The Antiperinuclear Factor (APF) and Antikeratin Antibodies (AKA) in Rheumatoid Arthritis

Abstract

The diagnosis of rheumatoid arthritis (RA) is first of all based on clinical manifestations. Serological support for such a diagnosis is not very well established and it is based mainly on the presence of rheumatoid factors (RF). A positive RF test has a predictive value [1] and is related to disease with a more severe outcome [2]. However, RF is also present in other (autoimmune) diseases and in control sera from healthy persons [3]. Therefore, testing for a second RA-specific antibody would be very useful, and might even be necessary for the management of seronegative RA patients.