Lymphoid System and Defenses Against Diseases PDF

Lymphoid System and Defenses Against Diseases Marie A. Román Martínez, PhD Department of Biology Office hours: by appointment Email: [email protected] Copyright-This presentation is intended for educational purpose only. No part of this presentation may be reproduced or transmitted in any form wit...

Lymphoid System and Defenses Against Diseases Marie A. Román Martínez, PhD Department of Biology Office hours: by appointment Email: [email protected] Copyright-This presentation is intended for educational purpose only. No part of this presentation may be reproduced or transmitted in any form without written permission. Primary Immune Response Occurs with the first encounter of a pathogen or non-self antigen. Stimulates T and B cells Become activated and proliferate and make clones to destroy the antigen. Produces memory cells that recognize the same antigen if it reenters the body. Secondary Immune Response Occurs with another invasion of the same antigen. Memory T and B cells launch a more rapid and intense response than the primary immune response. Types of Immunity There is more than one way for a person to develop immunity to a particular pathogen. Mechanisms are grouped into two broad categories: 1. Active immunity Acquired through the use of a person’s immune response. Leads to the development of memory cells. 2. Passive immunity Acquired without the activation of a person’s immune response. No memory is developed. Types of Immunity 1. Active immunity (cont.) Naturally acquired active immunity ‒ Results after a person is exposed to a pathogen. ‒ Person gets sick and recovers. ‒ Leaves antibodies and memory T and B cells to fight later infections via a secondary immune response if it reenters the body. Artificially acquired active immunity ‒ Person receives a vaccine of dead, weakened, or inactivated pathogens or their antigenic parts. ‒ Triggers a primary immune response that forms memory T and B cells and antibodies to fight the pathogen if it reenters the body. ‒ Booster shots cause a secondary response to boost antibody levels. This Photo by Unknown Author is licensed under CC BY-NC-ND Types of Immunity 2. Passive immunity (cont.) Naturally acquired passive immunity ‒ Infants receive maternal antibodies IgG through placenta and IgA in breast milk. Artificially acquired passive immunity ‒ Receiving injections of antibodies produced by another person, animal, or synthetically. ‒ Called antiserum. ‒ Used in emergency situations when the pathogen acts too severely and quickly. Rejection of Organ Transplants Organ transplants are viable treatment options for persons with a terminal disease of certain organs such as the heart, kidneys, and liver. Major challenge after transplant is organ rejection. The lymphoid system recognizes the new organ as non-self and attacks it. To limit chance of rejection University of Maryland School of Medicine Faculty Scientists and Clinicians Publish Findings of World’s First Successful Transplant of Genetically Modified Pig Heart into Human Patient https://www.medschool.umaryland.edu/news/2022/university-of-maryland-school-of-medicinefaculty-scientists-and-clinicians-publish-findings-of-worlds-first-successful-transplant-ofgenetically-modified-pig-heart-into-human-patient.html Determine compatibility of donor and recipient tissues. Compare human leukocyte antigens (HLAs) group A. The closer to 100% the better the chance of avoiding rejection. Rejection of Organ Transplants To limit chance of rejection Immunosuppressive therapy is administered: The lymphoid system must be suppressed sufficiently to prevent rejection of the organ but not enough to eliminate immunity against pathogens. Cyclosporine– is a selective immunosuppressive drug that inhibits T cell activity with minimal B cell effects. T cells are primarily responsible for organ rejection. B cells are still able to provide antibody-mediated immunity against pathogens. Bacterial and viral infections are primary causes of death among transplant recipients. Immunosuppression also increases cancer risk. Disorders can be grouped as: Infectious disorders Noninfectious disorders Infectious Disorders: Acquired immunodeficiency syndrome (AIDS) Caused by the human immunodeficiency virus (HIV) Attacks and kills TH cells. Invades macrophages, which serve as a reservoir for the virus. Immune defenses in the individual decrease. Leads to development of secondary diseases that ultimately lead to death: Kaposi sarcoma-cancer No cure but there are drugs that slow disease progression. Transmission occurs by: (does not occur through tears or saliva) Sexual intercourse→ vaginal fluids and semen. Exchanges of blood→ needles, exposed wounds, mucous membranes. Childbirth→ infected mothers may transmit HIV to infants during childbirth. Kaposi Sarcoma https://www.nature.c om/articles/d41586023-00479-2 Infectious Disorders: Elephantiasis Tropical disease spread by bites of certain mosquito species. Characterized by greatly swollen (edematous) lower limbs or other body parts. Lymphatic vessels are blocked by round worms. Fluid accumulates in tissues drained by the plugged lymphatic vessels. Lymphadenitis Inflammation of the lymph nodes. “swollen glands” Common complication of bacterial infections. Bubo → a severe swollen lymph node. Noninfectious Disorders Allergy or hypersensitivity: Abnormally intense immune response to an antigen harmless to most people. Such antigens are called allergens. Sometimes allergies are triggered by a combination of environmental factors rather than by an identifiable allergen. Such cases are difficult to treat because most drugs don’t work against these types of reactions. Sensitization to an allergen results in reactions whenever exposure occurs. Reactions can be immediate or delayed. Noninfectious Disorders Allergy or hypersensitivity: Occur when allergens bind with IgE antibodies on mast cell surfaces. Cells release histamine, which stimulates an inflammatory response. Localized reactions are unpleasant but not life threatening. E.g., hay fever, hives, allergy-based asthma, and digestive disorders. Systemic reactions (anaphylaxis) are life threatening. Impair breathing and cause circulatory failure due to a sudden drop in pressure as blood vessels dilate and fluid moves into the tissues. E.g., bee stings and penicillin. Delayed reactions Appear 1 to 3 days after antigen exposure. Due to cytokines from T cells. E.g., poison ivy Noninfectious Disorders Autoimmune diseases: T and B cells recognize body tissues as non-self. Produces an immune response. Due possibly to change in body molecules are no longer recognizable as self. E.g., rheumatoid arthritis, which destroys joints and type I diabetes, which destroys beta cells in the pancreas. Lymphoma: Any tumor of lymphoid tissue. Hodgkin lymphoma: Malignant lymphoma, which is cancer of lymphoid tissue involving the production of B cells. Enlarged and painless lymph nodes (lymphadenitis), fatigue, fever, night sweats. Early treatment with chemotherapy and radiation yields a high cure rate. Noninfectious Disorders Severe combined immunodeficiency (SCID): Group of disorders resulting from several different genetic defects: Marked deficit or absence of both T and B cells. Lymphoid system is basically nonfunctional. Infants have little or no protection against pathogens and usually die within one year. Stem cell transplants from the red bone marrow David was born in 1971 with severe combined or umbilical cord blood and gene therapy have immunodeficiency (SCID) and was forced to live been successful in some cases. in a specially constructed sterile plastic bubble from birth until he died at age 12. https://youtu.be/yLqhEZKxsoo Objectives 1. Describe the formation of lymph. 2. Describe the pathway of lymph in its return to the blood. 3. Describe how lymph is propelled through lymphatic vessels. 4. Describe the locations and functions of the red bone marrow, thymus, lymph nodes, and spleen. 5. Describe the locations and functions of the tonsils and mucosa associated lymphoid tissues. 6. Identify the components of nonspecific resistance. 7. Compare nonspecific resistance and specific resistance. 8. Explain the mechanism of cell-mediated immunity. 9. Explain the mechanism of antibody-mediated immunity. 10. Compare primary and secondary immune responses. 11. Explain the basis of vaccination. 12. Explain how rejection of a transplanted organ occurs. 13. Describe the common disorders of the lymphoid system. Antibody-Mediated Immunity Antibodies Proteins known as globulins, so another name for antibodies is immunoglobulins, which have a shorthand designation Ig. The structure of an antibody determines its classification, and each class plays a special role in antibody-mediated immunity. Antibodies do not destroy pathogens directly. Antibodies form antigen-antibody complexes that mark pathogens for destruction. For example: allows for complement fixation. Antibodies also neutralize bacterial toxins by binding the antigens. Which prevents the toxins from attaching to receptors of body cells. Antigen-antibody complexes are engulfed and destroyed by macrophages, eosinophils, and neutrophils. Primary Immune Response Occurs with the first encounter of a pathogen or non-self antigen. Stimulates T and B cells Become activated and proliferate and make clones to destroy the antigen. Produces memory cells that recognize the same antigen if it reenters the body. Secondary Immune Response Occurs with another invasion of the same antigen. Memory T and B cells launch a more rapid and intense response than the primary immune response. Types of Immunity There is more than one way for a person to develop immunity to a particular pathogen. Mechanisms are grouped into two broad categories: 1. Active immunity Acquired through the use of a person’s immune response. Leads to the development of memory cells. 2. Passive immunity Acquired without the activation of a person’s immune response. No memory is developed. Types of Immunity Naturally acquired active immunity Results after a person is exposed to a pathogen. Person gets sick and recovers. Leaves antibodies and memory T and B cells to fight later infections via a secondary immune response if it reenters the body. Artificially acquired active immunity Person receives a vaccine of dead, weakened, or inactivated pathogens or their antigenic parts. Triggers a primary immune response that forms memory T and B cells and antibodies to fight the pathogen if it reenters the body. Booster shots cause a secondary response to boost antibody levels. This Photo by Unknown Author is licensed under CC BY-NC-ND Types of Immunity Naturally acquired passive immunity Infants receive maternal antibodies IgG through placenta and IgA in breast milk. Artificially acquired passive immunity Receiving injections of antibodies produced by another person, animal, or synthetically. Called antiserum Used in emergency situations when the pathogen acts too severely and quickly. Rejection of Organ Transplants Organ transplants are viable treatment options for persons with a terminal disease of certain organs such as the heart, kidneys, and liver. Major challenge after transplant is organ rejection. The lymphoid system recognizes the new organ as non-self and attacks it. To limit chance of rejection Determine compatibility of donor and recipient tissues. Compare human leukocyte antigens (HLAs) group A. The closer to 100% the better the chance of avoiding rejection. Rejection of Organ Transplants To limit chance of rejection Immunosuppressive therapy is administered: The lymphoid system must be suppressed sufficiently to prevent rejection of the organ but not enough to eliminate immunity against pathogens. Cyclosporine inhibits T cell activity with minimal B cell effects. T cells are primarily responsible for organ rejection. B cells are still able to provide antibody-mediated immunity against pathogens. Bacterial and viral infections are primary causes of death among transplant recipients. Cancer risks are also increased. Disorders can be grouped as: Infectious disorders Noninfectious disorders Infectious Disorders: Acquired immunodeficiency syndrome (AIDS) Caused by the human immunodeficiency virus (HIV) Attacks and kills TH cells. Invades macrophages, which serve as a reservoir for the virus. Immune defenses in the individual decrease. Leads to development of secondary diseases that ultimately lead to death: Kaposi sarcoma-cancer No cure but there are drugs that slow disease progression. Transmission occurs by: (does not occur through tears or saliva) Sexual intercourse→ vaginal fluids and semen. Exchanges of blood→ needles, exposed wounds, mucous membranes. Childbirth→ infected mothers may transmit HIV to infants during childbirth. Kaposi Sarcoma https://www.nature.c om/articles/d41586023-00479-2 Infectious Disorders: Elephantiasis Tropical disease spread by bites of certain mosquito species. Characterized by greatly swollen (edematous) lower limbs or other body parts. Lymphatic vessels are blocked by round worms. Fluid accumulates in tissues drained by the plugged lymphatic vessels. Lymphadenitis Inflammation of the lymph nodes. “swollen glands” Common complication of bacterial infections. Bubo → a severe swollen lymph node. Noninfectious Disorders Allergy or hypersensitivity: Abnormally intense immune response to an antigen harmless to most people. Such antigens are called allergens. Sometimes allergies are triggered by a combination of environmental factors rather than by an identifiable allergen. Such cases are difficult to treat because most drugs don’t work against these types of reactions. Sensitization to an allergen results in reactions whenever exposure occurs. Reactions can be immediate or delayed. Noninfectious Disorders Allergy or hypersensitivity: Occur when allergens bind with IgE antibodies on mast cell surfaces. Cells release histamine, which stimulates an inflammatory response. Localized reactions are unpleasant but not life threatening. E.g., hay fever, hives, allergy-based asthma, and digestive disorders. Systemic reactions (anaphylaxis) are life threatening. Impair breathing and cause circulatory failure due to a sudden drop in pressure as blood vessels dilate and fluid moves into the tissues. E.g., bee stings and penicillin. Delayed reactions Appear 1 to 3 days after antigen exposure. Due to cytokines from T cells. E.g., poison ivy Noninfectious Disorders Autoimmune diseases: T and B cells recognize body tissues as non-self. Produces an immune response. Due possibly to change in body molecules are no longer recognizable as self. E.g., rheumatoid arthritis, which destroys joints and type I diabetes, which destroys beta cells in the pancreas. Lymphoma: Any tumor of lymphoid tissue. Hodgkin lymphoma: Malignant lymphoma, which is cancer of lymphoid tissue involving the production of B cells. Enlarged and painless lymph nodes (lymphadenitis), fatigue, fever, night sweats. Early treatment with chemotherapy and radiation yields a high cure rate. Noninfectious Disorders Severe combined immunodeficiency (SCID): Group of disorders resulting from several different genetic defects: Marked deficit or absence of both T and B cells. Lymphoid system is basically nonfunctional. Infants have little or no protection against pathogens and usually die within one year. Stem cell transplants form the red bone marrow David was born in 1971 with severe combined or umbilical cord blood and gene therapy have immunodeficiency (SCID), and was forced to live been successful in some cases. in a specially constructed sterile plastic bubble from birth until he died at age 12. https://youtu.be/yLqhEZKxsoo