Care of Patients with Immune Disorders Adult Health Nursing June 16, 2009

Key Terms Antibody – a protein substance developed by the body in response to and interacting with a specific antigen. Antigen – substance that induces production of antibodies. B-cells – cells that are important for producing a humoral immune response. Cellular immune response – the immune system’s third line of defense, involving the attack of pathogens by T-cells. Cytokine – generic term for non-antibody proteins that act as intercellular mediators, as in the generation of immune response.

Genetics engineering – emerging technology designed to enable replacement of missing or defective genes. Helper T-cells – lymphocytes that attack foreign invaders (antigen) directly. Humoral immune response – the immune system’s second line of defense, often termed the antibody response. Immunity – the body’s specific protective response to an invading foreign agent or organism. Immunology – the study of the immune system.

Lymphokines – substances released by sensitized lymphocytes when they come in contact with specific antigens. Macrophages – any phagocytic cell involved in defense against infection. Memory cells – are responsible for recognizing antigens from previous exposure and mounting an immune response. Natural killer cells (NK cells) – lymphocytes that defend against microorganisms and malignant cells.

Phagocytic cells – they engulf, ingest, and destroy foreign bodies or toxins. Phagocytic immune response – the immune system’s first line of defense, involving white blood cells that have the ability to ingest foreign particles. Stem cells – precursors of all blood cells, that reside primarily in bone marrow.

Immunity is the quality of being insusceptible to or unaffected by a particular disease or condition.  It refers to body’s specific protective response to an invading foreign agent or organism.  The immune system functions as the body’s defense mechanism against invasion and allows a rapid response to foreign substances in a specific manner.

The body exhibits a wide array of adaptations to protect against antagonistic forces that are constantly attacking and threatening its integrity  The word immune is derived from the Latin word “immunis”, meaning “free from burden”.

Immunology is an evolving science that essentially deals with the body’s ability to distinguish self from non-self; and it is accomplished through a complex network of highly specialized cells and tissues that are collective called immune system.  Immune system also called the host defense system is critical to our survival.

Three main functions of the immune system: 1. to protect the body’s internal environment against invading organisms 2. to maintain homeostasis by removing damaged cells from the circulation 3. to serve as a surveillance network for recognizing and guarding against development and growth of abnormal cells.

Immunocompetence – a condition wherein the immune system responds appropriately to a foreign stimulus, and able to maintain the body’s integrity.  Immunocompetence is possible because the immune system is able or has the capacity to mobilize and use its antibodies and other responses to stimulation by an antigen. If the immune system response is to weak or too vigorous, homeostasis is disrupted, causing a malfunction or immunoincompetence.

Four categories of inappropriate responses of the immune system: Hyperactive responses against environmental antigens such as allergic reaction. Inability to protect the body as in immunodeficiency disorders such as in AIDS. Failure to recognize the body as self, as in autoimmune disorders such as in systemic lupus erythematosus, rheumatoid arthritis. Attacks on beneficial foreign tissue as in organ transplant or transfusion reaction.

TWO TYPES OF IMMUNITY a) Innate or Natural - The body’s first line of defense Provides physical and chemical barriers to invading pathogens and protects against the external environment. b) Adaptive or Acquired Immunity – second line of defense

The innate immune system is composed of: Skin and mucous membranes Cilia Stomach acid Tears Saliva Sebaceous glands Secretions and flora of the intestine and vagina Innate immunity does not always work, then adaptive immunity is the next line of defense.

TWO TYPES OF IMMUNITY, cont.. A) INNATE OR NATURAL - The body’s first line of defense B) ADAPTIVE, OR ACQUIRED, IMMUNITY - This is the body’s second line of defense against disease. It provides a specific reaction to each invading antigen and has the unique ability to remember the antigen that cause the attack. It is composed of highly specialized cells and tissues, including the thymus, spleen, bone marrow, blood and lymph.

ADAPTIVE, OR ACQUIRED, IMMUNITY - Adaptive, or acquired, immunity includes both humoral and cell-mediated immunity. The characteristics of an adaptive immune system are specificity (i.e., being specific) and memory. This special immunity results from the production of antibodies in the cells. Antibodies develop naturally after infection or artificially after vaccinations.

Adaptive or Acquired Immunity If the components of innate or natural immunity fail to prevent invasion or destroy a foreign pathogens the adaptive or acquired immunity is summoned to assist the fight. Adaptive or acquired immunity provides a specific reaction to each invading antigen and has the unique ability to remember (memory) the antigen that caused the attack.

The major components/structure of the immune system include the: Bone marrow White Blood cells produced by bone marrow Lymphoid tissues including:  the thymus gland,  the spleen,  the lymph nodes,  the tonsils, and adenoids, and similar tissues in the GI tract, respiratory, and reproductive system

Adaptive immunity protects the internal environment. It is acquired during life but not present at birth, usually develops as a result of prior exposure to an antigen through immunization (vaccination) or by contracting a disease, both generate a protective immune response. Adaptive immunity utilizes cells in defending the body. It includes both humoral (B-cells) and cell- mediated immunity (T-cells). A specific type of white blood cell, known as lymphocyte, is involved in the defense.

* Acquired or Adaptive immunity is further classified into two: 1. Active 2. Passive

* Active Acquired Immunity– the immunologic defenses are developed by the person’s own body. It typically lasts many years or even lifetime. Individual develops antibodies in response to having a disease process or by response to artificial antigens such as a vaccine or toxoids. Response can be boosted and maintained via repeated injections.

Passive Acquired Immunity – is temporary immunity transmitted from a source outside the body that has developed immunity through previous disease or immunization. Example: immune globulin or antiserum obtained from the blood plasma of people with acquired immunity is used in emergencies to provide immunity to diseases when the risk for contracting a specific disease is great (after exposure to hepatitis) that there is no enough time for a person to develop adequate active immunity.

Another example of passive acquired immunity is the transfer of antibodies from the mother to an infant in utero or through breast feeding. Passive acquired immunity requires an antibody be introduced to individual, either by maternal transfer (placenta and/or colostrum) or immune serum antibody injection, to promote a specific antigen response. Another example is tetanus immune globulin.

Macrophages (phagocytic immune response) When organisms pass the epithelial barriers, phagocytes (macrophages) become activated. They have the ability to migrate through blood stream to the tissues for the body’s second line of defense against disease. Phagocytes engulf and destroy microorganisms that pass the skin and mucous membrane barriers. These cells also assist in the immune response by carrying antigens to the lymphocytes.

Lymphocytes Lymphocytes include the T and B cells, and the large, granular lymphocytes also known as natural killer, or NK cells. T-cells (processed in the thymus) Approximately 70% - 80% of lymphocytes are T-cell lymphocyte. When activated T- cell release a chemical substance called Lymphokine it attracts macrophages to the site of infection or inflammation and prepares them for attack.

T-cells cooperate with the B-cells to produce antibodies but do not produce antibodies themselves. T-cells are responsible for cell-mediated immunity and provide the body with protection against viruses, fungi, and parasites. T-cells also provide protection in allograft and against malignant cells.

Cellular Immunity Cellular immunity is also called cell- mediated immunity, results when T-cells are activated by an antigen. Once these T cells have been sensitized, they are released into the blood and body tissues, where they remain indefinitely. On contact with the antigen to which they are sensitized they will attach to the organism and destroy it.

Cellular Immunity is important in: Immunity against pathogens that survive inside cells including viruses and some bacteria (mycobacterium) Fungal infections Rejection of transplanted tissues Contact hypersensitivity reactions Tumor immunity Certain immune diseases

B-cells (processed in the red marrow) B-cells make up approximately 20% - 30% of the lymphocytes. B-cells cause the production of antibodies and proliferate in response to a particular antigen. B-cells migrate → peripheral circulation and tissues filtered from the lymph and stored in the lymphoid tissue of the body.

B-cells (processed in the red marrow) B cells are responsible for humoral immunity, produce antibodies and provide protection against bacteria, viruses, and soluble antigens. T and B cells they both originate in red bone marrow.

B Cells -The cells of the immune system that make antibodies to invading pathogens like viruses. They form memory cells that remember the same pathogen for faster antibody production in future infections.

Humoral Immune Response Humoral immunity responds to antigen such as bacteria and foreign tissue. It is the result of the development and continuing presence of circulating antibodies in the plasma. It is sometimes called the antibody response. Humoral immunity begins with the B- lymphocytes, which transforms themselves into plasma cells that manufacture antibodies in response to antigen challenge. The concept of memory is important to success of humoral immunity.

Differences in Cellular and Humural Immune responses Cellular Responses (T-Cells)Humoral Responses (B-Cells) Transplant rejectionBacterialphagocytosis&lysis Delayed hypersensitivity (TB – PPD) Anaphylaxis Graft-versus-host diseaseAllergic hay fever &asthma Tumor surveillance or destructionImmune complex disease Intracellular infectionBacterial and some viral infections Viral, fungal, and parasitic infections

Antigen or allergen Antigen or allergen is the invading or attacking organism that is responsible for stimulating antibody production.

Example of allergen or antigen: A single bacterium or large molecule, such as diphtheria or tetanus toxin may have several antigens, or markers, on its surface, thus inducing the body to produce a number of different antibodies. Once produced, an antibody is released into the bloodstream and carried to the attacking organisms. There it combines with the antigen, binding it like an interlocking piece of jigsaw puzzle.

There are four (R’s) well defined stages in an immune response: Recognition – recognized self from non-self Respond – produce antibodies Remember – ability to remember Regulate – self-regulation, ability to turn off thus preventing chronic inflammatory response

Immunocompetence is the ability of an immune system to mobilize and deploy its antibodies and other responses to stimulation by antigen. Both the number and functions of the helper and suppressor T cells help determine the strength and persistence of an immune response. The normal ratio of helper T cells to suppressor T cells in the body is 2 : 1, when this ratio is disrupted, autoimmune and immunodificient disease occur.

COMPLEMENT SYSTEM The complement system is a system of approximately 25 serum enzymatic proteins that interact with one another and with other components of the innate (natural) and adaptive (acquired) immune systems.  Normally, complement enzymes are inactive in plasma and body fluids.

COMPLEMENT SYSTEM When an antigen and antibody interact, the complement system is activated. Complement functions in a “step-by- step” series much like the clotting mechanism, but with different purpose. The complement system can destroy the cell membrane of many bacterial species, and this action attracts phagocytes to the area.

Genetic Control of Immunity More is being discovered about the genetic role in immunity. There is a genetic link to both well-developed immune system and poorly developed or compromised immune systems. The immune system develops at different rates and at different times in fetal and early life. For humans, bone marrows provides the continuous service of stem cells and all the other cells involved in the immune response.

EFFECTS OF NORMAL AGING ON THE IMMUNE SYSTEM With advancing age, there is a decline in the immune system.  The primary clinical evidence for this immunosenescence is the high incidence of tumors in older adults.  A greater susceptibility also occurs to infections (such as influenza and pneumonia) from pathogens that an older person has been relatively immunocompetent against earlier in life.

EFFECTS OF NORMAL AGING ON THE IMMUNE SYSTEM Aging does not affect all aspects of the immune system. The bone marrow is relatively unaffected by increasing age. However, aging has a pronounced effect on the thymus, which decreases in size and activity with aging. These changes in the thymus are probably a primary cause of immunosenescence.

EFFECTS OF NORMAL AGING ON THE IMMUNE SYSTEM However, the most significant alterations seem to involve T cells. As thymic output of T cell diminishes, the differentiation of T cells in peripheral lymphoid structures increases. Consequently, there is an accumulation of memory cells rather than new precursor cells responsive to previously unencountered antigens.

EFFECTS OF NORMAL AGING ON THE IMMUNE SYSTEM Delayed hypersensitivity response is frequently decreased or absent in older adults. The clinical consequences of a decline in cell-mediated immunity are evident. Diminished responses to delayed hypersensitivity skin tests in older adults are related to an increased risk of cancer mortality, as well as mortality in general (Older Adult Considerations box).

To be continued..