Transplant Immunology

Associate Professor
Department of Surgery
Program in Immunology

Education:

Ph.D., University of California, Davis
Postdoctoral Fellowship, University of California, San Francisco

Research Interests:

We have begun studies directed at elucidating the roles of microRNAs in transplantation. After profiling global miRNA expression in human small bowel biopsy, we discovered that unsupervised hierarchical clustering of microRNA patterns could distinguished rejecting from non-rejecting biopsies. Liver transplant outcome is also significantly affected by viral recurrence or reactivation in the post-transplant period, in part exacerbated by the immunosuppressed status of the host immune system. We have developed a model using rat orthotopic liver transplantation and total lymphoid irradiation (TLI) to study the immune mechanisms of tolerance induction in liver allograft recipients. Our studies suggest that concomitant viral infection can augment alloimmune responses in liver allograft recipients and can perturb the immune regulatory mechanisms that promote tolerance. Our studies have challenged the paradigm that NK cells do not participate in the rejection of solid organ grafts. We have demonstrated that recipient-derived NK cells not only infiltrate rejecting liver grafts early after transplantation but also are a significant source of IFNg thus bridging the innate and adaptive immune responses post transplant. We examined the activation receptors involved in the interaction of NK cells with dendritic cells (DC) since NK cells have the potential to mediate both maturation and killing of DC and this could alter T cell priming post-tarnsplant. Using RNAi techniques we demonstrated that DC stimulation of NK cells to produce IFNg is mediated through NKp46 and that NK cell killing of DC is independent of NKp30, NKp46 and NKG2D. Our studies indicate that NK cells interact with DC and tumors through distinct activating receptors – NKp46 and NKp30/NKG2D respectively. These data are important for the development of therapeutics that will target NK-DC interactions post-transplant without compromising the ability of NK cells to kill virally-infected or transformed cells.

Professor
Department of Surgery
Program in Immunology

Education:

Ph.D., University of California, Berkeley

Research Interests:

I have two major areas of focus in the laboratory. First, I am interested in Epstein Barr Virus-mediated mechanisms of immune evasion with particular focus on resistance to cell death receptor pathways of apoptosis in EBV B cell lymphomas, the characterization of the human T cell response to EBV infected B cells, host microRNAs induced by EBV infection and effects of immunosuppressive drugs on growth and survival of EBV B cell lymphomas. The second area of study addresses tolerance induction in solid organ transplantation. Specifically, examining the generation and characterization of regulatory T cells in allogeneic responses and the role of alternate co-stimulatory molecules in alloreactivity.

Professor of Surgery
Chief, Division of Transplantation
Director, Liver Transplant Program

Education:

Research Interests:

The molecular mechanisms of rejection
Induction of tolerance to achieve full acceptance of transplanted organs

Mary Gay Lapasaran, MD

Life Science Research Professional 2
Clinical Research Coordinator
Lab Manager

Education:

Research Interests:

I handle the clinical studies mainly involving immune mechanisms of certain viruses in transplant recipients in children and adults. To be able to interact with patients and their family and to be able to contribute to a better understanding to cure or treat certain diseases has always been why research has been of importance to me.

Yarl Balachandran, MD

Surgical Resident
Postdoctoral Scholar in Transplantation Surgery

Education:

Research Interests:

Post-Transplant Lymphoproliferative Disorder (PTLD) is the most common malignancy in children who have undergone solid organ transplantation and are on chronic immunosuppression. The lack of proven biomarkers to reliably identify PTLD or those patients at highest risk has hindered advances in the field. Given this, my research is focused on investigating possible biomarkers for PTLD. In particular, I assess gain-of-function mutations in the Epstein-Barr virus (EBV) protein LMP1 and identify microRNAs associated with EBV-positive PTLD. I also assist with the ongoing NIH-funded Clinical Trials in Organ Transplantation in Children (CTOT-C) study. I was recently invited to present at the NIH and American Transplant Congress.

Marla McPherson, PhD

Postdoctoral Researcher

Education:

Research Interests:

Marc Lucia Perez, PhD

Postdoc

Education:

Research Interests:

I am interested in studying the TCR and BCR repertories and its possible use as a Biomarker for immunological related events in the context of Solid Organ transplantation.

James Harden

PhD Student, Immunology

Education:

Research Interests:

I use a murine cardiac allograft transplant model to study mechanisms of immune suppression that facilitates allograft prolongation and prevents rejection. My current focus is on the immunosuppressive contribution of hepatic plasmacytoid dendritic cells (pDC) and the role of miR-181 in pDC function.

Eden Maloney

PhD Candidate, Immunology

Education:

Research Interests:

Research Description: I'm using deep-sequencing to create a genomic atlas of EBV to reveal how EBV genomic diversity varies in health and disease, specifically how EBV contributes to oncogenesis. Additionally, I am using bioinformatics to understand how EBV contributes to cancer in various tissue types.

Jiaying Toh

PhD Student, Immunology

Education:

Research Interests:

Research Description: Interactions between EBV+ PTLD and the immune system.

Undergraduate Student, Stanford University

Stanford Institutes of Medicine Summer Research Program
Undergraduate Student, Brown University

Stanford Summer Research Program
Undergraduate Student, St. Mary's University - San Antonia, Texas

Medical Student, Stanford University School of Medicine
Bachelor's Degree, Biology Concentrated in Biochemistry, Middle Eastern Studies