英文医学科普｜免疫系统
The immune system includes specialized white blood cells, called lymphocytes that adapt themselves to fight specific foreign invaders. These cells develop into two groups in the bone marrow.
From the bone marrow, one group of lymphocytes migrates to a gland called the thymus and become T lymphocytes or T cells. Within the thymus, the T cells mature under the influence of several hormones.
The T cells mature into several different types, including helper, killer and suppressor cells. T cells are responsible for cell-mediated immunity. This type of immunity becomes deficient in persons with HIV, the virus that causes AIDS, because HIV attacks and destroys helper T cells.
The other group of lymphocytes, B lymphocytes or B cells, mature and develop within the bone marrow itself. In that process, they achieve the ability to recognize specific foreign invaders. From the bone marrow, B cells migrate through the body fluids to the lymph nodes, spleen and blood. B lymphocytes provide the body with humoral immunity as they circulate in the fluids in search of specific foreign invaders to destroy.
重点词汇汇总：
lymphocyte/ˈlɪmfəsaɪt/n. [免疫] 淋巴细胞；淋巴球
gland /ɡlænd/n. 腺密封压盖
thymus /ˈθaɪməs/n. 胸腺
suppressor cells抑制细胞 /səˈpresər/
n. 抑制器；消除器；消音器
cell-mediated immunity /sel,mi:dieitid/[免疫] 细胞免疫；[免疫] 细胞介导免疫
lymph node淋巴结
spleen/spliːn/n. 脾脏；坏脾气；怒气
humoral immunity 体液免疫 /'hjʊmərəl/adj. 体液的；温性的；由体液引起的
百度翻译：
免疫系统包括专门的白细胞，称为淋巴细胞，适应特定的外来入侵者。这些细胞在骨髓中发育成两组。
从骨髓中，一组淋巴细胞迁移到称为胸腺的腺体，成为T淋巴细胞或T细胞。在胸腺内，T细胞在几种激素的影响下成熟。
T细胞成熟为几种不同类型，包括辅助细胞，杀伤细胞和抑制细胞。T细胞负责细胞介导的免疫。由于艾滋病毒攻击并破坏辅助性T细胞，这种免疫力在艾滋病病毒感染者中变得不足。
另一组淋巴细胞，B淋巴细胞或B细胞在骨髓本身内成熟并发育。在这个过程中，他们实现了识别特定外国入侵者的能力。从骨髓中，B细胞通过体液迁移到淋巴结，脾脏和血液。B淋巴细胞为身体提供体液免疫，因为它们在液体中循环以寻找特定的外来入侵者来摧毁。