Immunity

• Tolerance is the bodies ability to differentiate one's self from foreign bodies
• Immunity is the body's ability to protect itself from invasion of pathogenic agents and provide defense against harmful effects
• There are two type of immunity: Specific and non specific
• Non-specific immunity is the bodies natural or innate immunity
• Non-specific immunity is already prsent at birth and has a standardized manner of responding to antigens
• Specific immunity is called acquired or adaptive immunity.
• Activation of specific immunity leads to the formation of antibodies and sensitized T-cells
• Specific immunity has two distinct characteristics: Specificity and memory
• Specifity of the Specific immunity is due to the Lymphocytes
• There are two types of specific immunity: Active and Passive
• Active immunity is when an individual is given an antigen and it is acquired either Natural or artificial: Natural if it is acquired from a natural infection Artificial if it is acquired from a vaccine.
• Passive immunity is where an individual is given antibodies. And Passive immunity is either Artificial or natural. Artificial if it is given thru immunization and natural if it is acquired from the mother
• The first line and second line of immune defense are the non specific immunity.
• The first line of defense is composed of the skin, Mucous membranes and Secretions.
• The second line of defense are composed of, Inflammation, phagocytes, and non specific humoral factors.
• The third line of defense are composed of the specific immunity. And under this are the lympocytes and antibodies.
• Self-sterilization by dessication, desquamation, pH and fatty acid secretion
• There are some individuals that has a genetic make up that makes them resistant to some pathogens. Example of this are P. Knowlesi and P. Vivax cannot effect Duffy negative individuals.
• Second line of Immune Defense is inflammation. It is caused by the leukocytes and non specific humoral factors.
• Inflammation is the body's natural response to injury or infection.
• Phases of Inflammation incluedes

  1. Vascular
  2. Cellular
  3. Resolution and Repair
• Cardinal Signs of Inflammation

  1. Rubor - Redness
  2. Calor - heat
  3. Tumor - swelling
  4. Dolor - pain
  5. Functio laesa - diminished function
• Neutrophils are also known as polymorphonuclear leukocytes or segmenters (segs).
• Neutrophils composed of 50 to 75% of the pheripheral WBCs in adults while the predominant WBCs in children are lympocytes.
• Neutrophils are associated with acute bacterial infection and extracellular pathogens.
• Eosinophils are associated with parasitic and allergic reaction regulation. They can neutralize basophils and mast cell products. And they use cationic proteins that kills parasitic organisms.
• Basophils are the smallest granulocyte and are inflammatory mediators in the blood. They are also associated with malignancy.
• Monocytes are the largest cell in the peripheral blood and has a horse shoe nucleus with a ground glass cytoplasm. Monocytes are inactive Macrophages and they stay in the blood for 30 hours, and migrate to tissues.
• Macrophages are from Monocytes. Macrophages are named after which cell they migrate to. And they Have important roles in both Specific and non specific response. Macrophages are antigen-presenting cells.
• Mast Cells are inflammatory cells tissues and are involed in involved in allergic reactions; may

  function as Antigen-Presenting cells.
• Dendritic cells are effective Antigen-Presenting Cells. They Capture antigens through phagocytosis or endocytosis then presents it to T cells to initiate the specific immune response. Dentritic cells are the most potent Phagocytic cells.
• Neutrophils perform phagocytosis in acute inflammation while Macrophages perform phagocytosis in chronic inflammations.
• Types of Phagocytosis

  1. Direct
  2. Indirect
• Direct Phagocytosis happens if the phagocyte recognizes pathogen with their PAMP thru Pathogen Recognition Receptors (PRRs).
• Indirect Phagocytosis happens when the phagocytic cells recognizes the pathogen only after it is coated with opsonins. Pathogens are coated with opsonins by complement proteins. Indirect Phagocytosis is faster compared to direct.
• Pathogen Recognition Receptors are Molecules on host cells that recognize substances found only on pathogens. PRRs allows host cells to distinguish self from nonself.
• PRRs can be found on neutrophils, monocytes,

  eosinophils, mast cells, and dendritic cells.
• Pathogen Associated Molecular Patterns ( PAMP) are molecules found only on pathogens; recognized by PRRs
• Opsonins are serum proteins that attach to a foreign

  cell or pathogen and help speed up

  phagocytosis
• Chemotaxis is the movement of phagocytes towards the source of chemoattractants