Project description:In order to assess the miRNA signature of B cells undergoing the germinal center reaction, we isolated three subsets of B cells from tonsils--naive (N), germinal center (GC), and memory (M) and looked at their miRNA profile. We looked at three subsets of B cells, isolated from tonsils obtained from four different donors. Thus, we profiled a total of 12 samples, and each tonsillar subset--N, GC, and M, had four biological replicates.
Project description:BFL-1 is an understudied anti-apoptotic protein that is upregulated in melanoma, certain forms of leukemias and lymphomas, and Epstein-Barr virus (EBV)-immortalized lymphoblastoid cell lines (LCLs). We have previously shown that BFL-1 is upregulated in LCLs through a viral-mediated chromatin conformation. However, BFL-1 is also highly expressed in uninfected B cells undergoing maturation in the germinal center. We therefore sought to determine the non-viral mechanisms underlying BFL-1 upregulation in B cells. Here, we characterized the chromatin landscape of maturing B cell subsets found in human tonsillar lymphoid tissue. While chromatin accessibility at the BFL-1 locus increases as naïve B cells enter the germinal center reaction, we found that BFL-1 expression during the transition from dark zone to light zone correlates with a significant increase in three-dimensional chromatin association between upstream enhancer regions and the BFL-1 transcriptional start site (TSS). Interestingly, both LCLs and germinal center light zone B cells shared similar chromatin architectures at the BFL-1 TSS, suggesting a conserved mechanism underlying BFL-1 upregulation. Increased BFL-1 in LCLs also protects against FasL and TRAIL-activated extrinsic apoptosis. In addition to BFL-1 expression, LCLs and germinal center light zone B cells share similar patterns of gene expression, suggesting strong evidence that EBV infection phenocopies various aspects of the germinal center reaction. From this, we infer that EBV-infected B cells co-opts strategies from germinal center light zone B cells to upregulate BFL-1 and enhance their survival in establishing long-lived latent infection.
Project description:We used an IL4-capture assay followed by FACS sorting, to isolate IL4-secreting TFH cells from a human tonsil and compared their transcriptomic profiles with CXCR5hi PD1hi IL4-negative tonsillar TFH cells and IL4-producing CXCR5neg non-TFH cells (TH2 cells). Our studies validate the notion of functionally distinct TFH subsets and identify genes that are specifically expressed in and define the human IL-4 secreting TFH cell subset.
Project description:In response to antigen challenge, human B cells clonally expand, undergo selection and differentiate within secondary lymphoid tissues to produce mature B cell subsets and high affinity antibodies necessary for an effective immune response. However, the interplay between affinity, antibody class and different B cell fates has proved challenging to decipher in primary human tissue. We have applied an integrated analysis of bulk and single-cell antibody repertoires paired with single-cell transcriptomics of human B cells from a model secondary lymphoid tissue. Specifically, here we have performed bulk B cell repertoire sequencing of the immunoglobulin heavy chain (IgH) for sorted B cell subsets from paediatric tonsil tissue. Matched single-cell gene expression and single-cell VDJ data are also available for the same patient donors.