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Ann Rheum Dis. 2007 June; 66(6): 846–847.
PMCID: PMC1954662

Intrathecal immunoglobulin production in patients with systemic lupus erythematosus with neuropsychiatric manifestations

Neuropsychiatric manifestations have been reported in 30–60% of patients with systemic lupus erythematosus (SLE), with variable IgG synthesis in cerebrospinal fluid (CSF).1 In this study, we sought to examine intrathecal IgG synthesis measured qualitatively as the IgG index,2 calculated using the formula

(IgG CSF/IgG serum)/(albumin CSF/albumin serum),

and quantitatively as oligoclonal bands (OCBs) by isoelectric focusing (IEF)3 in patients with SLE with various neurological presentations, and to determine the cut‐off of the IgG index for the detection of these pathological IgG.

CSF results were retrieved from a database of 2902 samples using the keywords “SLE” or “lupus”. Only the first CSF sample taken before treatment for each neurological episode in each patient was analysed. Samples from traumatic subarachnoid haemorrhage were excluded. Cases were ascertained according to the American College of Rheumatology classification criteria.4 Neurological presentations were classified into neuropsychiatric SLE (NPSLE) according to the American College of Rheumatology criteria5 and other non‐NPSLE conditions. A total of 57 results from 54 patients were eligible for the analysis.

The 63 neurological presentations among the 57 neurological episodes were classified as inflammatory (n = 49) and non‐inflammatory (n = 13) according to the underlying pathogenesis determined by clinical features, MRI findings and response to immunosuppressive treatment. Table 11 shows the distribution of CSF OCBs, positive IgG index (>0.6) and the discrepancy between the two methods among these conditions. CSF OCBs were more frequently detected in inflammatory (26.5%) than in non‐inflammatory conditions, including focal NPSLE and non‐SLE‐related conditions (0%; p = 0.05), but not for positive IgG index (p = 1.0). The different rates of detection of CSF OCBs in NPSLE reflected heterogeneity in the underlying pathogenesis where microthrombi or vasculitis may cause damage to the blood–brain barrier.6,7,8 Although serum autoantibodies that cross react with antigens present in brain tissue have been shown to cause neuronal death through a damaged blood–brain barrier in the mouse model,9 our study suggested intrathecal synthesis of autoantibodies as another possible pathogenetic mechanism.

Table thumbnail
Table 1 Discrepancy in intrathecal IgG production according to qualitative and quantitative methods and the presence of serum hypo‐ and hypergammaglobulinaemia in patients with systemic lupus erythematosus with inflammatory and non‐inflammatory ...

There was agreement between IEF and IgG index on the presence (17.5%, n = 10) and absence (31.6%, n = 18) of intrathecal IgG synthesis, giving a discrepancy rate of 50.9% (29/56). This discrepancy was found to correlate with the presence of serum hypogammaglobulinaemia or hypergammaglobulinaemia (r = 0.86, p = 0.004), which was present in 23 (40.3%) samples. This suggested a non‐linear relationship between the IgG ratio and the albumin ratio in the formula for IgG in these ranges of IgG.10 IEF is thus superior to the IgG index for detection in patients with SLE.

CSF OCBs were found to correlate with the IgG index in inflammatory neurological conditions with higher sensitivity using a higher cut‐off of the IgG index ([gt-or-equal, slanted]0.81; fig 11).). The presence of CSF OCBs irrespective of the IgG index may suggest a specific immune response, whereas quantitatively increased IgG without OCBs might indicate a non‐specific polyclonal response. Studies on the specificities of CSF OCBs may provide clues to the underlying pathogenesis.

figure ar61069.f1
Figure 1 Detection rate of cerebrospinal fluid oligoclonal bands (OCBs) in different ranges of IgG index in inflammatory and non‐inflammatory neurological conditions in patients with systemic lupus erythemaosus. CNS, central nervous system; ...

In conclusion, our study showed that intrathecal production of IgG was found in inflammatory NPSLE. IEF is the preferred method of detection. Other investigation results should be considered for diagnosis because of its lack of discriminative power for NPSLE and CNS infections.


CSF - cerebrospinal fluid

IEF - isoelectric focusing

OCB - oligoclonal band

NPSLE - neuropsychiatric SLE

SLE - systemic lupus erythematosus


Competing interests: None.


1. West S G. Neuropsychiatric lupus. Rheum Dis Clin North Am 1994. 20129–158.158 [PubMed]
2. Link H, Tibbling G. Principles of albumin and IgG analysis in neurological disorders. The evaluation of IgG synthesis within CNS in multiple sclerosis. Scand J Clin Lab Invest 1977. 37385–401.401 [PubMed]
3. Correale J. Oligoclonal bands and antibody responses in multiple sclerosis. J Neurol 2002. 249375–389.389 [PubMed]
4. Tan E M, Cohen A S, Fries J F, Masi A T, McShane D J, Rothfield N F. et al The 1982 revised criteria for the classification of systemic lupus erythematosus. Arthritis Rheum 1982. 251271–1277.1277 [PubMed]
5. ACR Ad hoc Committee on Neuropsychiatric Lupus Nomenclature The American College of Rheumatology Nomenclature and case definitions for neuropsychiatric lupus syndromes. Arthritis Rheum 1999. 42599–608.608 [PubMed]
6. Kerr D A, Ayetey H. Immunopathogenesis of acute transverse myelitis. Curr Opin Neurol 2002. 15339–347.347 [PubMed]
7. Lampropoulos C E, Hughes G R. The antiphospholipid (Hughes') syndrome: changing the face of neurology. Eur J Intern Med 2004. 15147–150.150 [PubMed]
8. Abbott N J, Mendonca L L, Dolman D E. The blood‐brain barrier in systemic lupus erythematosus. Lupus 2003. 12908–915.915 [PubMed]
9. Kowal C, DeGiorgio L A, Nakaoka T, Hetherington H, Herta P T, Diamond B. et al Cognition and immunity; antibody impairs memory. Immunity 2004. 21179–188.188 [PubMed]
10. Mclean B N, Luxton R W, Thompson E J. A study of immunoglobulin G in the cerebrospinal fluid of 1007 patients with suspected neurological disease using isoelectric focusing and the log IgG‐index. Brain 1990. 1131269–1289.1289 [PubMed]

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