Michael Farrar, PhD

Professor and Virginia and David C. Utz Land Grant Chair in Fundamental Immunobiology, Department of Laboratory Medicine and Pathology

Michael Farrar

Contact Info


Office Phone 612-625-0401

Lab Phone 612-625-3608

Office Address:
Lab Medicine and Pathology
2-116 WMBB
2101 6th Street SE
Minneapolis, MN 55414

Mailing Address:
Center for Immunology
Department of Lab Medicine & Pathology
University of Minnesota
2101 6th Street SE
Minneapolis, MN 55414
Campus Delivery Code: 2641

PhD, Washington University School of Medicine (Immunology), 1993

BS, University of Wisconsin-Madison (Molecular Biology), 1987


Awards & Recognition

  • Cancer Research Institute Investigator Award, 2004 - 2008
  • Pew Scholar Award, 2002 - 2006
  • Rudolph M. Montgelas Cancer Research Institute Fellow, Cancer Research Institute, 1995 - 1997
  • Spencer T. and Ann W. Olin Medical Scientist Fellow, Olin Medical Scientist, 1992 - 1993
  • Phi Beta Kappa, 1986 - present

Professional Associations

American Association of Immunologists Member, 2000-present


Research Summary/Interests

Dr. Farrar holds the Virginia and David Utz Land Grant Chair in Fundamental Immunology, is a member of the Division of Molecular Pathology and Genomics, and is a member of the Center for Immunology.  His research is focused in three broad areas: B-cell development in the bone marrow and B-cell acute lymphoblastic leukemia (ALL), the developmental pathway of T regulatory cells, and cancer immunotherapy.

Farrar and his colleagues made a transgenic mouse that expresses a weakly constitutively active form of a transcription factor called STAT5b in B cells and T cells. During B-cell development in these mice they observed an expansion of B-cell progenitors. Some of these mice would develop B-cell ALL. Farrar and a colleague who studies the B-cell adapter protein BLNK that links the pre-B cell receptor to downstream signaling cascades found that nearly all transgenic mice with weakly expressed STAT5b and lacking BLNK developed B-cell ALL. The combination of crossbreeding experiments with transgenic STAT5b mice and the Sleeping Beauty transposon mutagenesis system enabled Farrar’s team to identify through crossing studies a number of key genes downstream of BLNK (BTK, protein kinase C beta, NF-?B) that cooperate with STAT5b. Key among these downstream genes is the zinc finger transcription factor Ikaros, a regulator of the earliest stage of B cell development. Farrar and his colleagues found that STAT5b and Ikaros, though separate signaling pathways, bind to the same sets of genes in mice. Subsequent analysis of activation ratios for the STAT5b and Ikaros pathways in human clinical specimens of ALL showed a correlation with patient survival and remission duration following treatment, demonstrating their potential
clinical importance.

Farrar’s STAT5b transgenic mice also show a major expansion of CD4-positive and FoxP3-positive regulatory T cells (Tregs), which provided the basis for a second research thrust. FoxP3 is a major transcription factor for the development of Tregs. In a major study Farrar and two of his colleagues demonstrated that the interleukin 2 (IL-2) receptor signaling specifically through STAT5 was critical for the development of Tregs by binding to the FoxP3 gene. In a follow-up study Farrar working with another collaborator proposed a two-step model for Treg development: a strong signal through the T-cell receptor (TCR) produces Treg progenitors with high expression of cell-surface IL-2 receptors; IL-2 signals then drive the conversion of the Treg progenitors into mature Tregs. The way a progenitor cell knows that its got a strong TCR signal is that it is linked to a series of cell-surface tumor necrosis factor receptor superfamily (TNFRSF) members that prime the cell to be sensitive to IL-2. The tighter the TNFRSF linkage and thus IL-2 sensitivity, the greater the likelihood of the progenitor cell becoming a Treg. Tregs are focused on high-affinity self-antigens like insulin and in that capacity help to prevent autoimmune reactions like diabetes.

A third focus of Farrar’s research, one that bridges the two described above, is cancer immunotherapy. His team is tracking how the immune system responds to tumor antigens in leukemia, specifically ALL with the BCR-ABL fusion gene. With the working hypothesis that the BCR-ABL fusion gene produces a peptide that the immune system does not recognize and could serve as a rejection antigen, Farrar’s laboratory set out to develop a tool to track the immune response to BCR-ABL. In this effort he collaborated with Marc Jenkins in Microbiology who has developed MHC class II tetramers. These tetramers allow tracking of T cells specific for one MHC peptide complex. By tetramerizing the BCR-ABL peptide, they found that there are a small number T cells in mice that can recognize the peptide encoded by the fusion of BCR to ABL.. Injecting leukemia cells into these mice produces a Treg expansion, which serves to suppress any immune response. Farrar and his colleagues are employing a vaccination strategy to see whether it is possible to boost the immune response and prolong survival in mice and ultimately in humans following chemotherapy.


  • Patent number: 5,463,023; Citation: Composition for Inhibition of Intracellular Transcription. Patent no. 5, 463,023. Issued to Robert D. Schreiber, Andrew C. Greenlund, and Michael A. Farrar on 10/31/95.
  • Patent number: 5,582,999; Citation: Methods for Inhibition of Intracellular Transcription Factor. Patent no. 5,582,999. Issued to Robert D. Schreiber, Andrew C. Greenlund, and Michael A. Farrar on 12/10/96.


  • Tracy SI, Venkatesh H, Hekim C, Heltemes Harris LM, Knutson TP, Bachanova V, Farrar MA. Combining nilotinib and PD-L1 blockade reverses CD4+ T-cell dysfunction and prevents relapse in acute B-cell leukemia. Blood. 2022 Mar 11.
  • Irey EA, Lassiter CM, Brady NJ, Chuntova P, Wang Y, Knutson TP, Henzler C, Chaffee TS, Vogel RI, Nelson AC, Farrar MA, Schwertfeger KL. JAK/STAT inhibition in macrophages promotes therapeutic resistance by inducing expression of protumorigenic factors. Proc Natl Acad Sci U S A. 2019 May 30. pii: 201816410. doi: 10.1073/pnas.1816410116. 
  • Liu B, Salgado OC, Singh S, Hippen KL, Maynard JC, Burlingame AL, Ball LE, Blazar BR, Farrar MA, Hogquist KA, Ruan HB. The lineage stability and suppressive program of regulatory T cells require protein O-GlcNAcylation. Nat Commun. 2019 Jan 21;10(1):354. doi: 10.1038/s41467-019-08300-3.
  • Owen DL, Mahmud SA, Vang KB, Kelly RM, Blazar BR, Smith KA, Farrar MA. Identification of Cellular Sources of IL-2 Needed for Regulatory T Cell Development and Homeostasis. J Immunol. 2018 Jun 15;200(12):3926-3933. doi: 10.4049/jimmunol.1800097. Epub 2018 May 4.
  • Casey D S Katerndahl, Lynn M Heltemes-Harris, Mark J L Willette, Christine M Henzler, Seth Frietze, Rendong Yang, Hilde Schjerven, Kevin A T Silverstein, Laura B Ramsey, Gregory Hubbard, Andrew D Wells, Roland P Kuiper, Blanca Scheijen, Frank N van Leeuwen, Markus Müschen, Steven M Kornblau, and Michael A Farrar (2017).   Antagonism of B cell enhancer networks by STAT5 drives leukemia and poor patient survival. Nature Immunology.  doi:10.1038/ni.3716
  • Luke S. Manlove, Jason M. Schenkel, Kezia R. Manlove, Kristen E. Pauken, Richard T. Williams, Vaiva Vezys, Michael A. Farrar.  Heterologous vaccination and checkpoint blockade synergize to induce antileukemia immunity. J Immunol. 2016 Jun 1;196(11):4793-804. doi: 10.4049/jimmunol.1600130. Epub 2016 Apr 25.
  • L.M. Heltemes-Harris, J.D. Larson, T.K. Starr, G.K. Hubbard, A.L. Sarver, D.A. Largaespada and M.A. Farrar. Sleeping Beauty Transposon screen identifies signaling modules that cooperate with STAT5 activation to induce B cell acute lymphoblastic leukemia. Oncogene, Oct 26. doi: 10.1038/onc.2015.405. [Epub ahead of print]
  • L.S. Manlove, K.E. Vrieze, K.E. Pauken, R.T. Williams, M.K. Jenkins, and M.A. Farrar. Adative immunity to leukemia is inhibited by crosreactive peripheral regulatory T cells. J. Immunol. 195: 4028-4037.
  • Mahmud SA, Manlove LS, Schmitz HM, Xing Y, Wang Y, Owen DL, Schenkel JM, Boomer JS, Green JM, Yagita H, Chi H, Hogquist KA, Farrar MA. Costimulation via the tumor-necrosis factor receptor superfamily couples TCR signal strength to the thymic differentiation of regulatory T cells. Nat Immunol. 2014 May;15(5):473-81. doi: 10.1038/ni.2849. Epub 2014 Mar 16
  • M.A. Burchill, J.J Moon, H.H. Chu, K.B. Vang, C-W.J. Lio, A.L. Vegoe, C-S. Hsieh, M.K. Jenkins, and M.A. Farrar. (2008). Linked T Cell Receptor and Cytokine Signaling Govern the Development of the Regulatory T cell repertoire. Immunity. 28: 112-121.
  • M.A. Burchill, J. Yang, C. Vogtenhuber, B.R. Blazar, and M.A. Farrar. (2007). Interleukin-2-Receptor-dependent STAT5 Activation is Required for the Development of Foxp3+ Regulatory T Cells. J. Immunol. 178: 262-270.
  • C.A. Goetz, I.R. Harmon, J.J. O’Neil, M.A. Burchill, and M.A. Farrar. STAT5 Activation Underlies Interleukin-7-dependent B Cell but not T Cell Development. J Immunol. Apr 15;172(8):4770-8, 2004.
  • L. Li, C.A. Goetz, C.D.S. Katerndahl, N. Sakaguchi and M.A. Farrar (2010). A Flt3 and Ras-dependent Pathway Primes B Cell Development by Inducing A State of IL7-responsiveness. J Immunol, 184: 1728-36.
  • K.B. Vang, J. Yang, A.J. Pagan, L. Li, J. Wang, J.M. Green, A.A. Beg and M.A. Farrar. (2010). Cutting edge: CD28 and c-Rel-Dependent Pathways Initiate Regulatory T Cell Development. J. Immunol. 184, 4074 -4077.
  • L. Heltemes Harris*, M Willette*, L.B. Ramsey*, Y.H. Qui, E.S. Neeley, N. Zhang, D.A. Thomas, T. Koeuth, E.C. Baechler, S.M. Kornblau, M.A. Farrar. 2011 Ebf1 or Pax5 haploinsufficiency synergizes with STAT5 activation to initiate acute lymphoblastic leukemia. The Journal of Experimental Medicine. 208: 1135-1149.
  • M.A. Farrar and L.M. Heltemes-Harris. (2011). Turning Transcription ON or OFF with STAT5:when more is less. Nat Immunol 12: 1139-1140.
  • J.H. Rowe, J.M. Ertelt, M.N. Aguilera, C.Y. Law, M.A. Farrar, S.S. Way. (2011). Expanded Foxp3+ regulatory T cells sustain pregnancy, but impair host defense exploited by prenatal bacterial pathogens. Cell Host & Microbe, 10: 54-64.