2免疫細胞與免疫器官,Cells and organs of the immune system,一 Cells of the Immune System (免疫細胞),2-1 造血干細胞的分化途徑 Differentiation of hematopoietic stem cells,2-2 粒細胞系 (Granulocytes),中性粒細胞,嗜酸性粒細胞,嗜堿性粒細胞,中性粒細胞 (Neutrophil),在普通光學顯微鏡下觀察Giemsa染色血涂片，中性粒細胞呈淡藕荷色，多葉核，胞漿中含有大量的細胞顆粒。透射電鏡下其胞漿顆粒清晰可辨。,RBC,Neutrophils represent 60-70% of leukocytes in the peripheral blood. Their granules contain alkaline phosphatase, lysozame, lactoferrin etc.,They are the earliest phagocytic cells to appear in the bacterial infection and are prominent constituent of pus.,嗜酸性粒細胞 (Eosinophil),在普通光學顯微鏡下觀察Giemsa 染色的血涂片，嗜酸性粒細胞胞核為雙葉狀，胞漿中含有大量深紅色細胞顆粒。透射電鏡下其胞漿顆粒呈結晶狀。,Eosinophils represent 2-4% of peripheral blood white cells. Their granules contain histaminase, acid phosphatase, and major basic protein. They are important in destroying parasites, phagocytosing Ag-bound complexes, and combating histamine levels during allergic reaction.,嗜堿性粒細胞 (Basophil),在普通光學顯微鏡下觀察Giemsa染色的血涂片，嗜堿性粒細胞胞漿中布滿深藍色細胞顆粒。透射電鏡下胞漿顆粒中充滿致密物質。,靜息肥大細胞,激活后 5 分鐘,激活后 60 分鐘,肥大細胞 (mast cell),組織中的肥大細胞含有大量致密細胞顆粒（左）。Crohn氏病患者腸粘膜組織的肥大細胞自發釋放顆粒的內容物，留下許多細胞顆粒空穴（右）。,Basophils represent 1% of peripheral blood white cells. Their granules contain histamine, heparin, and chemotactic factors for neutrophils and eosinophils. They are similar to mast cells in that they participate in IgE-mediated hypersensitive responses.,2-3 Dendritic cells (樹突細胞),Dendritic cells are bone marrow-derived cells specialized to present antigen to B or T cells in order to initiate a primary immune response.,1 郎格漢斯細胞 (Langerhans cells),上皮組織中的LC（1，普通光鏡）捕捉外來抗原后即進入引流淋巴結的T細胞區，成為IDC（2，掃描電鏡照片）。,2 并指狀樹突細胞（interdigitating DC）,IDC表達高水平的II類MHC分子和共刺激分子B7，具有激活T細胞的能力。,B cells,FDC,3 濾泡樹突細胞（folicular DC, FDC）,淋巴濾泡內的FDC通過Fc受體和補體受體捕獲被致敏的抗原，并將其遞呈給B細胞,2-4 單核巨噬細胞,（monocytes and macrophages）,單核細胞體積較大，蹄狀核（左，普通光鏡）。透射電鏡顯示其高爾基體發達、粒體豐富、胞漿顆粒明顯（中）。掃描電鏡顯示腹腔巨噬細胞粘附于玻璃表面（右）。,Monocytes have numerous lysosomes in their cytoplasm and can readily leave the circulation to give rise to macrophages within almost every organ. They are even more phogocytic than neutrophils in that they can degrade larger bacteria within lysosome.,2-4 Lymphocytes（淋巴細胞）,Lymphocytes are a class of white blood cells that bear variable cell surface receptors for antigens. There are two main classes of lymphocytes- B and T cells-which mediate humoral and cellular immunity respectively.,淋巴細胞 (lymphocytes),未活化淋巴細胞直徑67微米，漿/核比例很小（左，普通光鏡）。投射電鏡顯示未活化淋巴細胞胞核致密，胞漿中細胞器很少（右）。,Resting lymphocytes have little cytoplasm and condensed nuclear chromatin. Upon activation, the cell enlarges to form a lymphoblast and then proliferates and differentiates into an antigen-specific effector cell.,T 淋巴細胞,MHC/抗原肽,補體,運鐵蛋白,TCR,CD35,CD28,B7-2,CD4,CD8,MHC-II/I,IL-2,CD71,CD58（LAF-3）,CD2,or,FcmR,FcgR,抗體,T 細 胞 表 面 受 體,組織胺,T cells are a subset of lymphocytes defined by their development in the thymus and by heterodimeric receptor associated with the proteins of CD3 complex. Most T cells have ab-TCR, small percentage have gd-TCR.,B 淋巴細胞,B cell is one of the two major types of lymphocytes. The antigen receptor on of B cells is a cell-surface Ig. On activation by Ag, B cells differentiate into plasma cells producing Ab molecules of the same Ag specificity as the receptor.,Natural Killer cells (NK 細胞),NK cells are large granular non-T non-B lymphocytes. NK cells are