Although NK cells are considered part of the innate immune system, a series of evidences has demonstrated that they possess characteristics typical of the adaptive immune system. These NK adaptive features, in particular their memory-like functions, are discussed from an ontogenetic and evolutionary point of view.

Cytotoxic functions and susceptibility to apoptosis are crucial aspects of NK cells suitable to counter cancer after infusion in oncologic patients. To test the feasibility and the usefulness of infusing in vitro generated NK cells, these two features were investigated in NK cells developed in vitro from CD34 1 hematopoietic progenitors. Purified CD34 The NK functional activities and the end of NK cell responses are finely controlled by NK cell receptors (NKRs) with activatory and inhibitory functions. To this regard, NK cells express inhibitory receptors for MHC class I (MHC-I) molecules, the killer cell immunoglobulin (Ig)-like receptors (KIRs) and C-type lectin CD94-CD159a, which are able to block activatory signals. These latter signals are mainly triggered by CD16, natural cytotoxicity receptors (NCRs), NKG2D, and the leukocyte adhesion molecule DNAM-1 (CD226) (1,2). On the other hand, TNF ligand and receptor members are also involved both in NK cell-mediated cytotoxic function and in the control of NK cell response (3, reviewed in Ref. 4).Within the NK compartment, two phenotypically and functionally distinct NK subsets, CD56 bright and CD56 dim , have been described to represent either different stages of NK cell differentiation (Stage 4 and 5, respectively) or different subpopulations (similarly to CD4 and CD8 T cells, respectively) (2,5). In particular, CD56 dim / CD16 bright /CD117 neg NK cells are highly cytotoxic and preferentially express KIR inhibitory receptors, while the cytokine-producer CD56 bright NK cells are characterized by CD117 (c-kit) cytokine receptor and CD94-CD159a inhibitory receptor, although

EPR analysis revealed peculiar structural and dynamical properties of anticancer-activeG3B–Cu(ii) in absence and presence of normal and cancer cells.

Milk is a complex fluid required for development, nutrition and immunological protection to the newborn offspring. Interestingly, latest finding proved the presence of novel stem cell population in human milk with multilineage differentiation potential. Given that little is known about cellular milk content in other mammalian species such as bovine, the purpose of our study was to isolate and characterize a potential stem cell-like population in bovine milk. In detail, we first analyzed the phenotype of the isolated cells able to grow in plastic adherence and then their capability to differentiate into osteogenic, chondrogenic, and adipogenic lineages. Bovine milk stem cells (bMSCs) resulted plastic adherent and showed a heterogeneous population with epithelial and spindle-shaped cells. Successively, their immunophenotype indicated that bovine milk cells were positive for the typical epithelial markers E-cadherin, cytokeratin-14, cytokeratin-18, and smooth muscle actin. Notably, a subset (30%-40%), constantly observed in purified milk cells, showed the typical mesenchymal surface antigens CD90, CD73, and CD105. Furthermore, the same percentage of bMSCs expressing CD90, CD73, and CD105 presented the stemness markers SOX2 and OCT4 translocated in their nuclei. Finally, our data showed that bMSCs were able to differentiate into osteoblasts, chondroblasts, and adipocytes. In addition, the flow cytometry analysis revealed the presence of a subpopulation of events characterized by typical extracellular vesicles (EVs, size 0.1-1 μm), which did not contain nuclei and were positive for the same markers identified on the surface of bMSCs (CD73, CD90, and CD105), and thus might be considered milk cell-derived EVs. In conclusion, our data suggest that bovine milk is an easily available source of multipotent stem cells able to differentiate into multiple cell lineages. These features can open new possibilities for development biology and regenerative medicine in veterinary area to improving animal health.

The NK cell population is characterized by distinct NK cell subsets that respond differently to the various activating stimuli. For this reason, the determination of the optimal cytotoxic activation of the different NK cell subsets can be a crucial aspect to be exploited to counter cancer cells in oncologic patients. To evaluate how the triggering of different combination of activating receptors can affect the cytotoxic responses of different NK cell subsets, we developed a microbead-based degranulation assay. By using this new assay, we were able to detect CD107a+ degranulating NK cells even within the less cytotoxic subsets (i.e., resting CD56bright and unlicensed CD56dim NK cells), thus demonstrating its high sensitivity. Interestingly, signals delivered by the co-engagement of NKp46 with 2B4, but not with CD2 or DNAM-1, strongly cooperate to enhance degranulation on both licensed and unlicensed CD56dim NK cells. Of note, 2B4 is known to bind CD48 hematopoietic antigen, therefore this observation may provide the rationale why CD56dim subset expansion correlates with successful hematopoietic stem cell transplantation mediated by alloreactive NK cells against host T, DC and leukemic cells, while sparing host non-hematopoietic tissues and graft versus host disease. The assay further confirms that activation of LFA-1 on NK cells leads to their granule polarization, even if, in some cases, this also takes to an inhibition of NK cell degranulation, suggesting that LFA-1 engagement by ICAMs on target cells may differently affect NK cell response. Finally, we observed that NK cells undergo a time-dependent spontaneous (cytokine-independent) activation after blood withdrawal, an aspect that may strongly bias the evaluation of the resting NK cell response. Altogether our data may pave the way to develop new NK cell activation and expansion strategies that target the highly cytotoxic CD56dim NK cells and can be feasible and useful for cancer and viral infection treatment.