The Adaptive Immune Response “Match me perfectly and I’m neutralized” Kathy Huschle Northland Community and Technical College

Adaptive Immune Response in contrast to the innate immune response which we are basically born with, the adaptive immune response is an ever developing system it continues to mature throughout our life

Adaptive Immune Response in most cases as each new microbial invader is encountered, our adaptive immune response initiates a specific attack against the invader generally this invader is remembered and that “memory” is readily available in the case of a second or subsequent attack from the same invader

Adaptive Immune Response this system is an extremely complex system to which we will attempt to gain a basic understand immunologists are continually discovering many facts about the adaptive immune response

Adaptive Immune Response the adaptive immune response is learned or acquired recognizes specific substances foreign to the body is essential for life

Adaptive Immune Response other terms used for the adaptive immune response include acquired immunity specific immunity though at one time thought to function exclusive of the innate immune system, research is now discovering a correlation between the two systems regardless of a correlation or not, the failure of our immune system results in mortality

Adaptive Immune Response adaptive immune response is characterized by specificity memory learned ability to recognize (acquired) pathogens which allows the body to usually only suffer once from that particular pathogen

Components of the Adaptive Immune System antigens antibodies lymph system lymphocytes B cells T cells NK cell (Natural Killer) Antigen Antibody B cell T cell NK cell

Antigens the term antigen derives from the two words antibody generator most antigens are proteins or large polysaccharides

Antigens often a component of invading microbes, such as the capsule, cell wall, flagella, toxin particular chemical that will activate the adaptive immune response Antigens found in autologous tumor

Antigens invading microbes can have many antigens on its surface pathogen

Antigens two essential properties of antigens include immunogenicity the ability to stimulate immune system antigen-antibody complex

Antigens specific reactivity the ability to react with effector molecules (antibody) to form an antigen-antibody complex Antigens in red with green borders

Antibodies glycoproteins that are also referred to as immunoglobiulins basic structure is a Y shaped molecule with 2 functional parts Fab region Fc region Fab region Fc region

Antibodies Fab region this is the part of the antibody that binds to the antigen Fc region the stem of the antibody that functions as a “red flag” notifies the rest of the immune system: “here I am, come and help”

Antibodies protection gained from the formation of antigen-antibody complexes basically comes down to the tagging of foreign cells and molecules for destruction by phagocytes and complement Antibodies shown in different stains

Antibodies the antibody molecule is not damaging to the antigen Melanoma antigens

Antibodies neutralization blocks the adhesion of bacteria and viruses by bathing the surface of the cell with antibody immobilization and prevention of adherence antibodies binding to structures such as flagella and pili can interfere with mobility and attachment

Antibodies

Antibodies

Lymphoid System in regards to the immune system the lymphatic system consists of tissues and organs that are designed and located to convey the B and T cells into contact with all antigens that enter the body

Lymphoid System this process is accomplished with the lymphatic vessels fluid of the lymphoid system called lymph secondary lymph organs such as tonsils, spleen, lymph nodes

Lymphoid System primary lymph organs bone marrow: the location of stem cells that will eventually become B and T cells, B cells mature in the bone marrow thymus: maturation of the T cells Lymph node Bone marrow with leukemia Healthy bone marrow

Lymphoid System notice how completely our body is covered by the lymphoid system

Lymphocytes critical part of immune system responsible for detection of foreign antigens activate immune system B lymphocytes T lymphocytes natural killer cells (NK cells)

B lymphocytes: B cells antibody producing cells that respond to an antigen stimulation develop from stem cells located in the red bone marrow of adults and the liver of a fetus B Cells dividing

B lymphocytes: B cells following maturation, they migrate to the lymphatic tissue B cell in lymph node

B lymphocytes: B cells once in place in the lymphoid organs, the B cells recognize antigens by means of the antigen receptors found on their cell surfaces basis for antibody-mediated immunity HIV antigens in yellow B cells in red B indicates a B cell

B cells

T lymphocytes: T cells key cellular component of immunity develop from stem cells found in the bone marrow precursors to T cells migrate to the thymus, where they reach maturity human T cells

T lymphocytes: T cells following maturity, T cells migrate to various lymph organs where they await contact with antigens basis for cell-mediated immunity T cells (on left – orange, on right – gray) killing cancer cells (on left- mauve. on right – red)

T cells

Natural Killer Cells these cells are not immunologically specific they do not need to be stimulated by an antigen

Natural Killer Cells capable of destroying other cells, particularly viruses-infected cells and tumor cells also can attack large parasites

Clonal Selection of Lymphocytes speaks to the ability of B cells and T cells to differentiate to a population of cells capable of recognizing an infinite number of antigens it is estimated that the human body has approximately 1 billion B cells, yet each individual cell is only capable of recognizing and responding to one antigen B cell differentiation

Antibody-Mediated Immunity humoral or antibody-mediated immunity involves antibodies that are produced by B cells the term humoral is derived from the word “humors”, which is Latin for fluid in response to foreign antigens, the B cell is activated to produce a clone of plasma cells and memory cells plasma cells secrete antibodies memory cells recognize pathogens from previous encounters B memory cells are long lived and are ready to mount an attack the next time that specific antigen presents itself

Primary & Secondary Response The body can make low levels of soluble antibody about one week after exposure to antigen. However, a second exposure to antigen produces a much faster response, and several orders of magnitude higher levels of antibody. The ability of antibody to bind antigen also increases in the secondary response. The memory of antigen and stimulated response is the basis for vaccination

Antibody-Mediated Immunity the antigen-antibody complexes that are formed as a result of antibodies produce by B plasma cells attract phagocytes Bacteria in green

Antibody-Mediated Immunity phagocytosis destroys the pathogen and control of the disease is accomplished Bacteria

Cell-Mediated Immunity cell-mediated immunity involves specialized lymphocytes that respond to intracellular antigens T cells are responsible for managing cell-mediated immunity after maturation in the thymus, T cells differentiate into 2 groups T-cytotoxic cells and T helper cells Cytotoxic T cells Helper T cell

Cell-Mediated Immunity recognizes modified host cells (abnormal cells) cell-mediated immunity is critical to controlling infections where pathogens reproduce in human cell viruses, bacteria (rickettes), protozoa important role in recognizing and destroying abnormal cells, such as tumor cells T cells attacking cancer

Cell-Mediated Immunity T cells do not recognize free antigens, the antigen must be presented by a modified host cell augments antibody-mediated immunity eliminates cells infected with viruses antibodies can’t penetrate a virus within a host cell T cells

Cell-Mediated Immunity response to intracellular agents includes antigen presentation the antigen must be processed (degraded) and then individual peptides are displayed on the surface of a glycoprotein called a major histocompatibility complex (MHC) molecule this antigen processing is done by antigen presenting cell (APC)

Cell-Mediated Immunity cytotoxic T cells recognize the non-self cell and induce apoptosis (cell self death) in the viral infected or other microbial infected cell this process also recognizes cancer cells and destroys them unfortunately this process also recognizes and destroys non-self tissue or organ transplants

Cell-Mediated Immunity T-helper cells, often referred to as CD4 cells, are responsible for the “second opinion” in immunity T-helper cells judge the significance of the antigen presented by the antigen-presenting cells (APC)

Cell-Mediated Immunity after binding to an APC, T- helper cells secrete cytokines that activate other T cells and B cells interleukin-2 macrophage chemotactic factor migration inhibition factor macrophage activating factor macrophage colony stimulating factor

Cell-Mediated Immunity interleukin-2 stimulates the production of more T cells macrophage chemotactic factor (MCF) attracts macrophages (phagocytes) to the site of infection or abnormality migration inhibition factor (MIF) once at the infection site, MIF inhibits the macrophages from migrating elsewhere in the body T cell (yellow) attracting Macrophage (blue)

Cell-Mediated Immunity macrophage activating factor (MAF) once at the infection site, MAF alters the function of the macrophages increases their lysosomal activities increases their ability to kill Macrophage using pseudopodia to grab pathogen Macrophage ingesting bacteria

Cell-Mediated Immunity macrophage colony stimulating factor (CSF) regulates the production of macrophages at the site Macrophage and T cell Macrophage & E.coli

T-Helper Cells T helper cells also play a role in activating B cells in antibody-mediated immunity

Click icon to learn more about T-cell dependent antigens Helper T cells Click icon to learn more about T-cell dependent antigens

Overview of Antibody-Mediated Immunity initial response (bacteria with antigens enters the body) B cells recognize differentiate into plasma and memory cells memory: recurring exposures plasma produce antibodies antigen/antibody complex forms phagocytosis control of disease

Overview of Cell-Mediated modified host cell arrives T cells activated secrete cytokines increase of T cell reproduction attraction of macrophages (MCF) inhibit migration (MIF) activate phagocytosis (MAF) control of disease

Overview of Immunity

Summary