Specimen Information

Type

Gold, SST

Volume

1.0 ml

Transport Info

Refrigerated

Fasting Required?

False

Clinical Significance

Autoantibodies reacting with cytoplasmic ribosomes are highly specific for systemic lupus erythematosus. Ribosomal-P antibodies are found in approximately 12% of patients with systemic lupus erythematosus (SLE) and in 90% of patients with lupus psychosis; titers often increase more than fivefold during and before active phases of psychosis.

Researchers discovered autoantibodies against cytoplasmic ribosomes in patients with systemic lupus erythematosus (SLE) in the late 1970s, but it would almost be a decade later before researchers noted their association with SLE patients who were experiencing neuropsychiatric manifestations. Using immunofluorescence with a human epithelial cell substrate, ribosome antibodies produce a finely granular cytoplasmic fluorescence. Autoantibodies reacting against cytoplasmic ribosomes are highly specific for SLE and, as with antibodies to Sm and dsDNA, are considered marker antibodies. Ribosome P antibodies are found in approximately 12 percent of patients with SLE and in 90 percent of patients with lupus psychosis. Most patients with both lupus psychosis and ribosome antibodies have an increase in titers more than fivefold during and before active phases of the disease. Patients with IgG levels of less than 20 units are considered to be negative for ribosome P antibody, but these antibodies are not found in all SLE patients. Patients with IgG levels of greater than 20 units are considered to be positive for ribosome P antibody. Not all SLE patients with neuropsychiatric involvement will be positive for ribosome P antibodies. Ribosome P antibodies increase and decrease during flares and remissions and titers are affected by therapy. Other marker autoantibodies for SLE include anti-Sm and anti-dsDNA. Ribosome P antibody is directed to three phosphoproteins, P0, P1, and P2, which are located on the larger 60S subunit of eukaryotic ribosomes. Recently, the ribosomal antigen has been very well characterized and studies have been published using either recombinant ribosome P or a synthetic carboxyl-terminal 22 amino acid peptide. This linear determinant peptide is common to and is the major epitope of the three ribosome phosphoproteins. Test results in and of themselves are not diagnostic. Assay results are to be interpreted in conjunction with other laboratory tests as well as the clinical presentation of the patient.