It is a technique similar to ELISA, but differs by some important features:

- Fluorescent dye is used instead of enzyme for labeling of antibody It detects cell surface antigens.

- It is also used to detect antibodies bound to cell surface antigens, unlike ELISA which detects free antigen or antibody.

Principle

Fluorescence refers to absorbing high energy-shorter wavelength ultraviolet light rays by the fluorescent compounds and in turn emitting visible light rays with a low energy-longer wavelength.

- The fluorescent dye is used to conjugate the antibody and such labeled antibody can be used to detect the antigens or antigen–antibody complexes on the cell surface

- The fluorescent compounds commonly used is fluorescein isothiocyanate (FITC).

Types

Direct Immunofluorescence Assay

 Step 1: Sample containing cells carrying surface antigens is smeared on a slide

Step 2: Primary antibody specific to the antigen, tagged with fluorescent dye is added

Step 3: Slide is washed to remove the unbound antibodies and then viewed under a fluorescence microscope (Fig. 1A).

Fig1. A and B: Immunofluorescence assay: A. Direct; B. Indirect.

Indirect Immunofluorescence Assay

 This detects antibodies in sample. Slides smeared with cells carrying known antigens are commercially available.

Step 1: Test serum containing primary antibody is added to the slide

Step 2: Slide is washed to remove the unbound antibodies. A secondary antibody (antihuman antibody conjugated with fluorescent dye) is added Step

 3: Slide is washed and then viewed under a fluorescence microscope (Fig. 1B).

Applications: Immunofluorescence assay has various applications, such as:

- Detection of autoantibodies (e.g. antinuclear antibody) in autoimmune diseases

- Detecting microbial antigens, e.g. rabies antigen in corneal smear

- Detection of viral antigens in cell lines inoculated with the specimens.

Flow Cytometry

 Flow cytometry is a laser-based technology that quantitatively analyses and separates the cells as they pass through the laser beam. Flow cytometry can be used to analyze multiple parameters of cells (e.g. leukocytes) such as cell counting, cell sorting, analysis of size, shape, granularity, DNA or RNA content of a cell, etc. Important applications include:

- CD4 T cell count in HIV infected patients

- Detection of leukocytes with specific markers for the diagnosis of various lymphomas.

اخر الاخبار

اخبار العتبة العباسية المقدسة

قسم الصيانة ينفذ أعمال إدامة لإحدى المدارس في محافظة النجف الأشرف

المجمع العلمي يستأنف الختمة القرآنية الأسبوعية في محافظة الديوانية

حملة تطوير وتأهيل تشهدها مدينة الفردوس الترفيهية استعدادًا لاستقبال العوائل

العتبة العباسية المقدسة تطلق فعاليات مهرجان (ترتيل الرأس) السنوي الثاني في بغداد

المزيد

الآخبار الصحية

لون أسنانك يتحدث عن صحتك.. إليك ما يقول

عادة يومية بسيطة تخفض الكوليسترول وتحمي القلب

الزنجبيل.. دواء سحري لحماية القلب

المشروبات شديدة السخونة.. "خطر خفي" يهدد صحتك

المزيد

الآخبار التكنلوجية

كيف يمكن لعادات القيادة السيئة أن تؤثر على قيمة سيارتك

في طوفان الذكاء الاصطناعي.. نصائح لحجز "تذكرة النجاة"

هكذا يسرق "قراصنة الذكاء الاصطناعي" المليارات بطرق بسيطة

فيديو لانفجار كرة نارية في سماء اليابان.. ما تفسير ذلك؟

المزيد

مواضيع ذات صلة

NGAL

Biomarkers of Tubulo-Interstitial Injury

Low-Molecular-Weight Plasma Proteins

Enzyme-Linked Fluorescent Assay (ELFA)

Diagnostic Evaluation of Lyme disease

red blood cell count (RBC count, Erythrocyte count)

rabies-neutralizing antibody test

prothrombin time (PT, Protime, International normalized ratio [INR])

Estimation of the Glomerular Filtration Rate by Equations

Creatinine test for Diagnosis of Kidney Diseases

Urea test for Diagnosis of Kidney Diseases

Standard Urine Test for Diagnosis of Kidney Diseases