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Mature immunocompetent cells from the stem cell graft as well as early robust immune reconstitution are essential for the graft-vs. -tumor (GVT) effect to eliminate residual malignant cells after allogeneic hematopoietic stem cell transplantation (HSCT). In this prospective study we characterized graft composition of T- and NK cell subsets in 88 recipients of peripheral blood stem cell grafts with multicolor flowcytometry. Our primary aim was to analyze the impact of graft composition on immune reconstitution and clinical outcomes after transplantation. Patients transplanted with graft NK cell doses above the median value of 27 × 106/kg had significantly increased relapse-free-survival compared to patients transplanted with lower doses, HR 2.12 (95% CI 1.01–4.45, p = 0.04) Peripheral blood concentrations of NK cells obtained from donors before G-CSF mobilization were significantly correlated to graft NK cell doses (Spearman's ρ 0.53, p = 0.03). The dose of transplanted NK cells/kg correlated significantly with NK cell concentrations in patients early after transplantation (Spearman's ρ 0.26, p = 0.02, and ρ = 0.35, p = 0.001 for days 28 and 56, respectively). Early immune reconstitution above median values of NK cells was significantly associated with improved relapse-free survival (HR 2.84 [95% CI 1.29–6.28], p = 0.01, and HR 4.19 [95% CI 1.68–10.4], p = 0.002, for day 28 and 56, respectively). Early concentrations above the median value of the mature effector CD56dim NK cell subset were significantly associated with decreased relapse incidences at 1 year, 7% (95% CI 1.8–17) vs. 28% (95% CI 15–42), p = 0.04, and 7% (95% CI 1.8–18) vs. 26% (95% CI 14–40) %, p = 0.03, for days 28 and 56, respectively. The results suggest a protective effect of high doses of NK cells in grafts and during early immune reconstitution and support the perception of NK cells as innate effector cells with anti-tumor effects in the setting of allogeneic stem cell transplantation.

Mature immunocompetent cells from the stem cell graft as well as early robust immune reconstitution are essential for the graft-vs. -tumor (GVT) effect to eliminate residual malignant cells after allogeneic hematopoietic stem cell transplantation (HSCT). In this prospective study we characterized graft composition of T- and NK cell subsets in 88 recipients of peripheral blood stem cell grafts with multicolor flowcytometry. Our primary aim was to analyze the impact of graft composition on immune reconstitution and clinical outcomes after transplantation. Patients transplanted with graft NK cell doses above the median value of 27 × 106/kg had significantly increased relapse-free-survival compared to patients transplanted with lower doses, HR 2.12 (95% CI 1.01–4.45, p = 0.04) Peripheral blood concentrations of NK cells obtained from donors before G-CSF mobilization were significantly correlated to graft NK cell doses (Spearman's ρ 0.53, p = 0.03). The dose of transplanted NK cells/kg correlated significantly with NK cell concentrations in patients early after transplantation (Spearman's ρ 0.26, p = 0.02, and ρ = 0.35, p = 0.001 for days 28 and 56, respectively). Early immune reconstitution above median values of NK cells was significantly associated with improved relapse-free survival (HR 2.84 [95% CI 1.29–6.28], p = 0.01, and HR 4.19 [95% CI 1.68–10.4], p = 0.002, for day 28 and 56, respectively). Early concentrations above the median value of the mature effector CD56dim NK cell subset were significantly associated with decreased relapse incidences at 1 year, 7% (95% CI 1.8–17) vs. 28% (95% CI 15–42), p = 0.04, and 7% (95% CI 1.8–18) vs. 26% (95% CI 14–40) %, p = 0.03, for days 28 and 56, respectively. The results suggest a protective effect of high doses of NK cells in grafts and during early immune reconstitution and support the perception of NK cells as innate effector cells with anti-tumor effects in the setting of allogeneic stem cell transplantation. [ABSTRACT FROM AUTHOR]

Innate effector cells, including innate effector cells of myeloid and lymphoid lineages, are crucial components of various types of immune responses. Bone marrow progenitors differentiate into many subsets of innate effector cells after receiving instructional signals often provided by cytokines. Signal transducer and activator of transcription (STATs) have been shown to be essential in the differentiation of various types of innate effector cells. In this review, we focus specifically on the differentiation of innate effector cells, particularly the role of cytokine signaling in the differentiation of innate effector cells. [ABSTRACT FROM AUTHOR]

Therapeutic strategies aiming at mobilizing immune effector cells to kill tumor cells independent of tumor mutational load and MHC expression status are expected to benefit cancer patients. Recently, we engineered various peptide-Fc fusion proteins for directing Fcg receptor-bearing immune cells toward tumor cells. Here, we investigated the immunostimulatory and anti-tumor effects of one of the engineered Fc fusion proteins (WN-Fc). In contrast to the Fc control, soluble WN-Fc-1 fusion protein activated innate immune cells (e.g. monocytes, macrophages, dendritic cells, NK cells), resulting in cytokine production and surface display of the lytic granule marker CD107a on NK cells. An engineered Fc-fusion variant carrying two peptide sequences (WN-Fc-2) also activated immune cells and bound to various cancer cell types with high affinity, including the murine 4T1 breast carcinoma cells. When injected into 4T1 tumor-bearing BALB/c mice, both peptide-Fc fusions accumulated in tumor tissues as compared to other organs such as the lungs. Moreover, treatment of 4T1 tumor-bearing BALB/c mice by means of two intravenous injections of the WN-Fc fusion proteins inhibited tumor growth with WN-Fc-2 being more effective than WN-Fc-1. Treatment resulted in tumor infiltration by T cells and NK cells. These new engineered WN-Fc fusion proteins may be a promising alternative to existing immunotherapies for cancer.