphatic system

Lymphoid tissue is in the liver, spleen, gut (Peyer’s patches and appendix) tonsils, and adenoids

Lymph nodes throughout the body where lymph and blood vessels come together

Made in the bone marrow several kinds

Will migrate after matured to lymphoid tissue

Response to Invasion

-microbe goes to lymph node or lymphoid tissue. T lymphocytes bind to antigens and trigger immune

response..infected

area will have swelling and pain

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Immunity to Infection

B and T lymphocytes help to develop a more rapid response to antigens, this is natural acquired immunity

Passive immunity is when a person receives an injected antibody like IgG for a specific microbe

Immunization-pioneered by Edward Jenner in 1796 when he was able to demonstrate that could be protected from smallpox

Vaccines-is to induce a specific immune response against a particular micro-organism without causing the actual disease

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Immunity to Infection

Vaccines-

Table 4.4 Types of Vaccines and Use

Killed micro-organisms-

made from whole cells that have been killed or from purified components of the cell-several doses required

Live-attenuated-

use live micro-organisms that have been treated, altering their structure to prevent them causing infection. Resulting in high level of antigen production.

Inactivated toxin-

toxins produced by a micro-organism are inactivated by treatment with formaldehyde. Although the resulting toxoid induces an immune response, its toxic activity is destroyed.

Genetically engineered-

Gene manipulation techniques have now been applied to vaccine production.

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Immunity to Infection

Administration of Vaccines

Passive Immunization

Damaged Immune System

Young children-immature immune system

Elderly-diminished immune response

Physical or emotional stress

Poor nutrition

Disease Associated with Immune Deficiency

Genetic disorders, autoimmune diseases, chemotherapy, certain viral infections such as HIV

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BIRTH TO 15 MONTHS

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ADULT IMMUNIZATION SCHEDULE AS OF 2019

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Preventing Infection in the Immunocompromised Patient

Immunocompromised Host

Type of infection depends which part of the immune system is affected

Cellular or T cell response will allow intracellular infections will be predominate-remember attacks cells that have been invaded

Humoral or B cell response will allow bacterial infections to increase

Phagocytic cells being reduced will allow infections especially Gram negative bacteria

Granulocytopenic

patients will be more vulnerable to infections from opportunistic pathogens; more susceptible to inhaled or ingested microbes

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Preventing Infection in the Immunocompromised Patient

Immunocompromised Host

-Protective Isolation or Reverse Isolation

Accommodation-need to be in room that is not exposed to people with infections such as chickenpox, respiratory tract infection

Severely neutropenic patients are at risk for infections from aspergillosis should be in room with positive pressure ventilation; HEPA filter

Need to consider psychological effects-feeling alienated

Need to teach visitors to about handwashing or alcohol rub

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Preventing Infection in the Immunocompromised Patient

Immunocompromised Host-Protective Isolation or Reverse Isolation-also known as

Neutropenic Precautions

Handwashing

Personal Protective Equipment

Equipment

Cleaning

Flowers and pot plants avoided severely immunocompromised patients

Food

Avoid raw fruit and vegetables

Vegetables cooked should be washed and peeled

Meat cook thoroughly

Food storage appropriate

Reheating of foods; home cooked meals could present a problem

Avoid raw or undercooked foods, soft cheeses, precut sandwiches and salads may contain listeria

Invasive procedures

Care of Intravenous and urinary catheters