Autoantibody-Positive Healthy Individuals Display Unique Immune Profiles That May Regulate Autoimmunity.

OBJECTIVE: Antinuclear antibodies (ANAs) are detected in ∼18% of females, yet autoimmune disease develops in only 5-8%. Immunologic differences between ANA-positive healthy individuals and patients with systemic lupus erythematosus (SLE) may elucidate the regulatory mechanisms by which ANA-positive individuals avoid transition to clinical autoimmune disease. METHODS: Healthy individuals (n = 790) were screened for autoantibodies specific for 11 antigens associated with lupus, systemic sclerosis, and Sjögren's syndrome. From this screening, 31 European American ANA-positive healthy individuals were selected and demographically matched to ANA-negative controls and SLE patients. Serum cytokine profiles, leukocyte subset frequency, and reactivity were analyzed by multiplex assays, immunophenotyping, and phosphospecific flow cytometry. RESULTS: Of 790 individuals screened, 57 (7%) were ANA-positive. The majority of proinflammatory cytokines, including interferon-γ (IFNγ), tumor necrosis factor, interleukin-17 (IL-17), and granulocyte colony-stimulating factor, exhibited a stepwise increase in serum levels from ANA-negative controls to ANA-positive healthy individuals to SLE patients (P < 0.0001). IFNα, IFNß, IL-12p40, and stem cell factor/c-Kit ligand were increased in SLE patients only (P < 0.05). B lymphocyte stimulator (BlyS) was elevated in SLE patients but decreased in ANA-positive individuals (P < 0.001). Further, IL-1 receptor antagonist (IL-1Ra) was down-regulated in SLE patients only (P < 0.0001). ANA-positive individuals had increased frequencies of monocytes, memory B cells, and plasmablasts and increased levels of pSTAT-1 and pSTAT-3 following IFNα stimulation compared with ANA-negative controls (P < 0.05). CONCLUSION: ANA-positive healthy individuals exhibit dysregulation in multiple immune pathways yet differ from SLE patients by the absence of elevated IFNs, BLyS, IL-12p40, and stem cell factor/c-Kit ligand. Further, severely decreased levels of IL-1Ra in SLE patients compared with ANA-positive individuals may contribute to disease development. These results highlight the importance of IFN-related pathways and regulatory elements in SLE pathogenesis.

Vitamin d deficiency in a multiethnic healthy control cohort and altered immune response in vitamin D deficient European-American healthy controls.

OBJECTIVE: In recent years, vitamin D has been shown to possess a wide range of immunomodulatory effects. Although there is extensive amount of research on vitamin D, we lack a comprehensive understanding of the prevalence of vitamin D deficiency or the mechanism by which vitamin D regulates the human immune system. This study examined the prevalence and correlates of vitamin D deficiency and the relationship between vitamin D and the immune system in healthy individuals. METHODS: Healthy individuals (n = 774) comprised of European-Americans (EA, n = 470), African-Americans (AA, n = 125), and Native Americans (NA, n = 179) were screened for 25-hydroxyvitamin D [25(OH)D] levels by ELISA. To identify the most noticeable effects of vitamin D on the immune system, 20 EA individuals with severely deficient (<11.3 ng/mL) and sufficient (>24.8 ng/mL) vitamin D levels were matched and selected for further analysis. Serum cytokine level measurement, immune cell phenotyping, and phosphoflow cytometry were performed. RESULTS: Vitamin D sufficiency was observed in 37.5% of the study cohort. By multivariate analysis, AA, NA, and females with a high body mass index (BMI, >30) demonstrate higher rates of vitamin D deficiency (p<0.05). Individuals with vitamin D deficiency had significantly higher levels of serum GM-CSF (p = 0.04), decreased circulating activated CD4+ (p = 0.04) and CD8+ T (p = 0.04) cell frequencies than individuals with sufficient vitamin D levels. CONCLUSION: A large portion of healthy individuals have vitamin D deficiency. These individuals have altered T and B cell responses, indicating that the absence of sufficient vitamin D levels could result in undesirable cellular and molecular alterations ultimately contributing to immune dysregulation.

New technologies for autoimmune disease monitoring.

PURPOSE OF REVIEW: This article will review new technologies used to characterize the immune phenotype of cells and serum for potential use in studies of autoimmunity. RECENT FINDINGS: One area of recent development in studies of immune phenotyping is the contrast between cells of the immune system at rest and following activation. This simply involves comparing these cells at rest and following ligand-induced activation and measuring signaling system activation (phosphoepitope identification) or intracellular cytokine production or activation-induced gene expression. Preliminary data using these techniques have begun to identify signatures of disease (biomarkers) that are only seen when using these activation-induced assays. One of the most exciting new technologies, cytometry by time-of-flight mass spectrometry, couples a flow cytometer to a mass spectrometer, allowing many more parameters to be analyzed per cell, and without spillover between assay reagents, compared to conventional optical flow cytometry (heavy ions, mass, replaces fluorophore readout). Another new technology to analyze soluble proteins, bead-based immunoassays, can simultaneously measure up to 75 soluble analytes in a multiplexed array. Other technologies provide similar innovations in terms of analytical content, throughput, and miniaturization. SUMMARY: We believe that new cellular genomic and protein-based technologies can provide key insights into autoimmune disease pathogenesis, progression, and therapy, and that these assays need to be applied in a systematic way to samples from patients with autoimmune diseases.