Natural killer (NK) cells are defined as a population of lymphoid cells able to recognize and kill certain tumors and virally infected cells in vitro. Also they have been implicated in the rejection of allogeneic bone marrow grafts. They express an allelic surface marker called NK1.1, and they share early progenitors with T and/or B cells. They can also secrete cytokines as IFN-g, TNF-a, and IL-12. The nature of the NK recognition is not completely clear, it occurs without previous sensitization, and affects preferentially MHC class I-negative or disparate target cells.

The research in my laboratory is focused on the study of development and function of the NK cell compartment in mouse. I have divided my research in three areas:

1. Precursors and lineage commitment to NK cell compartment. NK cells are derived from hematopoietic stem cells (HSC), but their pathways of commitment have not been fully established. I am studying the generation of NK1.1 cells from purified HSC, evaluating the appearance of donor derived NK cells with respect to other lineages, and the influence of thymus on the generation of NK1.1 populations. These experiments have shown that NK cells appear early, independently of T cells, and the presence of thymus.

With the aim of identifying NK cell precursors; using in vitro systems to support the differentiation to NK cells from isolated bone marrow cell populations, I have been able to identify cellular entities with NK progenitor activity. These candidate progenitor activities will be testedin vivo in competitive repopulation assays.

2. Phenotypic and functional heterogeneity in the NK cell compartment. NK cells can express different lineage and MHC recognition markers. Functionally, it is not clear if the cytotoxic ability of NK cells vs. their ability to secrete cytokines represent a functional commitment or cells can have a dual function. I have generated monoclonal antibodies that can recognize subpopulations of NK1.1 cells. These are being analyzed by their effect on NK cell recognition and cytotoxic function, and to dissect the NK cell population in conjunction with other lineage markers. Sorted NK cells are analyzed for cytotoxic activity and for the expression of cytokine by RT-PCR, and cytofluotometry .

3. Role of NK cells in asthma. Recent evidence have shown that NK cells can be participants in the induction and/or maintenance of allergic asthma in a murine asthma model. We are using a variety of methods, including antibody immunodepletion, and a several types of NK cell deficient mice to understand how asthma could be modulated by NK cells. We are also working on generating NK cell lines with the aim of using them in immunotherapy treatments.

Lab Rotation Projects:
A. Evaluate engraftment of Hematopoietic Stem Cells (HSCs) and their developmental progression potential after transplantation into recipients in which osteoblasts have been depleted. We have shown that hematopoiesis is dependent on a correct microenvironment in the bone marrow and that disruption of the microenvironment by selectively depleting osteoblasts (bone forming cells) alters hematopoiesis and allows the engraftment of exogenously injected hematopoietic progenitors. We would like to compare this treatment with more traditional myeloablation methods (irradiation) on syngeneic as well as allogeneic purified HSCs transplants.

B. Identification and isolation of lymphoid progenitors with the ability to generate NK and NK/T cells. NK and NK/T cells are lymphoid cells consider as part of the innate immune system. Using flow cytometry we have fractionated bone marrow cells and characterized several phenotypes with the potential to generate NK cells. We would like to test how exclusive these populations are for the generation of NK cells compared to B and/or T cells. most of the techniques are based on developmental assays in culture.

Selected Publications: