Autoantibodies against Cajal bodies in systemic lupus erythematosus

Cajal bodies (CB) are distinct sub-nuclear domains rich in small nuclear ribonucleoprotein particles (snRNPs); they are involved in pre-mRNA processing. Lupus erythematosus (SLE) is an autoimmune disease characterized by autoantibody production against different nuclear molecules, including those involved in pre-mRNA processing. The aim of the present investigation is to assess the presence of anti-CB autoantibodies in a cohort of SLE sera.

Antinuclear antibodies (ANA) were screened by indirect immunofluorescence in a batch of 190 sera from patients who met the ACR criteria for SLE classification; fine specificity was determined by Western blot using HEp-2 cells or rat hepatocyte extracts purified by ion exchange chromatography.

Four sera had anti-Cajal body (CB) autoantibodies. Interestingly, all of these patients had intermittent extensive oral and esophageal ulceration. The autoantibodies to CB were of the IgG class, and by Western blot these sera had reactivity against an 80 kDa protein (coilin) associated with Sm proteins.

Anti-CB autoantibodies constitute an uncommon specificity of SLE; therefore it seems that anti-CB antibody specificity is associated with extensive mucous ulceration.