ObjectiveSystemic lupus is a chronic autoimmune disease characterised by its phenotypic heterogeneity. Neutropaenia is a frequent event in SLE occurring in 20%–40% of patients depending on the threshold value of neutrophil count. On a daily basis, the management of neutropaenia in SLE is difficult with several possible causes. Moreover, the infectious consequences of neutropaenia in SLE remain not well defined.Methods998 patients from the Lupus BioBank of the upper Rhein (LBBR), a large German and French cohort of patients with SLE, mostly of Caucasian origin (83%), were included in this study. Neutropaenia was considered when neutrophil count was below 1800×106/L. An additional analysis of detailed medical records was done for 65 LBBR patients with neutropaenia.Results208 patients with neutropaenia (21%) were compared with 779 SLE patients without neutropaenia. Neutropaenia in SLE was significantly associated with thrombocytopaenia (OR 4.11 (2.57–10.3)), lymphopaenia (OR 4.41 (2.51–11.5)) and low C3 (OR 1.91 (1.03–4.37)) in multivariate analysis. 65 representative patients with neutropaenia were analysed. Neutropaenia was moderate to severe in 38%, chronic in 31%, and both severe and chronic in 23% of cases. Moderate to severe and chronic neutropaenia were both associated with lymphopaenia and thrombopaenia. Chronic neutropaenia was also associated anti-Ro/SSA antibodies and moderate to severe neutropaenia with oral ulcers.ConclusionThis study is to date the largest cohort to describe neutropaenia in SLE. Neutropaenia displays a strong association with other cytopaenias, suggesting a common mechanism. Chronic neutropaenia is associated with anti-Ro/SSA antibodies with or without identified Sjögren’s disease.

SUMMARYTbe allotypic forms ofthe C3b/C4b receptor (CRl, CD35) differ in length, in the number of expressed C3b binding sites and thus in their ability to mediate the processing of circulating C3-and C4-bearing immune complexes. We have used a combination of three informative restriction fragment length polymorphisms (RFLPs) to assess the frequencies of the F (most frequent allele comprised of four long homologous repeats (LHR)), S (five LHR) and F' (three LHR) alleles ofthe C3b/C4b receptor (CRl, CD35) in a French population of patients with systemic lupus erythematosus (SLE) (« = 63) and healthy controls {n= 158). A significantly higher frequency of tbe S phenotype was observed among patients (51 %) as compared with controls (26%). The F' allele was found in 2/61 patients and 1/85 healthy controls, indicating the rare occurrence ofthe short CRl allele in SLE. This allele is also extremely rare in the normal population. The overrepresentation ofthe S long allele among patients is indicative of a genetic linkage between CRl and susceptibility to SLE.

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