In lupus autoimmunity, pathogenic IgG autoantibodies that fix complement and bind FcGammaR on inflammatory cells, are produced with help from T helper (Th1 and Th17) cells specific for peptides from nucleosomes of apoptotic cells; and these Th cells also infiltrate vital organs (1-9). Macrophages (e.g. tingible body MΦ), and DCs are normally tolerant to apoptotic cell antigens (10), but they are activated to present such autoantigens after binding to IgG immune complexes (IC) containing apoptotic cell derived DNA/RNA, which then dually stimulate their TLR and FcGammaR (11-16). Hence, to generate the activating IC, IgG-switched autoantibodies have to be made first by T cell help. Moreover, B cells become efficient antigen presenting cells (APC) to Th cells pre-primed by other APC (17), or if the B cells have developed high affinity somatically mutated receptors by T cell help (18). Thus, conventional APCs participate as disease progresses, but it is unknown who initially primes autoimmune Th cells. We fractionated spleen cells of lupus prone SNF1 mice in search of such APC. To produce lupus-prone SNF1 mice, NZB and SWR mice were purchased from The Jackson Laboratory, ME to breed the lupus-prone SNF1 hybrids (19). Female SNF1 mice, like BWF1, have high serum levels of IgG class anti-DNA and other anti-nuclear autoantibodies b...
...each type of APC population. Total RNA was purified from each APC after incubation with nucleosomes (20µg/ml) for 6h. RNA expression analysis of each type of APC isolate in triplicate was performed at our Genomics Core Facility using Illumina Mouse WG-6 v2.0 Expression Beadchips, which provides coverage of around 45,281 genes and expressed sequence tags. Raw signal intensities of each probe were obtained using data analysis software (Beadstudio; Illumina) and imported to the Lumi package of Bioconductor for data analysis. Before transformation and normalization (24-26), A/P call detection was performed based on detection p value. 20,890 out of 45,281 probes with less than 0.01 were considered as valid signals. For each pairs of four comparisons: Lin–c-Kit+CX3CR1– versus Lin–c-Kit+ CX3CR1+; Lin–c-Kit+pure vs. Lin–c-Kit+CX3CR1+; Lin–c-Kit+CX3CR1– vs. DC; and Lin–c-Kit+pure vs. DC; differentially expressed genes were identified using an Analysis of Variance (ANOVA) model with empirical Bayesian variance estimation (27). Thus, 1,619 genes were identified as being differentially expressed (up or down) on the basis of a statistically significant (raw P-value < 0.01 and false discovery rate adjusted P-value < 0.05), and 1.5-fold change (up or down) in expression level in at least one of the comparisons, and out of these 230 genes were significantly UP-regulated by the above criteria in all 4 pair comparisons.
ORGANISM(S): Mus musculus
