Fierz Walter
Institute for Clinical Microbiology and Immunology, St. Gallen, Switzerland.
Methods Mol Med. 2004;94:393-427. doi: 10.1385/1-59259-679-7:393.
Serological laboratory diagnosis of infectious diseases is inflicted with several kinds of basic problems. One difficulty relates to the fact that the serological diagnosis of infectious diseases is double indirect: The first indirect aim in diagnosing an infectious disease is to identify the microbial agent that caused the disease. The second indirect aim is to identify this infectious agent by measuring the patient's immune response to the potential agent. Thus, the serological test is neither measuring directly disease nor the cause of the disease, but the patient's immune system. The latter poses another type of problem, because each person's immune system is unique. The immune response to an infectious agent is usually of polyclonal nature, and the exact physicochemical properties of antibodies are unique for each clone of antibody. The clonal makeup and composition and, therefore, the way an individual's immune system sees an infectious agent, depends not only on the genetic background of the person but also on the individual experience from former encounters with various infectious agents. In consequence, the reaction of a patient's serum in an analytical system is not precisely predictable. Also, the antigenic makeup of an infectious agent is not always foreseeable. Antigenic variations leading to different serotypes is a quite common phenomenon. Altogether, these biological problems lead to complexities in selecting the appropriate tests and strategies for testing, in interpreting the results, and in standardizing serological test systems. For that reason, a close collaboration of the laboratory with the clinic is mandatory to avoid erroneous conclusions from serological test results, which might lead to wrong decisions in patient care.
传染病的血清学实验室诊断存在若干基本问题。其中一个难点在于，传染病的血清学诊断是双重间接的：诊断传染病的第一个间接目标是识别引起该疾病的微生物病原体。第二个间接目标是通过测量患者对潜在病原体的免疫反应来识别这种传染原。因此，血清学检测既不是直接检测疾病，也不是检测疾病的病因，而是检测患者的免疫系统。而这又带来了另一类问题，因为每个人的免疫系统都是独特的。对传染原的免疫反应通常具有多克隆性质，每种抗体克隆的抗体的确切物理化学性质都是独特的。克隆组成和构成，以及个体免疫系统识别传染原的方式，不仅取决于个体的遗传背景，还取决于其以往接触各种传染原的个人经历。因此，患者血清在分析系统中的反应无法精确预测。此外，传染原的抗原组成也并非总是可预见的。导致不同血清型的抗原变异是相当常见的现象。总之，这些生物学问题导致在选择合适的检测方法和检测策略、解释检测结果以及标准化血清学检测系统方面存在复杂性。因此，实验室与临床密切合作是必要的，以避免因血清学检测结果得出错误结论，从而可能导致患者护理中的错误决策。
