For researchers using techniques such as flow cytometry, western blot, ELISA, and immunohistochemistry, antibodies are used to measure antigens in complex biological samples. It is now possible to measure hundreds of antigens simultaneously with multiplex immunoassay technology. In general, all of these antibody-based detection techniques require labelling (antibody labelling) with a description that allows them to be measured. You can visit some sites over the internet to get information on multiplex ELISA as well.
Most of the antibodies that are commercially available are not labelled, which means they cannot be measured. In general, only a small number of available antibodies in conjugated / labelled form are considered commercially valuable by antibody manufacturers. For antibodies that are available in conjugated form, this is usually the case for short-range markers. This can be very limiting in experimental designs.
The use of unlabelled antibodies presents several inherent problems, especially in multiplex tests. For indirect detection, which usually uses secondary antibodies with the required labelling, it is difficult to prepare a secondary reagent set with the desired selectivity and absence of adverse cross-reactions. However, this problem is overcome by covalently attaching labels directly to primary antibodies, reducing immunoassay complexity, and quickly and easily making antibodies ready for analysis using flow cytometry.
Historically, antibody labelling has involved chemical modification and was performed by commercial organizations with specialized knowledge of the required techniques. With significant advances in antibody labeling technology, this once difficult, time-consuming and expensive procedure can now be performed by anyone in a laboratory without requiring special training or experience.