Activation of naive CD8 + T cells with antigen in the absence of skewing cytokines triggers their differentiation into effector CTL, which induces death of target cells. We show that CD8 + T cells activated in the presence of the cytokines IL-6 or IL-21 plus TGF-b similar to CD4 + T cells, develop into IL-17-producing (Tc17) cells. These cells display greatly suppressed cytotoxic function along with low levels of the CTL markers: T-box transcription factor Eomesodermin, granzyme B and IFN-c. Instead, these cells express hallmark molecules of Th17 program including retinoic acid receptor-related orphan receptor (ROR)ct, RORa, IL-21 and IL-23R. The expression of the type 17 master regulator RORct is causally linked to Tc17 generation, because its overexpression stimulates production of IL-17 in the presence of IL-6 or IL-21. Both, upregulation of the type 17 program as well as suppression of CTL differentiation are STAT3 dependent. Furthermore, Tc17 cells producing IL-17 but not granzyme B are also detectable in EAE, a mouse model for multiple sclerosis. Our data point to the existence of mutually exclusive CTL and Tc17 developmental pathways in vitro and in vivo.Key words: CTL . EAE . RORgt . STAT3 . Tc17Supporting Information available online Introduction CTL are important effector cells in the immune response to intracellular pathogens and tumors. They differentiate from naive CD8 + T cells following activation by antigen in the absence of skewing cytokines, and during this process they acquire the ability to destroy their targets by releasing cytotoxic molecules such as perforin and granzymes, from granules into the immunological synapse. In addition, CTL secrete cytokines, mostly IFN-g and TNF-a, which function to induce or augment inflammation [1][2][3].Two T-box transcription factors, Eomesodermin (Eomes) and T-bet, are important for the development of effector and memory CTL [4][5][6]. Studies using deletion, overexpression or dominant negative analogs of these factors have suggested that both of them are involved in the regulation of expression of granzyme B and perforin [4,5,7]. Consistent with these data, CD8 + T cells with combined deletion of the Eomes and Tbx21 (encoding T-bet) genes differentiate into cells with highly impaired cytotoxic activity and IFN-g production [8]. Instead, these cells produce Th17 type cytokines and express the IL-23 receptor (IL-23R) as well as the transcription factor retinoic acid receptor-related orphan receptor (ROR)gt, both of 1716Frontline which are characteristic for the type 17 differentiation program [8]. Thus, the phenotype of CD8 + T cells deficient for both Eomes and T-bet is reminiscent of the newly described Th17-cell subset.Th17 cells produce IL-17A, IL-17F, IL-21 and IL-22, which are highly pro-inflammatory and induce severe autoimmunity, e.g. during EAE, the mouse model for multiple sclerosis [9]. The differentiation of these cells requires TGF-b in combination with 11]. Two additional cytokines, IL-21 and IL-23, are also critically involved in the diffe...

Superagonistic CD28-specific monoclonal antibodies (CD28SA) are highly effective activators of regulatory T-cells (Treg cells) in rats, but a first-in-man trial of the human CD28SA TGN1412 resulted in an unexpected cytokine release syndrome. Using a novel mouse anti-mouse CD28SA, we re-investigate the relationship between Treg activation and systemic cytokine release. Treg activation by CD28SA was highly efficient but depended on paracrine IL-2 from CD28SA-stimulated conventional T-cells. Systemic cytokine levels were innocuous, but depletion of Treg cells prior to CD28SA stimulation led to systemic release of proinflammatory cytokines, indicating that in rodents, Treg cells effectively suppress the inflammatory response. Since the human volunteers of the TGN1412 study were not protected by this mechanism, we also tested whether corticosteroid prophylaxis would be compatible with CD28SA induced Treg activation. We show that neither the expansion nor the functional activation of Treg cells is affected by high-dose dexamethasone sufficient to control systemic cytokine release. Our findings warn that preclinical testing of activating biologicals in rodents may miss cytokine release syndromes due to the rapid and efficacious response of the rodent Treg compartment, and suggest that polyclonal Treg activation is feasible in the presence of antiphlogistic corticosteroid prophylaxis.

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Jumping spiders (Phidippus regius) are known for their ability to traverse various terrains and have targeted jumps within the fraction of a second to catch flying preys. Different from humans and insects, spiders use muscles to flex their legs, and hydraulic actuation for extension. By pressurizing their inner body fluid, they can achieve fast leg extensions for running and jumping. Here, the working principle of the articular membrane covering the spider leg joint pit is investigated. This membrane is highly involved in walking, grasping, and jumping motions. Hardness and stiffness of the articular membrane is studied using nanoindentation tests and preparation methods for scanning electron microscopy and histology are developed to give detailed information about the inner and outer structure of the leg joint and its membrane. Inspired by the stroller umbrella‐like folding mechanism of the articular membrane, a robust thermoplastic polyurethane‐based rotary semifluidic actuator is demonstrated, which shows increased durability, achieves working angles over 120°, produces high torques which allows lifts over 100 times of its own weight and jumping abilities. The developed actuator can be used for future grasping tasks, safe human–robot interactions and multilocomotion ground robot applications, and it can shed light into spider locomotion‐related questions.

Slow recovery of T-cell numbers and function contributes to the high incidence of life-threatening infections after cytotoxic cancer therapies. We have tested the therapeutic potential of a novel class of superagonistic CD28-specific antibodies that induce polyclonal T-cell proliferation without T-cell receptor engagement in an experimental rat model of T lymphopenia.We show that in lethally irradiated, bone marrow-reconstituted hosts, CD28 superagonist is able to dramatically accelerate repopulation by a small inoculum of mature, allotype-marked T cells. CD28-driven recovery of CD4 cells was superior to that of CD8 T cells. CD28 superagonistexpanded CD4 T cells had maintained repertoire diversity and were functional both in vitro and in vivo, suggesting that treatment with a human CD28-specific superagonist will protect T-lymphopenic patients from opportunistic infections.