Lymphocyte Development

pathogens target various different parts of the body, this requires many different host defence mechanisms to get rid of them
1. extracellular
  1. cytoplasmic
    1. cytotoxic T cells
    2. NK cells
  2. vesicular
    1. T-cell dependent macrophage activation
2. intracellular
  1. epithelial surfaces
    1. antibodies (IgA)
    2. antimicrobial peptides
  2. Blood, lymph, interstitial spaces
    1. antibodies
    2. complement
    3. phagocytosis
an immunogen is anything which illicts an immune response
an antigen is anything recognised by a B cell or T cell receptor
1. all immunogens are antigens but bot all antigens are immunogens
  1. hapten is an antigen but not an immunogen
2. epitopes are the immunologically active parts of an antigen
  1. antibodies can bind to the epitopes of an antigen
Lymphoid tissue
1. primary lymphoid tissue
  1. where lymphocytes are made
  2. T cells in the Thymus
    1. t cells recognise antigens using their T call receptor (TCR)
    2. the thymus involute with age
  3. B cells and NK cells in the bone marrow
    1. B is NOT for bone marrow, they were first discovered in the Bursa of Fabricius the primary lymphoid tissue for B cells in birds
    2. in mammals, B cells develop from stem cells in the bone marrow
    3. B cells become plasma cells these produce a large amount of different types of atnibodies
  4. size is antigen independent
  5. B and T cells develop from common lymphoid progenitors in the bone marrow
2. secondary lymphoid tissue
  1. where immune responses occur
  2. Lymph nodes
    1. lymphatic vessels allow fluid to drain form the tissues into lymph nodes
      1. the lymphatic system is designed to get antigens into lymph nodes where the antigens can stimulate T and B cells
    2. T and B cells reside in different parts of the lymph nodes
    3. Highly Endothelial Venule (HEV) are specialised post-capillary venous swellings that allow circulating lymphocytes to leave the blood and enter the lymphnodes
  3. spleen
    1. is the lymphoid tissue which samples antigens in the blood
    2. splenectomised individuals are more susceptible to blood infections
    3. primary follicle marginal zone Periarteriolar lymphoid sheath (PALS)
  4. tonsils
  5. Peyer's patches
  6. appendix
  7. size is antigen dependent

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Lymphocyte Development

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	Erstellt von yolajoy vor fast 12 Jahre