2 免疫细胞与免疫器官 Cells and organs of the immune system

表 2-1 外周血中各种白细胞的比例 免疫 细胞 占白细胞总数百分比（ % ） 中性粒 嗜碱性粒细胞 0.1 嗜酸性粒细胞 1-7 单核细胞 2-11 淋巴细胞 树突细胞 一 Cells of the Immune System ( 免疫细胞 )

2-1 造血干细胞 的分化途径 Differentiation of hematopoietic stem cells

2-2 粒细胞系 (Granulocytes) 中性粒细胞 嗜酸性粒细胞 嗜碱性粒细胞

中性粒细胞 (Neutrophil) 在普通光学显微镜下观察 Giemsa 染色血涂片，中性粒细胞 呈淡藕荷色，多叶核，胞浆中含有大量的细胞颗粒。透射 电镜下其胞浆颗粒清晰可辨。

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.

嗜酸性粒细胞 (Eosinophil) 在普通光学显微镜下观察 Giemsa 染色的血涂片，嗜酸性粒 细胞胞核为双叶状，胞浆中含有大量深红色细胞颗粒。透射 电镜下其胞浆颗粒呈结晶状。

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.

嗜碱性粒细胞 (Basophil) 在普通光学显微镜下观察 Giemsa 染色的血涂片，嗜碱性 粒细胞胞浆中布满深蓝色细胞颗粒。透射电镜下胞浆颗 粒中充满致密物质。

静息肥大细胞激活后 5 分钟激活后 60 分钟

肥大细胞 (mast cell) 组织中的肥大细胞含有大量致密细胞颗粒（左）。 Crohn 氏病患者肠粘膜组织的肥大细胞自发释放颗粒的 内容物，留下许多细胞颗粒空穴（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.

2-3Dendritic cells ( 树突细胞 ) 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 郎格汉斯细胞 (Langerhan ’ s cells) 上皮组织中的 LC （ 1 ，普通光镜）捕捉外来抗原后即进入引流淋 巴结的 T 细胞区，成为 IDC （ 2 ，扫描电镜照片）。

2 并指状树突细胞（ interdigitating DC ） IDC 表达高水平的 II 类 MHC 分子和共刺激分子 B7 ，具有激活 T 细胞的能 力。

B cells FDC 3 滤泡树突细胞（ folicular DC, FDC ） 淋巴滤泡内的 FDC 通过 Fc 受 体和补体受体捕 获被致敏的抗原， 并将其递呈给 B 细胞

2-4 单核巨噬细胞 （ monocytes and macrophages ）

单 核 巨 噬 细 胞 单核细胞体积较大，蹄状核（左，普通光镜）。透射电镜 显示其高尔基体发达、粒体丰富、胞浆颗粒明显（中）。 扫描电镜显示腹腔巨噬细胞粘附于玻璃表面（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 （淋巴细胞） 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.

淋巴细胞 (lymphocytes) 未活化淋巴细胞直径 6 ~ 7 微米，浆 / 核比例很小（左，普通 光镜）。投射电镜显示未活化淋巴细胞胞核致密，胞浆中 细胞器很少（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.

NK

T 淋巴细胞

MHC/ 抗原肽 补体 运铁蛋白 TCR CD35 CD28 B7-2 CD4 CD8 MHC-II/I IL-2 CD71 CD58 （ LAF-3 ） CD2 or Fc  R Fc  R 抗体 T 细 胞 表 面 受 体 组织胺

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  -TCR, small percentage have  -TCR.

B 淋巴细胞

抗原 补体 (C3bi ) CD23 CD28 B7-2 CD40 IL-5 Fc  R B 细 胞 表 面 受 体 IL-2 IgM IgE CD21 IL-4 CD32 IgG 补体 (C3b,C4b ) CD40-L

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 细胞 )

NK cells are large granular non-T non-B lymphocytes. NK cells are important in innate immunity to viruses and other intracellular pathogens, as well as in antibody-dependent cell mediated cytotoxicity. They also kill certain tumor cells.