There is growing interest in the development of protein switches, which are proteins whose function, such as binding a target molecule, can be modulated through environmental triggers. Efforts to engineer highly pH sensitive protein-protein interactions typically rely on the rational introduction of ionizable groups in the protein interface. Such experiments are typically time intensive and often sacrifice the protein's affinity at the permissive pH. The underlying thermodynamics of proton-linkage dictate that the presence of multiple ionizable groups, which undergo a pK a change on protein binding, are necessary to result in highly pH-dependent binding. To test this hypothesis, a novel combinatorial histidine library was developed where every possible combination of histidine and wild-type residue is sampled throughout the interface of a model anti-RNase A single domain VHH antibody. Antibodies were coselected for high-affinity binding and pH-sensitivity using an in vitro, dual-function selection strategy. The resulting antibodies retained near wild-type affinity yet became highly sensitive to small decreases in pH, drastically decreasing their binding affinity, due to the incorporation of multiple histidine groups. Several trends were observed, such as histidine ''hot-spots,'' which will help enhance the development of pH switch proteins as well as increase our understanding of the role of ionizable residues in protein interfaces. Overall, the combinatorial approach is rapid, general, and robust and should be capable of producing highly pH-sensitive protein affinity reagents for a number of different applications.

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The importance of CD4 T cells in tumour immunity has been increasingly recognised, with recent reports describing robust CD4 T cell-dependent tumour control in mice whose immune-regulatory mechanisms have been disturbed by irradiation, chemotherapy, immunomodulatory therapy and/or constitutive immunodeficiency. Tumour control in such models has been attributed in large part to direct Major Histocompatibility Complex (MHC) class II-dependent CD4 T cell killing of tumour cells. To test whether CD4 T cells can eradicate tumours without directly killing tumour cells, we developed an animal model in which tumour-derived antigen could be presented to T-cell receptor (TCR)-transgenic CD4 T cells by host but not tumour MHC class II molecules. In I-E(+) mice bearing I-E(null) tumours, naive I-E-restricted CD4 T cells proliferated locally in tumour-draining lymph nodes after recognising tumour-derived antigen on migratory dendritic cells. In lymphopaenic but not immunosufficient hosts, CD4 T cells differentiated into polarised T helper type 1 (Th1) cells expressing interferon gamma (IFNγ), tumor necrosis factor alpha (TNFα) and interleukin (IL)-2 but little IL-17, and cleared established tumours. Tumour clearance was enhanced by higher TCR affinity for tumour antigen-MHC class II and was critically dependent on IFNγ, as demonstrated by early tumour escape in animals treated with an IFNγ blocking antibody. Thus, CD4 T cells and IFNγ can control tumour growth without direct T-cell killing of tumour cells, and without requiring additional adaptive immune cells such as CD8 T cells and B cells. Our results support a role for effective CD4 T cell-dependent tumour immunity against MHC class II-negative tumours.

The primary immune role of B cells is to produce antibodies, but they can also influence T cell function via antigen presentation and, in some contexts, immune regulation. Whether their roles in tumour immunity are similar to those in other chronic immune responses such as autoimmunity and chronic infection, where both pro- and anti-inflammatory roles have been described, remains controversial. Many studies have aimed to define the role of B cells in antitumor immune responses, but despite this considerable body of work, it is not yet possible to predict how they will affect immunity to any given tumour. In many human cancers, the presence of tumour-infiltrating B cells and tumour-reactive antibodies correlates with extended patient survival, and this clinical observation is supported by data from some animal models. On the other hand, T cell responses can be adversely affected by B cell production of immunoregulatory cytokines, a phenomenon that has been demonstrated in humans and in animal models. The isotype and concentration of tumour-reactive antibodies may also influence tumour progression. Recruitment of B cells into tumours may directly reflect the subtype and strength of the anti-tumour T cell response. As the response becomes chronic, B cells may attenuate T cell responses in an attempt to decrease host damage, similar to their described role in chronic infection and autoimmunity. Understanding how B cell responses in cancer are related to the effectiveness of the overall anti-tumour response is likely to aid in the development of new therapeutic interventions against cancer.

Abstract. In man the Sdaantigen is present in most secretions with the greatest concentration in urine. There is little difference in the amount of Sdasubstance in the urine of newborn infants, pregnant women and normal adults but there is a much greater amount in the saliva of newborn infants than in adults. Approximately half the people whose red cells group as Sd(a‐) secrete Sdasubstance in the urine. Anti‐Sdaantibody is present in 50% of Sd(a‐) non‐secretors of Sdasubstance, though most of these antibodies only react with the strongest Sd(a +) cells. The greatest Sdaactivity has been found in human meconium, guinea pig urine and guinea pig kidney. Activity can be detected in the urine of many animal species. The kidneys of 5 bird species did not contain Sda.

Background Chronic inflammation is the driver of liver injury and results in progressive fibrosis and eventual cirrhosis with consequences including both liver failure and liver cancer. We have previously described increased expression of the highly multifunctional glycoprotein CD147 in liver injury. This work describes a novel role of CD147 in liver inflammation and the importance of leukocyte aggregates in determining the extent of liver injury. Methods Non-diseased, progressive injury, and cirrhotic liver from humans and mice were examined using a mAb targeting CD147. Inflammatory cell subsets were assessed by multiparameter flow cytometry. Results In liver injury, we observe abundant, intrahepatic leukocyte clusters defined as ≥5 adjacent CD45 + cells which we have termed “leukocyte aggregates”. We have shown that these leukocyte aggregates have a significant effect in determining the extent of liver injury. If CD147 is blocked in vivo , these leukocyte aggregates diminish in size and number, together with a marked significant reduction in liver injury including fibrosis. This is accompanied by no change in overall intrahepatic leukocyte numbers. Further, blocking of aggregation formation occurs prior to an appreciable increase in inflammatory markers or fibrosis. Additionally, there were no observed, “off-target” or unpredicted effects in targeting CD147. Conclusion CD147 mediates leukocyte aggregation which is associated with the development of liver injury. This is not a secondary effect, but a cause of injury as aggregate formation proceeds other markers of injury. Leukocyte aggregation has been previously described in inflammation dating back over many decades. Here we demonstrate that leukocyte aggregates determine the extent of liver injury.

The role of B cells and antibodies in anti-tumor immunity is controversial, with both positive and negative effects reported in animal models and clinical studies. We developed a murine B16.F10 melanoma model to study the effects of collaboration between tumor-specific CD4+ T cells and B cells on tumor control. By incorporating T cell receptor transgenic T cells and B cell receptor isotype switching B cells, we were able to track the responses of tumor-reactive T and B cells and the development of anti-tumor antibodies in vivo. In the presence of tumor-specific B cells, the number of tumor-reactive CD4+ T cells was reduced in lymphoid tissues and the tumor itself, and this correlated with poor tumor control. B cells had little effect on the Th1 bias of the CD4+ T cell response, and the number of induced FoxP3+ regulatory cells (iTregs) generated from within the original naive CD4+ T cell inoculum was unrelated to the degree of B cell expansion. In response to CD4+ T cell help, B cells produced a range of isotype-switched anti-tumor antibodies, principally IgG1, IgG2a/c and IgG2b. In the absence of CD4+ T cells, B cells responded to agonistic anti-CD40 administration by switching to production of IgG2a/c and, to a lesser extent, IgG1, IgG3, IgA and IgE, which reduced the number of lung metastases after i.v. tumor inoculation but had no effect on the growth of subcutaneous tumors.

Several recent studies have shown that both lower doses and shorter durations of systemic corticosteroids have similar efficacy for treatment of acute exacerbation of chronic obstructive pulmonary disease (AECOPD). However, each trial has limitations that constrain direct applicability to a US hospital population. The aim of this study was to determine whether, in a US community hospital, low doses of corticosteroids provide the lowest risk of adverse effects without increasing length of stay or readmission rate. A single-center retrospective cohort was performed using patients meeting criteria for AECOPD. Primary endpoints included length of hospitalization, proportion of patients with >30% increase in blood glucose from baseline, and rate of 30-day readmission; multivariable regression analysis was used for comparison. The 3 inpatient cumulative dose range groups were low: ≤250-mg prednisone equivalents, medium: 251 to 500 mg, and high: ≥501 mg. A total of 665 records were evaluated, with 369 records included. As the corticosteroid dose ranges increased, there were more patients with increased blood glucose (33.3%, 54.4%, 59.9%). When holding all other factors constant, there was a statistically significant increase in patients with elevated blood glucose with the medium- and high-dose groups as compared with the low-dose group ( < .009, < .001), the average length of stay was 21.3 hours higher in the high-dose group as compared with the low-dose group ( < .001), and there were no significant differences in readmission rates between the dose groups. The lowest dose range of corticosteroids was associated with the lowest rate of impaired blood glucose without a statistically significant increase in length of stay or readmission rate.