【医学英语第3期】基础篇之免疫学（一）

词汇品茗

免疫学（Immunology）是所谓“免疫”原由拉丁字“immunis”而来，其原意为“免除税收”（exception from charges）， 也包含着“免于疫患”之意。免疫学是研究生物体对抗原物质免疫应答性及其方法的生物-医学科学。免疫应答是机体对抗原刺激的反应，也是对抗原物质进行识别和排除的一种生物学过程。

常用词素/趣味记忆

词汇拾零

案例分析

Case 1:

A 32-year-old man with AIDS presents to the ER with complaints of worsening headache, fever, and a stiff neck. Lumbar puncture is performed, and analysis reveals an elevated opening pressure, increased protein level, and decreased glucose level. Special staining of the spinal fluid reveals budding yeast. 

Ø What is the most likely diagnosis?

Cryptococcal meningitis is the most common fungal cause of meningitis and is prevalent among patients with AIDS.

Ø What laboratory tests can help confirm the diagnosis?

Serology is most commonly used. Cultured on Sabouraud agar. India ink stains the heavy polysaccharide capsule and reveals budding yeast. 

Ø What microorganism causes this disease?

Cryptococcus neoformans is heavily encapsulated yeast. It is found only as a yeast.

Ø CD4+ cell counts are typically at or below what level when infection with this microorganism occurs?

C neoformans usually infect severely lymphopenic patients with CD4+ cell counts<50 cells/mm3

Ø What is the appropriate treatment for this condition?

Not immunocompromised→amphotericin B + flucytosine

AIDS→amphotericin B + flucytosine + long term fluconazole

Ø What cerebrospinal fluid findings are expected in this condition?

Like viral meningitis, fungal meningitis has an elevated WBC count with a lymphocytic predominance. All other lab results mimic those of bacterial meningitis, like increased pressure and protein, decreased glucose.

Case 2:

A 32-year-old woman complains of severe seasonal allergies. Every year from Apr through Jul she is miserable with sneezing, nasal congestion, and watery itchy eyes. Antihistamines, nasal corticosteroids, nasal saline washes, oral montelukast, and attempts to avoid potential antigens have proven unsuccessful. She requests referral to an allergist for ‘allergy shots.’ What advice should you give her about immunotherapy (hyposensitization) for her allergic symptoms?

a. Immunotherapy is useful in asthma but not in allergic rhinitis.

b. Immunotherapy is used in allergic rhinitis because there is no risk.

c. The beneficial effect of immunotherapy goes away as soon as the shots are discontinued.

d. Immunotherapy against respiratory organisms can decrease the incidence of bacterial sinusitis.

e. Immunotherapy requires the identification of specific antigen by dermal or serum testing.

答案e 此案例为典型的过敏性鼻炎症状，且患者属于高敏体质。针对抗原的免疫治疗（脱敏治疗）可以控制严重的过敏性鼻炎，但之前必须确定过敏原。治疗需要耗费大量时间，有时患者会对注射的免疫原产生严重过敏反应，且对细菌感染相关的鼻窦炎无明显效果。

要点总结

新型隐球菌性脑膜炎

Ø 诊断：AIDS患者如发生脑膜炎症状（高热、颈项强直、皮肤瘀斑等），最常见的病原体即新型隐球菌。临床上，对于有血液、性接触史，突发罕见部位的“诡异感染”（如隐球菌脑炎、肺部的深部霉菌感染、巨细胞病毒食管炎、直肠炎等正常人极难发生的感染）患者，需高度怀疑AIDS。

Ø 病因诊断：抽取脑脊液进行血清学检查为最可靠的方法，在沙堡氏琼脂中培养，并以印度墨汁染色，可见厚荚膜包裹的出芽酵母型病菌。

Ø 患者人群：多为CD4+细胞计数<50个细胞/mm3的AIDS或接受长期免疫抑制治疗者。

Ø 治疗：常规治疗为两性霉素B+氟胞嘧啶，对于AIDS患者需长期加用氟康唑预防真菌感染。

Ø  鉴别诊断：主要是不同脑膜炎的脑脊液生化指标区别。新型隐球菌作为一种酵母菌，其脑脊液细胞类型和病毒性脑膜炎相似，主要为淋巴细胞；蛋白和糖则和细菌性脑膜炎类似，均为蛋白升高、糖下降。

Case补充词汇

Ø Cryptococcus neoformans /,krɪptə'kɑkəs ni:əu’fɑ:məns/ : crypto-隐型，coccus-球菌，neo-新，form-形态à新型隐球菌

Ø Meningitis /'mɛnɪn'dʒaɪtɪs/：menin-脑膜，itis-炎症à脑膜炎

Ø Budding yeast：出芽酵母（新型隐球菌典型形态特征）

Ø Lymphopenic /,limfəu'pi:nik/: lympho-淋巴细胞，penic-少à淋巴细胞缺乏

Ø Cerebrospinal fluid /,sɛrəbro'spaɪnl/: cerebro-脑，spinal-脊髓à脑脊液

Ø Amphotericin B /,æmfə'tɛrɪsɪn/: 两性霉素B

Ø Flucytosine /flu:sai’təusin/：flu-氟，cyto-细胞，sine-嘧啶à氟胞嘧啶

Ø Fluconazole /’flu:kʌnəzəul/：flu-氟，co-康，nazole-唑类药物à氟康唑（大扶康，治疗严重真菌感染）

Ø  Allergic rhinitis /raɪ'naɪtɪs/: rhi-鼻子，itis-炎症à过敏性鼻炎