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==Introduction==

==Introduction==

[[Image:763px-Cryptosporidium parvum 01.jpg|thumb|right|150px|Immunofluorescence of ''Cryptosporidium parvum'' spores]]

[[Image:763px-Cryptosporidium parvum 01.jpg|thumb|right|150px|Immunofluorescence of ''Cryptosporidium parvum'' spores, EPA/H.D.A. Lindquist, '''WikiMedia Commons''', 2006]]

Immunofluorescence is a technique used to detect cell or tissue-associated antigens using antibodies labeled with fluorescent tags. The stained tissues are then detected by immunofluorescence microscopy (qualitative) or flow cytometry (quantitative). Antibodies bind stably and specifically to their corresponding antigen and the technique makes use of the fact that they can be coupled to fluorescent dyes, such as fluorescein and rhodamine, with no effect on specificity. These conjugates bind to antigens present in a sample and can then be visualised under a microscope with a suitable light source, such as UV light.

Immunofluorescence is a technique used to detect cell or tissue-associated antigens using antibodies labeled with fluorescent tags. The stained tissues are then detected by immunofluorescence microscopy (qualitative) or flow cytometry (quantitative). Antibodies bind stably and specifically to their corresponding antigen and the technique makes use of the fact that they can be coupled to fluorescent dyes, such as fluorescein and rhodamine, with no effect on specificity. These conjugates bind to antigens present in a sample and can then be visualised under a microscope with a suitable light source, such as UV light.

==Fluorescent dyes==

==Fluorescent dyes==

If a molecule has the property of fluorescence, it can absorb light of one wavelength (excitation) and emit light of another (emission). Antibodies tagged with these dyes (known as '''fluorochromes''') form immune complexes with specific antigens which can then be indirectly visualised when excited by light of the appropriate wavelength.  

If a molecule has the property of fluorescence, it can absorb light of one wavelength (excitation) and emit light of another (emission). Antibodies tagged with these dyes (known as '''fluorochromes''') form immune complexes with specific antigens which can then be indirectly visualised when excited by light of the appropriate wavelength.  

*This detector is capable of measuring the strength of emission, so it is possible to sort cells that are negative, slightly positive and highly positive for a specific antigen

*This detector is capable of measuring the strength of emission, so it is possible to sort cells that are negative, slightly positive and highly positive for a specific antigen

*Flow cytometry provides a rapid quantitative technique for antigen detection

*Flow cytometry provides a rapid quantitative technique for antigen detection