Anticitrullinated protein/peptide antibodies (ACPA) are highly specific for 
rheumatoid arthritis (RA). They can be found early in the disease course and are 
associated with more severe joint destruction and disease activity. In the last 
4 years, important progress has been made in the detection and identification of 
ACPA, improving antigenic composition and epitope recognition. Consequently, 
many ACPA-ELISA kits have been developed by several manufacturers and are now 
commercially available. However, albeit their widespread use in clinical 
laboratories, the use of some kits has not been accompanied by a clinical 
validation nor by a comparative evaluation of their diagnostic accuracy. In 
addition, full automation of ACPA assays featuring ease of use, rapid response, 
and high productivity is just beginning to appear on the market and also 
deserves clinical and analytical validation. This review will consider the most 
relevant characteristics of the ACPA-ELISA assays and will describe the results 
of a comparative study performed with all the currently available second- and 
third-generation commercial methods.