Immunoassay Classification	

	Immunoassays can be classed as two main types: competitive assays and immunometric assays, according to the reaction type and whether the antigen or the antibody is coupled to the label.
Competitive immunoassays are based on the competition between the antigen in the sample and the labelled antigen for the antibody binding sites. Polyclonal antibodies and labelled antigens are normally used for competitive assays; antigens with low molecular weight or low antigenicity are easier to measure with competitive assays.
For the measurement of larger antigens with several different antibody binding sites, the immunometric or sandwich assay technique is more often used. 

See later:
• Competitive Assays
• Immunometric Assays