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

OBJECTIVE
To investigate the prevalence of antibodies to neuroblastoma cells in patients with rheumatoid arthritis (RA) complicated by peripheral neuropathy (PN), and to determine whether there is any relationship of these antibodies with the severity of neuropathy.


METHODS
The study was carried out on 28 patients with RA complicated by PN, 29 RA patients without PN and 28 healthy volunteers (HV). A cell-based ELISA method was used to test sera for the presence of IgG and IgM anti-neuroblastoma 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 found in 10 (36%) neuropathic patients and in 1 (3%) RA control (chi 2 = 9.53, P = 0.002), while significant levels of IgM anti-neuroblastoma cell antibodies were demonstrated in 10 (36%) neuropathic patients and in 2 (7%) RA controls (chi 2 = 7.12, P = 0.008). Overall, the levels of antibodies in healthy volunteers were significantly lower than in RA controls and patients with PN. No significant relationship was found between the level of anti-neuroblastoma cell antibodies and severity of RA or neuropathy. Immunofluorescence staining of neuroblastoma cells with sera from 18 neuropathic patients demonstrated cytoplasmic and/or nuclear patterns. Western blotting demonstrated reactivity with a heterogeneous group of neuroblastoma antigens. Little 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 peripheral neuropathy in RA.