Antibodies to neuroblastoma cells in rheumatoid arthritis: A potential marker for neuropathy

Objective To investigate the prevalence of antibodies to neuroblastoma cell s in patients with rheumatoid arthritis (RA) complicated by peripheral neur opathy (PN), and to determine whether there is any relationship of these an tibodies with the severity of neuropathy. Methods The study was carried out on 28 patients with RA complicated by PN, 29 RA patients without PN mid 28 healthy volunteers (HV). A cell-based ELI SA method was used to test sera for the presence of IgG and IgM anti-neurob lastoma cell antibodies. Localisation and characterisation of neuroblastoma antigens recognised by patients' sera was carried out by immunofluorescent microscopy and Western blotting. Results Elevated levels of IgG anti-neuroblastoma cell antibodies were foun d in 10 (36%) neuropathic patients and in I (3%) RA control (chi(2) = 9.53, P = 0.002), while significant levels of IgM anti-neuroblastoma cell antibo dies were demonstrated in 10 (36%) neuropathic patients and in 2 (7%) RA co ntrols (chi(2) = 7.12, P = 0.008). Overall, the levels of antibodies in hea lthy volunteers were significantly lower than in RA controls and patients w ith PN. No significant relationship was found between the level of anti-neu roblastoma cell antibodies and severity of RA or neuropathy. Immunofluoresc ence staining of neuroblastoma cells with sera from 18 neuropathic patients demonstrated cytoplasmic and/or nuclear-patterns. Western blotting demonst rated reactivity with a heterogeneous group of neuroblastoma antigens. Litt le or no reactivity was seen with RA control or HV sera. Conclusion Antibodies against neuroblastoma cells are more prevalent in RA patients with peripheral neuropathy than in RA patients without peripheral nerve involvement. Such antibodies may be useful diagnostic markers for per ipheral neuropathy in RA.