Lec 2

• General Immune cells

  • Innate Immune cells
  • Adaptive Immune cells
• Innate Immune cells

  • Recognize pathogen, destroy if possible, send of cytokines, and present bits of antigen to the adaptive cells
• Adaptive Immune cells

  • Recognize the pathogens presented to them, produce antibodies, create memory cells
• ALL cells need to be in the right place at the right time
• Hematoxylin


  Binds negative (nucleic acid, macromolecules), stains purple/blue
• Eosin


  Binds positive ( molecules in cytoplasm, granules), stains pink
• Proportions of blood cells (most to least)

  • RBC
  • Platelets
  • Leukocytes
  • Neutrophil
  • Lymphocyte
  • Monocyte
  • Eosinophil
  • Basophil
• Lymphocytes

  • B cells
  • T cells
• B cells


  • Express BCRs on surface, Each naïve b cell has BCR with unique specificity, Effector B becomes a plasma cells, will secrete antibodies
• T cells

  • Start in bone marrow, move to thymus to mature, TCR will recognize antigen ( pieces of pathogen) that are being held in the MHC, CD8 = cytotoxic= MHC I (internal pathogens), CD4 = helper cells= MHC II ( external pathogens), Tc (killer) : release granules to destroy target, usually need help from CD4 t cells, Th ( helper) : provide help in form of cytokines which go and activate cells (B cells)
• Naïve lymphocytes


  • Haven't encountered antigens
• Effector lymphocytes


  • Encountered the antigen, carry out effector functions
• Memory lymphocytes


  • Encountered antigen in first response, remain dormant for many years then activated in secondary immune response ( will activate really quickly
• NK Cells

  • Cytotoxic granules, Are active and just killing until they are told not to, Receptors recognize MHC I that's what stops the NK cells
• Neutrophils


  • Antimicrobial: Phagocytes, Secretes cytokines to recruit other immune cells
• Eosinophils


  • Motile, Phagocytic (but less so), Degranulates (anti parasitic or allergies), Secretes cytokines that regulate lymphocytes
• Basophils

  NOT phagocytic

  Degranulate : release lots of histamine

  Anti parasitic and involved with allergies (inflammation)
• Mast Cells


  • Released by bone marrow, Enter many types of tissues then just waits for pathogen to come to it, Release Lots of histamine (inflammation/allergies)
• Monocytes

  • Circulate in blood, Phagocytic (ROS), Differentiate in macrophages or dendritic cells in response to infection
• Macrophages:

  Professional phagocyte: Clears damaged host cells, destroys pathogens

  Presents AG to T cells

  Has lysosome for harmful materials instead of granules
• Dendritic CellsImmature cells will grab a piece of pathogen and then mature and run away to present it to the adaptive immune system, Use MHC for presentation, Most potent APC for T cell activation
• Adaptive immunity involves lymphocytes that recognize specific antigens on pathogens through receptors called antibodies or T cell receptors.