Systemic lupus erythematosus (SLE, OMIM 152700) is a complex autoimmune disease that affects 0.05% of the Western population, predominantly women. A number of susceptibility loci for SLE have been suggested in different populations, but the nature of the susceptibility genes and mutations is yet to be identified. We previously reported a susceptibility locus (SLEB2) for Nordic multi-case families. Within this locus, the programmed cell death 1 gene (PDCD1, also called PD-1) was considered the strongest candidate for association with the disease. Here, we analyzed 2,510 individuals, including members of five independent sets of families as well as unrelated individuals affected with SLE, for single-nucleotide polymorphisms (SNPs) that we identified in PDCD1. We show that one intronic SNP in PDCD1 is associated with development of SLE in Europeans (found in 12% of affected individuals versus 5% of controls; P = 0.00001, r.r. (relative risk) = 2.6) and Mexicans (found in 7% of affected individuals versus 2% of controls; P = 0.0009, r.r. = 3.5). The associated allele of this SNP alters a binding site for the runt-related transcription factor 1 (RUNX1, also called AML1) located in an intronic enhancer, suggesting a mechanism through which it can contribute to the development of SLE in humans.

Clinical and laboratory manifestations and outcome of systemic lupus erythematosus (SLE) may vary in different populations. A prospective multinational inception cohort should prove useful in identifying the influence of ethnicity on the clinical characteristics of SLE. We therefore analyzed clinical, laboratory, and prognostic variables in Latin American SLE patients with disease of recent onset who were entered into a prospective cohort, and compared these variables in the cohort's 3 major ethnic groups. Thirty-four centers from 9 Latin American countries participated by randomly incorporating SLE patients within 2 years of diagnosis into a standardized database. Participating centers were selected for their expertise in diagnosing and managing SLE. We were then able to evaluate prospectively socioeconomic variables, ethnicity, type of medical care, clinical and laboratory features, disease activity, damage, and mortality at each site. A coordinating center controlled the quality of the information submitted. Of the 1,214 SLE patients included in the cohort, 537 were mestizos, 507 were white, and 152 were African-Latin American (ALA). (There were also small numbers of pure Amerindian and oriental individuals.) Significant differences were found between them in socioeconomic characteristics, type of care, and level of education favoring whites. Mestizos and ALA were younger at onset. Delay to diagnosis and disease duration was shorter in ALA. Fever was more frequent in whites; discoid lesions in ALA; renal disease and lymphopenia in mestizos and ALA. Although we found differences in background variables between ethnic groups from different countries, mestizos from 2 distant countries (Argentina and Mexico) were clinically akin and showed similar differences to whites. Mortality was associated with lower education, poor medical coverage, and shorter follow-up. In an exploratory model nonwhite ethnicity was associated with renal disease and lymphopenia, damage, and cumulative American College of Rheumatology criteria. These differences in clinical, prognostic, socioeconomic, educational, and access to medical care features in Latin American lupus patients of 3 major ethnic groups from 9 different countries may have an impact on the patients' disease. "Hispanics," as they have come to be generically termed on the basis of language, actually constitute a markedly heterogeneous group of subjects.

SummaryInterleukin-10 (IL-10) is produced at a high level by B lymphocytes and monocytes of patients with systemic lupus erythematosus (SLE). In the present work, we analyzed whether this increased production of IL-10 contributed to the abnormal production of immunoglobulins (Ig) and of autoantibodies in SLE. The role of IL-10 was compared with that of IL-6, another cytokine suspected to play a role in these abnormalities. The spontaneous in vitro production of IgM, IgG, and IgA by peripheral blood mononuclear cells from SLE patients was weakly increased by recombinant IL (rlL)-6, but strongly by rlL-10. This production was not significantly affected by an anti-IL-6 mAb but was decreased by an anti-IL-10 mAb. We then tested the in vivo effect of these antibodies in severe combined immunodeficiency mice injected with PBMC from SLE patients. The anti-IL-6 mAb did not significantly affect the serum concentration of total human IgG and of anti-double-stranded DNA IgG in the mice. In contrast, the anti-IL-10 mAb strongly inhibited the production of autoantibodies, and, to a lesser extent, that of total human IgG. These results indicate that the Ig production by SLE B lymphocytes is largely IL-10 dependent, and that the increased production of IL-10 by SLE B lymphocytes and monocytes may represent a critical mechanism in the emergence of the autoimmune manifestations of the disease.

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Objective. To determine whether there is familial aggregation of systemic lupus erythematosus (SLE) and/or other autoimmune diseases in SLE patients and to identify clinical differences between patients with and those without familial autoimmunity.Methods. We interviewed members of the Grupo Latinoamericano de Estudio del Lupus Eritematoso (GLADEL) inception cohort of 1,214 SLE patients to ascertain whether they had relatives with SLE and/or other autoimmune diseases. Identified relatives were studied. Familial aggregation was tested using reported highest and intermediate population prevalence data for SLE, rheumatoid arthritis (RA), or all autoimmune diseases, and studies were performed to identify the genetic model applicable for SLE.Results. We identified 116 first-, second-, or thirddegree relatives with SLE, 79 with RA, 23 with autoimmune thyroiditis, 3 with scleroderma, 1 with polymyositis, and 16 with other autoimmune diseases, related to 166 of the 1,177 SLE patients in the GLADEL cohort who agreed to participate. Forty-two SLE patients had 2 or more relatives with an autoimmune disease. We found a sibling of 5.8 and 29.0 for SLE and of 3.2-5.3 for RA, when comparing with their reported high or intermediate population prevalence, respectively. We also found familial aggregation for autoimmune disease in general ( sibling ‫؍‬ 1.5) and determined that for SLE, a polygenic additive genetic model, rather than a multiplicative one, is applicable.Conclusion. In SLE there is familial aggregation of SLE, RA, and autoimmune disease in general. A polygenic additive model applies for SLE. American Indian-white Mestizo SLE patients and those with higher socioeconomic level were more likely to have familial autoimmunity.

The objective of the study was to evaluate the influence of the male gender in the clinical presentation and outcome of systemic lupus erythematosus in a prospective inception cohort of Latin-American patients. Of the 1214 SLE patients included in the GLADEL cohort, 123 were male. Demographic characteristics as well as clinical manifestations, laboratory profile, activity and damage scores were evaluated at onset and during the course of the disease and compared with female patients. The median age at onset of the male patients was 27 and that at diagnosis 29.2 years. Delay to diagnosis was shorter in males (134 versus 185 days, P = 0.01). At onset, men more frequently showed fever (42.3 versus 27.0%, P = 0.001) and weight loss (23.6 versus 11.8%, P = 0.001). During disease course the incident of symptoms was: fever, 67.8 versus 55.6%, P = 0.012; weight loss, 47.2 versus 24.3%, P = 0.001; arterial hypertension, 37.4 versus 25.8%, P = 0.007; renal disease (persistent proteinuria and/or cellular casts), 58.5 versus 44.6%, P = 0.004); and hemolytic anemia, 19.5 versus 10.9%, P = 0.008. The laboratory results showed that: men more frequently had IgG anticardiolipin antibodies (68.2 versus 49%, P = 0.02) and low C3 (61.3 versus 48.1%, P = 0.03); 5/123 men died (4%) compared with 29/1091 women (2.7%). In conclusion, 10% of GLADEL's cohort patients were male. They showed a distinctive profile with shorter delay to diagnosis, higher incidence of fever, weight loss, arterial hypertension, renal disease, hemolytic anemia, IgG anticardiolipin antibodies and low C3. Although not statistically significant, mortality was higher in men.

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This is the first report of IL-10 antagonist administration to humans. The study shows the involvement of IL-10 in the pathogenesis of SLE, and indicates that the use of IL-10 antagonists may be beneficial in the management of refractory SLE.