The presence of autoantibodies in the serum of patients is a very typical phenomenon for autoimmune diseases. Most of these autoantibodies, however, can also be detected in patients with other conditions and are therefore not specific. A typical example is the rheumatoid factor (RF), which is present in most inflammatory conditions. However, in some cases, autoantibodies can give the clinician a more precise indication of the type of underlying disease because they occur specifically in a certain disease. For example, anti-Sm antibodies are linked almost exclusively to systemic lupus erythematosus (SLE); whereas anti-DNA topoisomerase-I antibodies are typically present in scleroderma patients. Among the most disease-specific autoantibodies described are the so-called ACPA (anti-citrullinated protein/peptide antibodies). These antibodies occur specifically in RA and can be measured most conveniently via the anti-CCP (anti-cyclic citrullinated peptide) antibody test. 1 The CCP2 Test is Sensitive and Highly Specific for RA 1 2 3 4 5 Table 1 Cumulative anti-CCP2 diagnostic data published between 2002 and 2006 Patient group Number CCP2+ Sensitivity (%) Specificity (%) RA total 14,183 10,135 71.5   Early 3,876 2,365 61.0   Established 10,307 7,770 75.4  Controls 15,156 683 4.5 95.6  Non-RA 11,502 647 5.6 94.4  Healthy 3,654 36 1.0 99.0 In total, 122 independent studies were included. The selection for early RA has been adopted from the original reports. 6 7 8 9 10 11 same 10 7 7 11 11 12 13 14 15 16 14 Anti-CCP2 Antibodies are Present Early in Disease and have Predictive Potential 2 EULAR recommendations for the management of early arthritis 16 17 18 19 16 20 21 22 23 24 22 25 26 27 28 29 30 Conclusions and Future Perspectives 31