A seroimmunological profile of erosive hand osteoarthritis

Objectives: Erosive hand osteoarthritis (EHOA) is an inflammatory disorder involving joints of the hands, which may be accompanied by acute phase reactants. The relationship between EHOA and classical osteoarthritis (OA) is still controversial, since some authors consider EHOA as a distinct disease, other as a subset of OA, and some as a border entity between OA and rheumatoid arthritis (RA). Scarce data are available about the seroimmunological profile of the disease, which could aid to identify a possible role of the immune system in EHOA pathogenesis, and could also allow to better differentiate EHOA both from OA and RA. Material and methods: Blood was drawn from the following patients: 37 with EHOA, 35 with OA and 45 with RA. All sera were tested for rheumatoid factor, anti-cyclic citrullinated peptide antibodies (anti-CCP), antinuclear antibodies (ANA), anti-extractable nuclear antigens (anti-ENA) and anti-neutrophil cytoplasmic antibodies (ANCA). Results: ANCA were never detected in OA, whereas they were found in 7(19%) EHOA and 8(18%) RA patients; the difference between EHOA and OA was statistically significant (p<0.01). Anti-CCP antibodies, which were consistently negative in OA, were positive in 2 EHOA (5%) at a low titre and in 23 (51%) RA patients, usually at a very high titre. The difference between EHOA and OA was not statistically significant, while the number of RA positive patients was significantly higher (p<0.001). Conclusions: Our findings suggest that the seroimmunological profile of EHOA is different from that of OA. In EHOA patients ANCA and anti-CCP antibodies might be either markers of inflammation involving neutrophils and/or markers of an underlying autoimmune process.