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Antiribosomal P Protein Antibodies in Cerebrospinal Fluid Are Associated with Neuropsychiatric Systemic Lupus Erythematosus
TAKU YOSHIO, DAISUKE HIRATA, KOICHI ONDA, HIROYUKI NARA, and SEIJI MINOTA
ABSTRACT. Methods. CSF and serum samples from 70 patients with SLE were used. Patients were divided into 4 groups: 21 patients with neurologic syndromes of the central nervous system (CNS); 19 patients with diffuse psychiatric/neuropsychological syndromes; 10 patients with complex presentations (neurologic syndromes of the CNS plus diffuse psychiatric/neuropsychological syndromes); and 20 patients without NPSLE based on diagnostic criteria for 19 NPSLE syndromes proposed by the American College of Rheumatology. IgG anti-P in CSF and serum samples were detected by Western blotting using rat liver ribosomes. Inhibition assay was performed using 5 anti-P-positive CSF samples preincubated with synthetic ribosomal P peptide. Western blotting results were compared with those from ELISA with synthetic ribosomal P peptide as antigen. The association of CSF and serum anti-P with NPSLE was analyzed. Results. CSF and serum IgG anti-P by Western blotting were detected, respectively, in 20 (28.6%) and 32 (45.7%) of 70 patients. The presence of IgG anti-P by Western blotting in the CSF was supported by positive results in the inhibition assay and significant association with CSF IgG anti-P titers by ELISA. The frequency of CSF anti-P by Western blotting in SLE patients with serum anti-P was significantly higher than in SLE patients without serum anti-P (18/32 vs 2/38; p < 0.001). The frequency of CSF anti-P by Western blotting in patients with NPSLE was significantly higher than in patients without NPSLE (19/50 vs 1/20; p < 0.01). The frequency of CSF anti-P by Western blotting in the group with complex presentations (10/10) was significantly higher than in the other 3 groups [neurologic syndromes of CNS (5/21); diffuse psychiatric/neuropsychological syndromes (4/19); and patients without NPSLE (1/20)] (p < 0.001). The frequency of serum anti-P by Western blotting in patients with NPSLE was not significantly higher than in patients without NPSLE (25/50 vs 7/20; p = 0.192). Conclusion. These results suggest that the presence of IgG anti-P in CSF of SLE patients may be involved in the appearance of NPSLE, especially in complex presentations. Measurement of IgG anti-P in CSF by Western blotting may be more useful for diagnosis of NPSLE than measurements in serum. (J Rheumatol 2005;32:34-9) Key Indexing Terms:
ANTIRIBOSOMAL P PROTEIN ANTIBODIES
From the Division of Rheumatology and Clinical Immunology and Department of Psychiatry, Jichi Medical School, Tochigi, Japan. Supported by a grant from the Ministry of Education, Science and Culture, Japan. T. Yoshio, MD, Associate Professor; D. Hirata, MD, Assistant Professor Division of Rheumatology and Clinical Immunology; K. Onda, MD, Assistant, Department of Psychiatry; H. Nara, MD, Assistant; S. Minota, MD, Professor Division of Rheumatology and Clinical Immunology. Address reprint requests to Dr. T. Yoshio, Division of Rheumatology and Clinical Immunology, Jichi Medical School, 3311 Yakushiji, Minamikawachi-machi, Tochigi-ken, 329-0498, Japan. E-mail: takuyosh@jichi.ac.jp Submitted February 20, 2004; revision accepted August 27, 2004. |