In serology, a change in antibody titer is a central concept for the diagnosis and monitoring of disease progression. The titer of antibody is the reciprocal of the highest dilution of the patient’s serum in which the antibody is still detectable. Patients with large amounts of antibody have high titers, because antibody is still detectable at very high dilutions of serum. Serum for antibody levels should be drawn during the acute phase of the disease (when it is first discovered or suspected) and again during convalescence (usually at least 2 weeks later). These specimens are called acute and convalescent sera. For some infections, such as legionnaires’ disease and hepatitis, titers may not rise until months after the acute infection, or they may never rise. Therefore, changes in titer must be carefully correlated with the patient’s signs and symptoms of the specific disease or suspected infectious agent.

Patients with intact humoral immunity develop increasing amounts of antibody to a pathogen over several weeks. If it is the patient’s first exposure to the pathogenic organism and the specimen has been obtained early enough, no or very low titers of antibody are detected at the onset of disease. In the case of a second exposure, the patient’s serum usually contains measurable antibody during the initial phase of the disease, and the antibody level quickly increases as a result of the anamnestic response. For most pathogens, an increase in the patient’s titer of two doubling dilutions (e.g., from a positive result of 1 : 8 to a positive result of 1 : 32) is considered to be diagnostic of current infection. This is defined as a fourfold rise in titer.

For many infections, accurate results used for diagnosis are achieved when acute and convalescent sera are tested concurrently in the same test system. Variables inherent in the procedures and laboratory error can cause a difference of one doubling (or twofold) dilution in the results obtained from a same sample tested con currently in different laboratories. Unfortunately, a certain proportion of infected patients never demonstrate a rise in titer, necessitating the use of other diagnostic tests. Because the delay inherent in testing paired acute and convalescent sera results in diagnostic information arriving too late to affect the initial therapy, increasing numbers of early (IgM) serologic testing assays are being commercially evaluated. Moreover, it is sometimes more realistic to see a fourfold fall in titer between acute and convalescent sera when samples are tested concurrently in the same system. This is a result of the sera being collected late in the course of an infection, when anti bodies have already begun to decrease.

اخر الاخبار

اخبار العتبة العباسية المقدسة

الهيأة العليا وجمعية العميد تعقدان اجتماعا لمناقشة آليات التعاون العلمي المشترك

لتقديم الدعم النفسي والمعنوي قسم الشؤون الطبية يزور أطفال مرضى السرطان في مستشفى الإمام الحسن (عليه السلام)

قسم الشؤون الفكرية يهدي إصداراته الحديثة إلى مكاتب المراجع وعدد من المؤسسات في بابل

عبر مركز الكفيل للصحة والسلامة.. قسم الشؤون الطبية يستأنف ورش الإسعافات الأوّلية للمنتسبين

المزيد

الآخبار الصحية

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عوامل خفية تسرّع شيخوخة الدماغ

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المزيد

الآخبار التكنلوجية

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رواد "أرتيميس 2" يكشفون تفاصيل حياتهم في الفضاء

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روسيا تطلق صاروخ "سويوز-2.1 إيه" من قاعدة بليسيتسك الفضائية

المزيد

مواضيع ذات صلة

Features of the Humoral Immune Response Useful in Diagnostic Testing

Enzyme Immunoassays

Immunofluorescent assays

Particle Agglutination

Precipitation Tests

Production of Antibodies for use in Laboratory Testing

Investigation of Strain Relatedness/Pulsed-Field Gel Electrophoresis

Detection of Antimicrobial Resistance

The Light Microscope

Identification of Microorganisms Grown in Culture

Direct Detection of Microorganisms

Laboratory Manifestations of Iron Overload