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Immunocompetence may be affected by T-cell and antibody developments during fetal and neonatal life, by placental feeding, and by breast-feeding during infancy. Oral tolerance, introduced early in life, plays an important role in immunocompetence, but the actual mechanisms involved in developing oral tolerance require further study. Breast-feeding appears to be crucial in preventing many types of infections and possibly even autoimmune diseases.

Summary: Natural killer (NK) cells participate in the regulation of the immune response. However, the immunomodulatory function of NK cells in systemic lupus erythematosus (SLE) is not well understood. The aim of this study was to evaluate the regulatory function of NK cells in SLE patients and to identify the NK cells involved in the pathogenesis of this complex disease. We analysed the expression of NK receptors and co‐stimulatory molecules in peripheral NK cells (CD3–CD56+) from SLE patients, as well as the numbers of human leucocyte antigen D‐related (HLA‐DR)/CD11c+ NK cells. In addition, NK cell regulatory function was assessed by the detection of NK cell‐mediated dendritic cell (DC) lysis. We found that SLE patients showed increased numbers of immunoglobulin‐like transcript 2 (ILT2)+, CD86+ and CD134+ NK cells. Furthermore, NK cells from SLE patients induced higher levels of DC lysis. We were able to identify a new subset of NK cells co‐expressing CD11c and HLA‐DR. These atypical NK cells were increased in SLE patients when compared with controls. We have identified an expanded new subset of NK cells in SLE patients. This is the first study, to our knowledge, which demonstrates that NK cells in SLE patients have an altered phenotype with a high expression of receptors characteristic of dendritic cells. Our results suggest that the impairment in the regulatory function of NK cells, together with the increased number of DC‐like NK cells, could play an important role in the development of SLE and highlight the importance of NK cells as a future therapeutic target. [ABSTRACT FROM AUTHOR]

This study aimed to address whether bloodstream infections are a risk factor for the development of severe lupus flares, as well as clinical, immunological and microbiological features of patients with bloodstream infections that develop severe lupus flares. Methods: We performed a retrospective cohort study comparing 87 systemic lupus erythematosus (SLE) patients with bloodstream infections and 87 hospitalized SLE patients without bloodstream infections as a comparison group. All patients were followed up for at least 3 months or until one of the primary outcomes was developed (severe SLE flare according to SELENA/ SLEDAI score or death). Microbiological features of all bloodstream infections were recorded. The disease status at the end of follow up was registered. Results: A total of 23 patients (13.2%) developed a severe flare during follow up; among them, 20 (87%) had an associated episode of bloodstream infection (p<0.001). The most frequent flares were renal (43.4%) and severe thrombocytopenia (26%). After multivariate analysis, baseline-independent factors associated with severe SLE flare were bloodstream infection [hazard ratio (HR) 7.3, 95% confidence interval (CI) 2.13-24.95; p=0.002]. Among patients with bloodstream infections, low C4 levels (HR 2.43, 95% CI 1.04-5.69: p=0.04) and Streptococcus pneumoniae were associated with severe SLE flare (HR 3.41, 95% CI 1.68-6.91; p=0.012). Conclusions: SLE patients with bloodstream infections, especially due to S. pneumoniae, and low C4 levels, are at higher risk for development of severe SLE flares. [ABSTRACT FROM AUTHOR]