Diagnose the allergy at home:(Protein microarray)

Principle of protein array

The mechanism of the protein microarray was the same as the immunostaining. It utilized the specific binding between the receptor to antigen or cell surface marker. The following figure showes several examples that protein microarray could be used.

Types of Protein mciroarray

Three types of protein microarrays are currently used to study the biochemical activities of proteins: a.) analytical microarrays, b.) functional microarrays, and c.) reverse phase microarrays. Analytical microarrays are typically used to profile a complex mixture of proteins in order to measure binding affinities and protein expression levels of the proteins in the mixture. In this technique, a library of antibodies, aptamers, or affibodies is arrayed on a glass microscope slide. The array is then probed with a protein solution. Antibody microarrays are the most common analytical microarray .These types of microarrays can be used to monitor differential expression profiles and for clinical diagnostics.

Functional protein microarrays is different from analytical arrays. Functional protein arrays are composed of arrays containing full-length functional proteins or protein domains. These protein chips are used to study the biochemical activities of an entire proteome in a single experiment. They are used to study numerous protein interactions, such as protein-protein, protein-DNA, and protein-RNA interactions.

A third type of protein microarray, related to analytical microarrays, is known as a reverse phase protein microarray (RPA). In RPA, cells are isolated from various tissues of interest and are lysed. The lysate is arrayed onto a nitrocellulose slide using a contact pin microarrayer. The slides are then probed with antibodies against the target protein of interest, and the antibodies are typically detected with chemiluminescent, fluorescent, or colorimetric assays. Reference peptides are printed on the slides to allow for protein quantification of the sample lysates.

Eample 1: Allergen diagnosis

An allergen is a a nonparasitic antigen capable of stimulating a type I hypersensitivity reaction in atopic individuals. It would bind with the antibody or sometime evoke an immunoresponse, which could be fatal. There are houndreds of different source of allergen appeared around you. One of the most important one is the medicine for the disease treatment. Normally, people will not realize what kind of medicine are their allergen until they experience the irritation. However, with the development of the protein microarray, it become possible to screen your blood and test the reaction of different drugs to your immunosystem at home.

Eample 2: Screen a specific antigen for SARS clinical diagnosis

A study in 2005 try to utilize a protein microarray to screen the recombinant SARS-CoV antigens. It aimed to find specific antigen fragments that are of use in developing a clinical SARS antibodies testing method, such as ELISA. Reported data showed that this was a relatively high degree of sensitivity and specificity for SARS-CoV antibody testing. In addition, protein microarray assay presents a higher positive rate and sensitivity compared with the traditional ELISA screening method, and could provide a rapid, parallel and high-throughput antigen screening platform. As the specific antigen was found for the infectious disease, such as SARS, the protein microarray coating with the antigen could be use for the diagnosis the SARS in the near future.