|Values are valid only on day of printing.|
The 80S mammalian ribosome is composed of approximately equal amounts of protein and RNA. The larger 60S subunit contains 3 acidic phosphoproteins, PO, P1, and P2 with molecular masses of 38 kDa, 19 kDa, and 17 kDa, respectively. The major immunoreactive epitope of these 3 autoantigens is found within 22 consecutive amino acids of the carboxy terminus of these 3 highly conserved proteins.
It has been known for some time that sera from some patients with lupus erythematosus (LE) react with ribosomal protein antigens. Studies performed with synthetic peptide antigens revealed that reactivity detected by immunoprecipitation and by immunofluorescence methods in sera from LE patients was directed at the above mentioned epitope. Antibodies to ribosome P proteins are considered highly specific for LE, and have been reported in patients with central nervous system (CNS) involvement and so called "lupus psychosis." The reported frequency of antibodies to ribosome P protein autoantigens in patients with LE is approximately 12%.
Since patients with LE may manifest signs and symptoms of CNS diseases including neuropsychiatric symptoms, the presence of antibodies to ribosome P protein may be useful in the differential diagnosis of such patients. Other causes of CNS symptoms in patients with LE include thrombosis with or without antibodies to phospholipid antigens and iatrogenic effects from treatment with corticosteroid drugs.
As an adjunct in the evaluation of patients with lupus erythematosus (LE)
As an aid in the differential diagnosis of neuropsychiatric symptoms in patients with LE
A positive result is consistent with the diagnosis of lupus erythematosus, and may indicate the presence of central nervous system involvement.
Most patients with lupus erythematosus (LE) do not have detectable levels of antibodies to ribosome P protein.
This test should not be relied upon to establish the diagnosis or to rule out the diagnosis in a patient with signs and symptoms compatible with LE.
<1.0 U (negative)
> or =1.0 U (positive)
Reference values apply to all ages.
1. Bonfa E, Golombek SJ, Kaufman LD, et al: Association between lupus psychosis and anti-ribosomal P protein antibodies. N Engl J Med 1987;317:265-271
2. Bonfa E, Elkon KB: Clinical and serologic associations of the anti-ribosomal P protein antibody. Arthritis Rheum 1986;29:981-985