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Mikael J. Pittet, PhD

Associate Professor, Department of Radiology, Harvard Medical School

Contact Info

Mikael Pittet
Massachusetts General Hospital
185 Cambridge St

Boston, MA, 02114
Mailstop: Simches Rm 5228
Phone: 617-643-6285


Not Available.

DF/HCC Program Affiliation

Cancer Immunology
Cancer Imaging

Lab Website

Pittet Lab

Research Abstract

My laboratory studies responses mediated by innate and adaptive immune cells. We look at how these cells interplay, respond to stimuli and exhibit regulatory or effector functions. Because in vitro readouts do not always recapitulate the complexity of in vivo environments, the discovery effort utilizes noninvasive, three-dimensional bioimaging technologies combined with novel cell trackers and molecular sensors. The modalities provide either real-time microscopic cellular resolution, quantitative whole organ information and/or have translational potential. Our goals are to develop approaches for comprehensive investigation of cell types in defined microenvironments, and to quantify and model information obtained by bioimaging. As detailed below, we have focused our efforts on the study of adaptive immune responses mediated by T cells, and innate immune responses mediated by mononuclear phagocytes.

ADAPTIVE IMMUNE CELLS. T cells are specialized to recognize cells infected with intracellular pathogens or transformed cells expressing tumor-associated antigens. Cytotoxic T cells (CTL) execute their effector functions during direct physical interactions with their targets, which include release of lytic granules and secretion of cytokines. In contrast other T cells such as T regulatory (Treg) cells mediate dominant suppressive functions and can prevent the activity of CTL and other effector cells. Our understanding of how immune functions are regulated and integrated in vivo at the cellular level is, to a large extent, still speculative. We are studying how Treg cells repress CTL responses in vivo, and whether Treg cell-mediated tolerance can be reversed in therapy.

INNATE IMMUNE CELLS. Mononuclear phagocytes exert crucial functions as scavengers and can trigger or regulate immune responses. Recent studies indicate that monocytes - the precursors of macrophages and dendritic cells - comprise separate subsets that 'commit' to specific functions. The activity of these subsets in vivo is largely unknown. We are studying tissue tropism, cellular differentiation and role in immunity of monocyte subsets in various inflammatory conditions. We are also testing whether these cells are potential targets in therapy.


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