IMMUNITY

• Natural immunity

  Aka Inherent/ Innate/ Non-specific immunity, something we already have in our body, mechanism of action is similar for all types of pathogens
• 2 Systems of Natural Immunity

  • External Defense System
  • Internal Defense System
• External Defense System


  • First line of defense of the body against infections or pathogens, components: physical barrier such as skin or cutaneous membrane, mucus membrane, secretions of the skin, and pH of the body fluid
• Internal Defense System

  • Second line of defense against infection or pathogens, must act quickly when the external defense system is destroyed, components: Phagocytes or WBCs and soluble substances in body fluids, promotes inflammation and phagocytosis
• Acquired Immunity


  • Third line of defense when the internal defense is not enough because the infection is too heavy
• Physical Barriers (part of external defense system)

  1. Coughing - expelling phlegm or possible antigens

  2. Sneezing - expelling antigens that are trying to enter our nasal cavity/upper respiratory tract

  3. Vomiting - expelling antigens or foreign substances that had entered our stomach
• Genetically controlled susceptibility and nonsusceptibility to certain diseases


  Example: Fy (a-b-) - resistance to malaria
• Inflammation


  A nonspecific exaggerated physiologic response which involves a vascular response and a cellular response by phagocytic cells to infection/injury, coughing, sneezing and vomiting are physiologic responses of nonspecific immunity
• Commensal microbes (normal flora)


  • Organisms that share the nutrients with the host w/o causing any disease, they are part of the innate immune system because no 2 species can occupy the same space at the same time, they can suppress the growth of pathologic microbes
• Blood type O is commonly infected by vector-borne infections such as dengue. It is inherited through codominant manner mechanism.
• Vascular Response

  • Increase blood supply (to the site of infection), increase capillary permeability caused by reaction of endothelial cells lining in the vessels
• Cellular Response

  • Neutrophils - first to migrate and the fastest to migrate to the site of inflammation, Macrophages - start to migrate about 4 hours after the onset of inflammation, their function is important when neutrophils undergo cell death
• Cardinal Signs of Inflammation


  • Redness or rubor
  • Swelling or tumor
  • Pain or dullor
  • Heat or calor
  • Diminished function or functio laesa
• Phagocytosis

  1. Initiation - through tissue damage

  2. Chemotaxis - cell movement in a certain direction under the stimulation of chemical substances

  3. Opsonization - coating of Antibody and/or complement to facilitate phagocytosis

  4. Engulfment - achieved through amoeboid motion

  5. Degranulation and digestion - through the action of hydrolytic enzymes

  6. Excretion - removal of undigested portion of the microbe
• Opsonization


  Coating of Antibody and/or complement to facilitate phagocytosis, it is not always part of phagocytosis, when present it is called indirect phagocytosis
• Nonspecific Plasma Proteins


  • Natural Antibodies - IgM, IgA
  • Lysozyme - enzyme found in many types of cells, acts as an antimicrobial agent
  • Properdin - serum protein that exerts bactericidal and virucidal effects
  • Betalysin - heat stable cationic substance with antibacterial activity
  • Complement - non-specific serum proteins that enhance the effects of antibody
  • C-Reactive Protein (CRP) - acute phase plasma protein which increases in response to inflammation and tissue necrosis
• Primary hemostasis


  sin during the activation of
• Complement

  Non-specific serum proteins that enhance the effects of antibody
• Complement is activated by antigen-antibody interaction
• When complement is present


  The activity of antibodies to destroy or eliminate an antigen is enhanced
• When complement is activated


  There is "cytolysis" - destruction of the cell membrane (always the end result)
• 1. Reactive Protein (CRP)


  Acute phase plasma protein which increases in response to inflammation and tissue necrosis
• 1. Reactive Protein (CRP)


  • It is "Non Specific", but is sensitive to Acute Stage Inflammation
  • It is NOT a good diagnostic test in the laboratory "if tested alone" - meaning it should be accompanied by other supporting tests
• Clinical Chemistry tests

  • CRP
  • CKMB (rich in heart)
  • Troponin I
• If CRP, CKMB and Troponins (specific for heart muscles) are high


  It can be correlated with AMI (Acute Myocardial Infarction)
• CRP is included in the tests because there is inflammation in AMI
• Cytokines

  Protein molecules that transmit messages between cells
• Types of Cytokines (According to Target Cell)

  • Autocrine Type - Transmit messages within cells and to other similar types of cells
  • Paracrine Type - Transmit messages to other or different types of cells
• Interferons


  Glycoproteins that have virus non-specific antiviral activity
• Interferons "interfere"


  With the viral replication process
• Three (3) Groups of Interferon (IFN) (according to the Cell that Secretes this type and the action)

  • Alpha IFN - Leukocyte Interferon, Secreted by WBC
  • Beta IFN - Epithelial Interferon, Fibroblast Interferon, Fibro-epithelial Interferon, Beta-cell Stimulating Factor II
  • Gamma IFN - Lymphokine, Most immunologically active type, Secreted by immunocompetent WBCs (T-Cells)
• Three Specific Actions of Gamma IFN

  • Immunoregulation
  • Enhances activity of NK Cells
  • Activates Macrophage
• Tumor Necrosis Factor (TNF)


  Produced mainly by Macrophage / Monocyte, Mediator of host response to Gram Negative bacteria
• Lipopolysaccharide (LPS)


  Present in Gram Negative cell wall that promotes the activity of TNF
• Interleukins


  Means of communication between leukocytes
• Different Types of Interleukins (activity and other names)

  • IL1 - Lymphocyte Activating Factor
  • IL2 - T-Cell Growth Factor, Activates Cytotoxic Killer Cells, NK Cells and Lymphokine Activated Killer (LAK) Cells
  • IL3 - Multi Colony Stimulating Factor (MCSF), Target Cells: Hematopoietic cells (stimulates hematopoietic cells)
  • IL4 - Produced by Activated T-Cells, Stimulate proliferation of B-Cells
  • IL5 - B-Cell Growth Factor, Share function with IL4
  • IL6 - Interferon Beta-2, Induces secretion of immunoglobulins and other plasma proteins
  • IL7 - Lymphopoietin 1, Stimulates the maturation of early B and T cells
  • IL8 - Monocyte-Derived Neutrophil Chemotactic Factor and Principal Inflammatory Cytokine
  • IL9 - Stimulates proliferation of T-Cells and Mast Cells
  • IL10 - Inhibits Cytokine Synthesis (Homeostasis), The only negative IL, It acts as an inhibitor to suppress further cytokine production (after sufficient production) to maintain homeostasis (balance)
  • IL11 - Regulates Hematopoiesis
  • IL12 - NK Cell Stimulating Factor, Enhances the activity of Cytotoxic Effector T-Cells
• Acquired Immunity

  Specific/ Adaptive Immunity
• Types of Acquired Immunity: How do we acquire ACQUIRED IMMUNITY?

  • Active: Result of actual infections (or inoculation of antigen) that causes production of antibodies
  • Passive: Result of transmission of actual antibodies
• Active Acquired Immunity

  • Artificial active - Immunization / Vaccination, The antigen is laboratory synthesized, and introduced to the patient (through subcutaneous/ intramuscular injection)
  • Natural active - Through recovery from disease (convalescence period)
• Blood Donation Screening - There are deferrals from donors who had recently received vaccines