Immunology Faculty Member - Arlene Sharpe, MD, PhD

Arlene Sharpe, MD, PhD

Harvard Medical School
NRB, Room 837
77 Avenue Louis Pasteur
Boston, MA 02115
Tel: 617-432-6568
Fax: 617-432-6570
Visit my lab page here.

The major interest of the Sharpe laboratory is to study functions of T cell costimulatory pathways and their immunoregulatory roles in controlling the balance between T cell activation and tolerance. Costimulation is of therapeutic interest because manipulation of T cell costimulatory pathways may provide a means either to enhance immune responses (to promote anti-microbial or tumor immunity) or terminate immune responses (to control autoimmune diseases or achieve tolerance for tissue transplantation).

The Sharpe laboratory has used genetic approaches to determine the obligatory functions of T cell costimulatory pathways. This research has provided novel insights and revealed unexpected functions of costimulatory pathways in the B7:CD28 family of costimulatory For example, we have found a critical role for the CD28 homolog ICOS in regulating T cell dependent B cell responses, and the development of several CD4 T cell lineages. Our studies in the PD-1:PD-1 ligand pathway have shown that PD-L1 and PD-L2 are ligands for PD-1 and can inhibit naïve and effector T cells. Further work demonstrated a novel role for PD-L1 on parenchymal cells in regulating self-reactive T cells. Additional studies indicate that PD-1 and PD-L1 inhibit T cell function during chronic viral infection and blockade of this pathway can restore function of “exhausted” T cells. These findings have revealed a new therapeutic strategy for chronic viral infection. We also have identified B7-1 and PD-L1 as binding partners and shown that their interaction inhibits T cell responses. The identification of this new pathway give increased significance to B7-1 and PD-L1 on T cells, and compels a reassessment of pathways in the B7:C28 family in regulating T cell activation and tolerance.

Current areas of interest in the lab include defining roles of costimulatory and coinhibitory pathways in regulating the balance between pathogenic and protective T cell responses in mouse models of infection and autoimmunity. We are using conditional gene targeting approaches to define the function of coinhibitory receptors on regulatory, effector and memory T cells (as well as other cell types). We also are defining unique and synergistic functions of costimulatory and coinhibitory pathways (e.g., PD-1, CTLA-4, CD160, CD244). Finally we are beginning to examine how costimulatory and coinhibitory functions in T cells change with with age.

Last Update: 12/17/2018


Juneja VR, McGuire KA, Manguso RT, LaFleur MW, Collins N, Haining WN, Freeman
GJ, Sharpe AH. PD-L1 on tumor cells is sufficient for immune evasion in
immunogenic tumors and inhibits CD8 T cell cytotoxicity. J Exp Med. 2017 Apr
3;214(4):895-904. doi: 10.1084/jem.20160801. Epub 2017 Mar 16. PubMed PMID:
28302645; PubMed Central PMCID: PMC5379970.

Sage PT, Ron-Harel N, Juneja VR, Sen DR, Maleri S, Sungnak W, Kuchroo VK,
Haining WN, Chevrier N, Haigis M, Sharpe AH. Suppression by T(FR) cells leads to
durable and selective inhibition of B cell effector function. Nat Immunol. 2016
Dec;17(12):1436-1446. doi: 10.1038/ni.3578. Epub 2016 Oct 3. PubMed PMID:
27695002; PubMed Central PMCID: PMC5502675.

Paterson AM, Lovitch SB, Sage PT, Juneja VR, Lee Y, Trombley JD,
Arancibia-Cárcamo CV, Sobel RA, Rudensky AY, Kuchroo VK, Freeman GJ, Sharpe AH.
Deletion of CTLA-4 on regulatory T cells during adulthood leads to resistance to
autoimmunity. J Exp Med. 2015 Sep 21;212(10):1603-21. doi: 10.1084/jem.20141030.
Epub 2015 Sep 14. PubMed PMID: 26371185; PubMed Central PMCID: PMC4577848

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