Presentation on theme: "The Immune system. The Immune system is the body’s defense system Against: – Bacteria – Viruses – Protists – Other living invaders – Toxins – Foreign."— Presentation transcript:
The Immune system is the body’s defense system Against: – Bacteria – Viruses – Protists – Other living invaders – Toxins – Foreign debris – Cancerous cells The immune system is complex Defends against threats known and unknown
Elements of the Immune system Many lines of defense, for many kinds of threats Skin Blood Thymus Spleen Lymphatic system Mucous membranes Bone marrow
Innate vs. Adaptive immunity Innate Immunity Non-specific Defends against known invaders Skin, lysozyme Pre-existing Cannot adapt to changing threats Adaptive Immunity Mechanisms which fight specific invaders For unknown threats Responsive Requires time to build defense (days) Cannot anticipate threats Remembers previous threats
Humoral vs. Cell-mediated Immunity Cell- Mediated Immunity Live cells kill invaders Innate: Phagocytic cells (e.g. macrophages, neutrophils) Adaptive: B lymphocytes and T lymphocytes create specific responses to unique invaders Humoral immunity Proteins in blood (“humors”) Innate- complement system, clotting factors, cytokines, etc. Adaptive: Antibodies
Blood is a mixture of cells and plasma ~55% Plasma ~45% Red blood cells <1% White blood cells and platelets (“buffy coat”) Human Blood after centrifugation
Blood plasma Water Nutrients Solutes- Na+, Cl-, wastes, CO2, etc. Contains humoral immune elements Some innate immunity
All blood cells are part of the hematopoetic stem cell lineage
Hematopoetic stem cells differentiate into all blood cells Pluripotent- able to become any one of many cell types Includes T cells, B cells, macrophages, etc.
Red blood cells carry oxygen and CO2 Lose nucleus in development Short-lived, no repair Packed solid with hemoglobin Membranes designed to maximize surface area Facilitate gas transfer
Hemoglobin The oxygen-carrying protein Heterotetrameric protein 2 alpha subunits, 2 beta Each subunit holds a Heme group Each heme holds an Fe++ ion Each Fe++ can bind an O2
Hemoglobin binding curve In areas of High O2 (e.g., lungs)- binds O2 very well (picks up O2) In areas of Low O2 (e.g., muscles) binds O2 poorly (drops off O2) Myoglobin binds O2 in muscle & organ tissues
Platelets assist with blood clotting Recruit plasma protein fibrinogen to a cut They release clotting factors Clotting factors convert fibrinogen to fibrin Fibrin net prevents blood loss
The liquid part of blood is called A) water. B) plasma. C) serum. D) extrastitial fluid. E) anionic fluid.
White blood cells come in a great variety of types
Immune cells are the only cells with different DNA VDJ recombination of light and heavy chains generate antibody diversity Change is permanent A form of Russian Roulette for the cell Successful recombination creates a binding antibody- cell survives Unsuccessful- cell is destroyed Finding a good cell takes time
Bound antibodies are the mark of death for invaders
Breast milk contains maternal antibodies Infants have no acquired immunity Mother’s acquired immunity is transferred to the baby through nursing Passive immunity Is not retained by the baby
Vaccination gives the body active immunity An antigen sample is given to a person Person’s immune system mounts a response to the antigen Antigen can be deactivated/destroyed virus particles, etc. No waiting time for body to develop 2 o immune response
Antibodies can be used as therapy Some growth factors are overactive in certain cancers Antibody binds to growth factors, or their receptors
Polyclonal Antibodies From multiple B cells Bind to different epitopes of an antigen
Monoclonal antibodies Obtained from a single B cell Bind to a single epitope A single B cell is fused to a myeloma cell Myeloma cells are immortal
Mouse antibodies can be humanized Constant regions of mouse antibody are gradually replaced with human sequences
Fluorescent antibodies can be used in scientific experiments Fluorescent molecules can be linked to antibodies Antibodies show us where proteins exist in vivo
In an ELISA, Horseradish Peroxidase is linked to a 2 o antibody
Indirect ELISA To detect the presence of an antibody Wash Block Wash Substrate Primary Antibody Secondary Antibody
In Autoimmune disease, the immune system attacks the self
Allergies are immune responses to harmless antigens
A substance that can elicit an immune response is called a(n) A) complement. B) interferon. C) histamine. D) antibody. E) antigen.
Which one of the following statements about HIV is false? A) The genome of HIV consists of RNA. B) HIV attacks helper T cells. C) New HIV are produced inside helper T cells. D) HIV is transmitted by body fluids transporting infected cells. E) Some antibiotics have proven effective in combating the spread of AIDS.
Which type of immune response is always disadvantageous to a person? A) cell-mediated B) inflammatory C) humoral-mediated D) autoimmune E) All immune responses are advantageous.