Robert B. Levy, Ph.D.

Professor of Microbiology and Immunology
Room 720, McKnight Building
1638 NW 10 Avenue
Telephone: 305-243-4542
Lab: 305- 243-6215
Fax: 305- 243-6903
Email: rlevy@med.miami.edu

Research Interests:

T-Cells in Bone Marrow Transplantation and Cancer .

Graft vs. Host Disease (GVHD) in models of allogeneic bone marrow transplantation (BMT)

BMT has been employed for the reconstitution and treatment of patients with a variety of both hematopoietic disorders as well as solid tissue tumors. GVHD remains the major obstacle to more widespread application of BMT. We are examining the role of donor T cells and their effector function in the development of GVHD. Our approach is to employ donor T cells and recipients with specific deficits in cytotoxic signaling pathways to examine effector mechanisms responsible for the induction and tissue damage occurring in GVHD. The studies have begun to identify molecules which are important in particular GVHD target tissues. We have learned that FasL-Fas interactions between allogeneic donor cells and host populations play important roles in the development of tissue damage in the skin and liver and are also important in the development of chimerism post-BMT. In addition, we have found that perforin presence is associated with more rapid onset of pathogenesis and death in allogeneic BMT recipients. Recent studies using highly enriched T cell subsets have demonstrated a crucial role for donor cytotoxicity early post-BMT, prior to tissue damage. Together with the use of recipient “knock-out” mice defective in receptors for other death inducing pathways (ex. TNF R1 and R2), present studies are examining how non-perforin and non-FasL effector pathways contribute to GVHD.

Rejection of the marrow graft: The ‘barrier’ against stem cell and progenitor cell engraftment post-BMT

Unfortunately, removal of T cells to prevent GVHD dramatically increases the frequency of stem cell rejection. To inhibit resistance against stem cell engraftment, recipients must be conditioned to suppress immune rejection. As novel conditioning regimens which are less myeloablative are developed to expand future BMT applications, there is increasing concern about controlling such resistance. We are studying in vivo and in vitro model systems to identify effector pathways and molecules which are utilized in recipients to effect barrier activity. CD8+ T cells with known barrier activity have been identified in one model system. Interestingly, we found that CD8+ cells from ‘double’ (granule and FasL) cytotoxically defective mice can effect resistance - demonstrating that other effector pathways must be capable of interfering with engraftment. We are developing in vitro systems using highly purified stem cells together with effector cells to investigate potential pathways. The ability to selectively target and inhibit specific molecules in recipients to abrogate barrier activity should support efficient engrafment and enable removal of donor T cells from the transplant to prevent GVHD.

Immunotherapy for Leukemia

The infusion of T cells with anti-tumor specificity is being investigated as an immunotherapeutic approach to treat various cancers. We are interested in generating human T cells reactive against peptides of proteins which are over-expressed in tumors including leukemias. The expression of anti-apoptotic proteins has been proposed as contributory to the survival of some populations of tumor cells. To test the hypothesis that elimination of surviving clones of tumor cells following chemo and radiation therapy can be targeted through recognition of peptide moieities of these proteins, an initial objective is to develop CD8+ T cells against selected synthetic peptides from anti-apoptotic proteins (i.e.bclx). We are also developing experimental tumor models to study how immunization against tumor antigens, bone marrow transplantation and application of anti-tumor reactive T cells can function in vivo with respect to prolonging survival and curing disease.

Research Group:

The "Lab": April 2006

• Melinda Roskos, Ph.D. / M.D. student
• Alwi Shatry, Ph.D. Assistant Professor
• Monica Jones, Research Associate
• Maitee Urbieta, Rotating Graduate Student
• Jason Wilt, Technician
• Michael Miller, Technician

Zhe Jiang, Ph.D. student - Awarded Ph.D. May, 2001. Research Scientist at Sunol Corporation, Miramar, Florida

Selected Publications:

Adeegbe, D., Bayer, AL., Levy, RB., and TR. Malek. Adoptive therapy with allogeneic T regulatory cells suppresses autoimmunity and leads to transplantation tolerance. J.Immunol. in press 2006

Barao, I., Hanash, AM., Hallet, W., Welniak, L.A., Sun, K Redelman, D., Blazaar, BR., Levy, RB. and W.J. Murphy. Suppression of NK cell-mediated bone marrow cell rejection by CD4+CD25+ regulatory T cell: linkage of adaptive to innate responses in transplantation. PNAS, 103:5460-5464, 2006.

Hanash, A and R.B. Levy. Donor CD4+CD25+ T cells promote engraftment and tolerance following MHC-mismatched HCT. Blood 105:1828-36, 2005.

Zimmerman, Z., Shatry, Deyev, V., Podack, ER, Blazar, B., Yagita, Mamolenti, M. and R.B. Levy. Rapid resistance against allogeneic progenitor cell grafts is independent of perforin, FasL, TNFR1, TRAIL, DR3 and TWEAK dependent effector pathways. Biol. Blood and Marrow Transpl. 11:576-586, 2005.

Zachary Zimmerman, Monica Jones, Alwi Shatry, Masanobu Komatsu Michele Mammolenti and Robert B. Levy. Cytolytic pathways used by effector cells derived from recipient naive and memory T cells and natural killer cells in resistance to allogeneic hematopoietic cell transplantation. Biol. Blood and Marrow Transpl. Review Article. 11:957-971, 2005.

Levy, RB. GVHD: Complication and Challenge to Successful Allogeneic Hematopoietic Cell Transplantation. Invited review, Current Medical Chemistry-Immunology, Endocrine and Metabolic Agents. 5:585-597, 2005.

Jiang, Z., Podack, E.R., and Levy, R.B. Allogeneic BMT using perforin and FasL double-defective donor T cells: A crucial role for cytotoxic function by donor lymphocytes prior to pathogenesis. Blood, 98:390-397, 2001.

Jones, M., Komatsu, M., and Levy, R.B. Cytotoxically impaired transplant recipients can efficiently resist major histocompatibility complex-matched bone marrow allografts. Biol. Bl. Mar. Transp. 6:456-464, 2000.

Ferrara, J.L.M., Levy, R.B. and Chao, N.F. Pathophysiologic mechanisms of acute graft-vs.-host disease. Biol. Bl. Mar. Transp. 5:347-356, 1999 .

Baker, M.B., Riley, R.L., Podack, E.R., and Levy, R.B. GVHD-associated lymphoid hypoplasia and B cell dysfunction is dependent upon donor T cell-mediated Fas-ligand function, but not perforin function. Proc. Natl. Acad. Sci., 94:1366-1371, 1997 .