Latex fixation test

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Latex fixation test
MeSH D007841
MedlinePlus 003334

The latex agglutination method is used clinically in the identification and typing of many important microorganisms. These tests are based on and utilize the patient's antigen-antibody immune response. (This response occurs when the body detects a pathogen and forms an antibody specific to an identified antigen (a protein configuration) present on the surface of the pathogen.)

Agglutination tests, specific to a variety of pathogens, can be designed and manufactured for clinicians by coating latex beads with pathogen-specific antigens. In performing a test, laboratory clinicians will mix normal saline serial dilutions (important because of the prozone effect) of a patient's CSF, serum or urine with the coated latex particles and observe for agglutination. Agglutination/clumping of the beads in any of the dilutions is considered a positive result, confirming that the patient has produced the pathogen-specific antibody. [Instances of cross-reactivity can lead to confusing results.]

Agglutination techniques are used to detect antibodies produced in response to the rubella virus or to the rheumatoid factor. There is an excellent LA test for cryptococcus.[1] Agglutination techniques are also used in definitive diagnosis of Group A streptococcus.

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  1. ^ Howanitz and Howanitz, Laboratory Medicine. Published by Church Livingston; 1991: pp 825–828