Anti-NuMA antibodies: an uncommon specificity in scleroderma sera.

BACKGROUND

Serum antibodies in scleroderma patients are generally directed against the nucleolus and centromeres. A small proportion of patients have serum antibodies to the centrioles and mitotic apparatus.

OBJECTIVE

To determine the prevalence of serum autoantibodies against the mitotic apparatus in scleroderma patients.

MATERIAL AND METHODS

Sera from 113 patients with various forms of scleroderma were tested for antinuclear antibodies by indirect immunofluorescence on HEp-2 cells. The specificity of the antibodies was determined by Western blot.

RESULTS

Only two scleroderma sera recognized the mitotic apparatus. Western blot results showed that in both cases the target was an about 235 kDa protein corresponding to the NuMA determinant. Affinity-purified anti-NuMa antibodies were used to perform immunolocalization in synchronized HEp-2 cells using scanning laser confocal microscopy. The anti-NuMA autoantibodies recognized the mitotic asters but neither the centrioles nor the microtubules.

CONCLUSION

Our data suggest that anti-NuMA autoantibodies may be devoid of clinical significance in scleroderma. However, they remain useful as probes in cell biology studies.