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The ability to monitor anti-tumor CD8+ T cell responses in the blood has tremendous therapeutic potential. Here, we used paired single-cell RNA and TCR sequencing to detect and characterize "tumor-matching" (TM) CD8+ T cells in the blood of mice with MC38 tumors or melanoma patients using the TCR as a molecular barcode. TM cells showed increased activation compared with nonmatching T cells in blood and were less exhausted than matching cells in tumors. Importantly, PD-1, which has been used to identify putative circulating anti-tumor CD8+ T cells, showed poor sensitivity for identifying TM cells. By leveraging the transcriptome, we identified candidate cell surface markers for TM cells in mice and patients and validated NKG2D, CD39, and CX3CR1 in mice. These data show that the TCR can be used to identify tumor-relevant cells for characterization, reveal unique transcriptional properties of TM cells, and develop marker panels for tracking and analysis of these cells.

Background Study Design Results Conclusion Granulocyte transfusions represent a therapeutic option for severely neutropenic patients with bacterial or fungal infections that are otherwise unresponsive to conventional therapy. Prior clinical studies suggest that patients receiving higher granulocyte doses achieve superior outcomes. Consequently, suboptimal donor stimulation and collection leading to lower granulocyte doses likely correlate with worse clinical outcomes.A retrospective analysis was conducted on mobilisation data from 312 granulocyte collections from healthy donors between January 2020 and May 2023. This study was performed in a single blood donor center exclusively supporting a comprehensive cancer center. Donors underwent stimulation with 480 mcg of filgrastim (granulocyte colony stimulating factor [G‐CSF]) subcutaneously and 8 mg of dexamethasone orally administered 12 to 14 h before collection. The correlation between donor characteristics (age, gender, body weight (BW), body mass index (BMI), baseline haemoglobin (Hgb), and platelet (PLT) counts) and mobilisation efficiency (Δ WBC, defined as post‐mobilisation WBC count—baseline WBC count) was examined to identify factors associated with enhanced mobilisation efficiency. Additionally, the impact of multiple donations on Δ WBC in repeat donors was assessed.The median donor age was 43 years (range 18–81), with 224 male and 88 female donors. Female donors exhibited significantly higher baseline PLT counts and post‐mobilisation WBC counts. However, donor gender did not significantly affect Δ WBC. A negative correlation was observed between Δ WBC and age (r = −0.235, p = 0.001), with older donors (61–81 years) exhibiting significantly lower mobilisation efficiency. BW and BMI differences had no significant effect on Δ WBC. A positive correlation was identified between baseline PLT count and Δ WBC (r = 0.140, p = 0.014), with females having significantly higher baseline PLT counts (p = 0.0004). No correlation was found between Δ WBC and baseline Hgb (r = 0.004, p = 0.477). Repeat donors showed no statistically significant change in Δ WBC with subsequent donations, with a mean interval of 136.5 days between collections.Mobilisation efficiency was not impacted by donor BW or BMI suggesting that BW‐based G‐CSF stimulation is not essential for optimising WBC mobilisation. Rather, a fixed single dose of 480 mcg of G‐CSF and 8 mg of dexamethasone was sufficient to mobilise donors, thus reducing the procedural costs and the potential risks for medication‐related side effects. The positive correlation found between baseline PLT count and Δ WBC suggests that PLT count could be used as a potential predictor of mobilisation efficiency. Mobilisation response in up to four collections in repeat granulocytes donors was not affected in subsequent donations. However, sample size is a limitation, and more data is needed for a meaningful conclusion of whether frequent granulocyte donations are safe and effective. [ABSTRACT FROM AUTHOR]

Our current understanding of immunology was largely defined in laboratory mice, partly because they are inbred and genetically homogeneous, can be genetically manipulated, allow kinetic tissue analyses to be carried out from the onset of disease, and permit the use of tractable disease models. Comparably reductionist experiments are neither technically nor ethically possible in humans. However, there is growing concern that laboratory mice do not reflect relevant aspects of the human immune system, which may account for failures to translate disease treatments from bench to bedside (1-8). Laboratory mice live in abnormally hygienic specific pathogen free (SPF) barrier facilities. Here we show that standard laboratory mouse husbandry has profound effects on the immune system and that environmental changes produce mice with immune systems closer to those of adult humans. Laboratory mice--like newborn, but not adult, humans--lack effector-differentiated and mucosally distributed memory T cells. These cell populations were present in free-living barn populations of feral mice and pet store mice with diverse microbial experience, and were induced in laboratory mice after co-housing with pet store mice, suggesting that the environment is involved in the induction of these cells. Altering the living conditions of mice profoundly affected the cellular composition of the innate and adaptive immune systems, resulted in global changes in blood cell gene expression to patterns that more closely reflected the immune signatures of adult humans rather than neonates, altered resistance to infection, and influenced T-cell differentiation in response to a de novo viral infection. These data highlight the effects of environment on the basal immune state and response to infection and suggest that restoring physiological microbial exposure in laboratory mice could provide a relevant tool for modelling immunological events in free-living organisms, including humans., Given reported species-specific differences in immune responses (1-8), we compared the distribution and differentiation of memory [CD8.sup.+] T cells between mice and humans. [CD8.sup.+] T cells are crucial for adaptive [...]

CD4-unhelped CD8+ T cells are functionally defective T cells primed in the absence of CD4+ T cell help. Given the co-stimulatory role of natural-killer group 2, member D protein (NKG2D) on CD8+ T cells, we investigated its ability to rescue these immunologically impotent cells. We demonstrate that augmented co-stimulation through NKG2D during priming paradoxically rescues memory, but not effector, CD8+ T cell responses. NKG2D-mediated rescue is characterized by reversal of elevated transcription factor T-box expressed in T cells (T-bet) expression and recovery of interleukin-2 and interferon-g production and cytolytic responses. Rescue is abrogated in CD8+ T cells lacking NKG2D. Augmented co-stimulation through NKG2D confers a high rate of survival to mice lacking CD4+ T cells in a CD4-dependent influenza model and rescues HIV-specific CD8+ T cell responses from CD4-deficient HIV-positive donors. These findings demonstrate that augmented co-stimulation through NKG2D is effective in rescuing CD4-unhelped CD8+T cells from their pathophysiological fate and may provide therapeutic benefits., Memory CD8+ T cells confer efficient and long-lasting immunity against secondary pathogen exposure(1,2). Events during primary expo-sure (priming) affect the quality of the initial effector and subsequent memory cytotoxic T [...]

Despite the success of monotherapies based on blockade of programmed cell death 1 (PD-1) in human melanoma, most patients do not experience durable clinical benefit. Pre-existing T-cell infiltration and/or the presence of PD-L1 in tumours may be used as indicators of clinical response; however, blood-based profiling to understand the mechanisms of PD-1 blockade has not been widely explored. Here we use immune profiling of peripheral blood from patients with stage IV melanoma before and after treatment with the PD-1-targeting antibody pembrolizumab and identify pharmacodynamic changes in circulating exhausted-phenotype CD8 T cells (T[sub.ex] cells). Most of the patients demonstrated an immunological response to pembrolizumab. Clinical failure in many patients was not solely due to an inability to induce immune reinvigoration, but rather resulted from an imbalance between T-cell reinvigoration and tumour burden. The magnitude of reinvigoration of circulating T[sub.ex] cells determined in relation to pretreatment tumour burden correlated with clinical response. By focused profiling of a mechanistically relevant circulating T-cell subpopulation calibrated to pretreatment disease burden, we identify a clinically accessible potential on-treatment predictor of response to PD-1 blockade., Author(s): Alexander C. Huang (corresponding author) [1, 2, 3, 4]; Michael A. Postow [5, 6]; Robert J. Orlowski [1, 2, 3, 4]; Rosemarie Mick [3, 4, 7]; Bertram Bengsch [2, [...]