Serologic associations of anti-cytoplasmic antibodies identified during anti-nuclear antibody testing.

Background: There are currently no guidelines concerning additional laboratory testing for specific autoantibodies among anti-nuclear antibody-negative sera with an anti-cytoplasmic staining pattern identified by indirect immunofluorescence assay. Moreover, few data are available that address this laboratory situation.

Methods: We performed specific autoantibody assays in 200 sera with an anti-nuclear antibody titer < or =1:32 and a cytoplasmic titer (undefined staining pattern) of > or =1:64, identified sequentially in the course of routine anti-nuclear antibody testing.