CD73-generated adenosine restricts lymphocyte migration into draining lymph nodes.

After an inflammatory stimulus, lymphocyte migration into draining lymph nodes increases dramatically to facilitate the encounter of naive T cells with Ag-loaded dendritic cells. In this study, we show that CD73 (ecto-5\u27-nucleotidase) plays an important role in regulating this process. CD73 produces adenosine from AMP and is expressed on high endothelial venules (HEV) and subsets of lymphocytes. Cd73(-/-) mice have normal sized lymphoid organs in the steady state, but approximately 1.5-fold larger draining lymph nodes and 2.5-fold increased rates of L-selectin-dependent lymphocyte migration from the blood through HEV compared with wild-type mice 24 h after LPS administration. Migration rates of cd73(+/+) and cd73(-/-) lymphocytes into lymph nodes of wild-type mice are equal, suggesting that it is CD73 on HEV that regulates lymphocyte migration into draining lymph nodes. The A(2B) receptor is a likely target of CD73-generated adenosine, because it is the only adenosine receptor expressed on the HEV-like cell line KOP2.16 and it is up-regulated by TNF-alpha. Furthermore, increased lymphocyte migration into draining lymph nodes of cd73(-/-) mice is largely normalized by pretreatment with the selective A(2B) receptor agonist BAY 60-6583. Adenosine receptor signaling to restrict lymphocyte migration across HEV may be an important mechanism to control the magnitude of an inflammatory response

High Affinity Antibodies against Influenza Characterize the Plasmablast Response in SLE Patients After Vaccination

We thank Elena Solomaha for advice on SPR experiments, Angela Hayes for clerical support, Christina Helms and Lori Garman for technical assistance, Gillian M. Air for providing influenza viruses; Linda F. Thompson for early involvement in the study and Meghan Sullivan, Irvin Ho and Sarah F. Andrews for helpful comments on the manuscript.Breakdown of B cell tolerance is a cardinal feature of systemic lupus erythematosus (SLE). Increased numbers of autoreactive mature naïve B cells have been described in SLE patients and autoantibodies have been shown to arise from autoreactive and non-autoreactive precursors. How these defects, in the regulation of B cell tolerance and selection, influence germinal center (GC) reactions that are directed towards foreign antigens has yet to be investigated. Here, we examined the characteristics of post-GC foreign antigen-specific B cells from SLE patients and healthy controls by analyzing monoclonal antibodies generated from plasmablasts induced specifically by influenza vaccination. We report that many of the SLE patients had anti-influenza antibodies with higher binding affinity and neutralization capacity than those from controls. Although overall frequencies of autoreactivity in the influenza-specific plasmablasts were similar for SLE patients and controls, the variable gene repertoire of influenza-specific plasmablasts from SLE patients was altered, with increased usage of JH6 and long heavy chain CDR3 segments. We found that high affinity anti-influenza antibodies generally characterize the plasmablast responses of SLE patients with low levels of autoreactivity; however, certain exceptions were noted. The high-avidity antibody responses in SLE patients may also be correlated with cytokines that are abnormally expressed in lupus. These findings provide insights into the effects of dysregulated immunity on the quality of antibody responses following influenza vaccination and further our understanding of the underlying abnormalities of lupus.Yeshttp://www.plosone.org/static/editorial#pee

The TCR ligand-inducible expression of CD73 marks γδ lineage commitment and a metastable intermediate in effector specification

Numerous studies indicate that γδ T cell receptor (γδTCR) expression alone does not reliably mark commitment of early thymic progenitors to the γδ fate. This raises the possibility that the γδTCR is unable to intrinsically specify fate and instead requires additional environmental factors, including TCR–ligand engagement. We use single cell progenitor assays to reveal that ligand acts instructionally to direct adoption of the γδ fate. Moreover, we identify CD73 as a TCR ligand-induced cell surface protein that distinguishes γδTCR-expressing CD4(−)CD8(−) progenitors that have committed to the γδ fate from those that have not yet done so. Indeed, unlike CD73(−) γδTCR(+) progenitors, which largely adopt the αβ fate upon separation from the intrathymic selecting environment, those that express CD73 remain CD4(−)CD8(−) and committed to the γδ fate. CD73 is expressed by >90% of peripheral γδ cells, suggesting this is a common occurrence during development. Moreover, CD73 induction appears to mark a metastable intermediate stage before acquisition of effector function, suggesting that γδ lineage and effector fate are specified sequentially. These findings have important implications for the role of ligand in γδ lineage commitment and its relationship to the specification of effector fate

High Affinity Antibodies against Influenza Characterize the Plasmablast Response in SLE Patients After Vaccination

Breakdown of B cell tolerance is a cardinal feature of systemic lupus erythematosus (SLE). Increased numbers of autoreactive mature naïve B cells have been described in SLE patients and autoantibodies have been shown to arise from autoreactive and non-autoreactive precursors. How these defects, in the regulation of B cell tolerance and selection, influence germinal center (GC) reactions that are directed towards foreign antigens has yet to be investigated. Here, we examined the characteristics of post-GC foreign antigen-specific B cells from SLE patients and healthy controls by analyzing monoclonal antibodies generated from plasmablasts induced specifically by influenza vaccination. We report that many of the SLE patients had anti-influenza antibodies with higher binding affinity and neutralization capacity than those from controls. Although overall frequencies of autoreactivity in the influenza-specific plasmablasts were similar for SLE patients and controls, the variable gene repertoire of influenza-specific plasmablasts from SLE patients was altered, with increased usage of JH6 and long heavy chain CDR3 segments. We found that high affinity anti-influenza antibodies generally characterize the plasmablast responses of SLE patients with low levels of autoreactivity; however, certain exceptions were noted. The high-avidity antibody responses in SLE patients may also be correlated with cytokines that are abnormally expressed in lupus. These findings provide insights into the effects of dysregulated immunity on the quality of antibody responses following influenza vaccination and further our understanding of the underlying abnormalities of lupus