James Stafford

Professor, Faculty of Science - Biological Sciences
Associate Chair (Graduate)
Associate Chair (Graduate), Faculty of Science - Biological Sciences


Professor, Faculty of Science - Biological Sciences
(780) 492-9258
CW-330 & CW-332 Bio Science - Centre Wing
11355 - Saskatchewan Drive
Edmonton AB
T6G 2E9

Associate Chair (Graduate)

Associate Chair (Graduate), Faculty of Science - Biological Sciences




Medical Laboratory Sciences, University of Alberta


Physiology and Cell Biology, Department of Biological Sciences, University of Alberta


University of Mississippi Medical Center, Jackson, MS, USA

Innate immunity is an essential component of the vertebrate antimicrobial defense system. This protection depends on the integrated activity of highly specialized immune cell-types that are responsible for the recognition and clearance of pathogens. One of these fundamental innate cell responses is called phagocytosis (immune cell eating), which involves dynamic remodeling of the plasma membrane during the capture and ingestion of extracellular material.

Phagocytosis is an ancient cellular process that was established for simple nutrient acquisition in primitive unicellular organisms, but has since evolved into a complex immune defense response utilized by all multicellular animals. Cells that perform phagocytosis are collectively known as phagocytes and their unique ability to engulf large (>0.5 µm) particulate targets is dependent on the expression of distinct immune receptor-types. The best-characterized phagocytic receptors include the mammalian complement receptors (CR), dectin-1, and members of the Fc receptor (FcR) family. Studies from these model immune proteins have identified phagocytosis as a temporally coordinated process that tightly regulates plasma membrane remodelling events during the capture, ingestion, and eventual destruction of microbes. Each phagocytic receptor-type relays extracellular target binding into dynamic filamentous (F)-actin-mediated remodelling of the plasma membrane through specific intracellular signaling events. Despite the recognized diversity in receptor-mediated phagocytic signaling, phagocytic pathways generally require tyrosine kinase activity, localized phospholipid metabolism, activation of Rho-family small GTPases, and the engagement of various actin nucleation and regulatory factors. Importantly, the molecular components that regulate phagocytosis are also vital for many other biological responses, including: cell adhesion and migration, wound repair, and the clearance of debris from tissues. As a result, phagocytosis is not only an excellent model for studying receptor-mediated signaling events in immunity, but also for investigating fundamental aspects of the regulatory machinery involved in the control of plasma membrane dynamics.

Despite an in-depth understanding of phagocytosis in mammals, very little is currently known in basal vertebrates. Interestingly, there are more than 25,000 known species of teleost fishes that thrive in diverse aquatic ecosystems populated with numerous bacterial, parasitic, and viral pathogens. Fish exhibit robust innate immune mechanisms that deal with this continuous assault, including phagocytosis, but how these responses are specifically regulated in ectothermic vertebrates is largely unknown. Genome sequencing has recently revealed a vast inventory of fish immune genes, including a large number and diversity of immune receptor-types. However, the functional roles played by these teleost receptor proteins remains to be determined. In an effort to understand conserved and divergent aspects of innate immune processes across vertebrates, my research has focused on the characterization of channel catfish (Ictalurus punctatus) leukocyte immune-type receptors (IpLITRs). These efforts have recently uncovered new details regarding teleost immunoregulatory-mediated signaling pathways and their functional capabilities.

My ongoing research program uses IpLITR proteins as an innate receptor model system to study immunregulatory receptor signaling events in vertebrates. Please see Featured Publications and the Stafford LAB page for further details about our research.


A novel family of diversified immunoregulatory receptors in teleosts is homologous to both mammalian Fc receptors and molecules encoded within the leukocyte receptor complex
Author(s): Stafford JL, Bengten E, Du Pasquier L, McIntosh RD, Quiniou SM, Clem LW, Miller NW
Publication: Immunogentics
Volume: 58
Issue: 9
Page Numbers: 758-773
External Link: http://link.springer.com/article/10.1007/s00251-006-0134-1
Cell surface expression of channel catfish leukocyte immune-type receptors (IpLITRs) and recruitment of both Src homology 2 domain-containing protein tyrosine phosphatase (SHP)-1 and SHP-2
Author(s): Montgomery BCS, Mewes J, Davidson C, Burshtyn DN, Stafford JL
Publication: Developmental & Comparative Immunology
Volume: 33
Issue: 4
Page Numbers: 570-582
External Link: http://www.sciencedirect.com/science/article/pii/S0145305X08002334
Channel catfish leukocyte immune-type receptor mediated inhibition of cellular cytotoxicity is facilitated by SHP-1-dependent and -independent mechanisms
Author(s): Montgomery BC, Cortes HD, Burshtyn DN, Stafford JL
Publication: Developmental & Comparative Immunology
Volume: 37
Issue: 1
Page Numbers: 151-163
External Link: http://www.sciencedirect.com/science/article/pii/S0145305X11002345
Channel catfish leukocyte immune-type receptors contain a putative MHC class I binding site
Author(s): Stafford JL, Bengten E, Du Pasquier L, Miller NW, Wilson M
Publication: Immunogentics
Volume: 59
Issue: 1
Page Numbers: 77-91
External Link: http://link.springer.com/article/10.1007/s00251-006-0169-3
Connected component masking accurately identifies the ratio of phagocytosed and cell-bound particles in individual cells by imaging flow cytometry
Author(s): Fei C, Lillico DME, Hall B, Rieger AM, Stafford JL
Publication: Cytometry Part A
External Link: http://onlinelibrary.wiley.com/doi/10.1002/cyto.a.23050/full
Examination of the stimulatory signaling potential of a channel catfish leukocyte immune-type receptor and associated adaptor
Author(s): Cortes HD, Montgomery BC, Verheijen K, Garcia-Garcia E, Stafford JL
Publication: Developmental & Comparative Immunology
Volume: 36
Issue: 1
Page Numbers: 62-73
External Link: http://www.sciencedirect.com/science/article/pii/S0145305X11001704
Identification and Characterization of a FcR Homolog in an Ectothermic Vertebrate, the Channel Catfish (Ictalurus punctatus)
Author(s): Stafford JL, Wilson M, Nayak D, Quiniou SM, Clem LW, Miller NW, Bengten M
Publication: The Journal of Immunology
Volume: 177
Issue: 4
Page Numbers: 2505-2517
External Link: http://www.jimmunol.org/content/177/4/2505.full
Imaging flow cytometry and GST pulldown assays provide new insights into channel catfish leukocyte immune-type receptor-mediated phagocytic pathways
Author(s): Zwozdesky MA, Fei C, Lillico DME, Stafford JL
Publication: Developmental & Comparative Immunology
Volume: 67
Page Numbers: 126-138
External Link: http://www.sciencedirect.com/science/article/pii/S0145305X16303743
Induction of Phagocytosis and Intracellular Signaling by an Inhibitory Channel Catfish Leukocyte Immune-Type Receptor: Evidence for Immunoregulatory Receptor Functional Plasticity in Teleosts
Author(s): Cortes HD, Lillico DME, Zwozdesky MA, Pemberton JG, O'Brien A, Montgomery BCS, Wiersma, L, Chang JP, Stafford JL
Publication: Journal of Innate Immunity
Volume: 6
Page Numbers: 435-455
External Link: http://www.karger.com/Article/Abstract/356963
Biochemical and Functional Insights into the Integrated Regulation of Innate Immune Cell Responses by Teleost Leukocyte Immune-Type Receptors
Author(s): Fei C, Pemberton JG, Lillico DME, Zwozdesky MA, Stafford JL
Publication: Biology
Volume: 5
Issue: 1
Page Numbers: 13
External Link: http://www.mdpi.com/2079-7737/5/1/13/htm
Teleost IgSF immunoregulatory receptors
Author(s): Montgomery BCS, Cortes HD, Mewes-Ares J, Verheijen K, Stafford JL
Publication: Developmental & Comparative Immunology
Volume: 35
Issue: 12
Page Numbers: 1223-1237
External Link: http://www.sciencedirect.com/science/article/pii/S0145305X1100070X
Stimulatory catfish leukocyte immune-type receptors (IpLITRs) demonstrate a unique ability to associate with adaptor signaling proteins and participate in the formation of homo- and heterodimers
Author(s): Mewes J, Verheijen J, Montgomery BCS, Stafford JL
Publication: Molecular Immunology
Volume: 47
Issue: 2
Page Numbers: 318-331
External Link: http://www.sciencedirect.com/science/article/pii/S0161589009007160
Teleost leukocyte immune-type receptors activate distinct phagocytic modes for target acquisition and engulfment
Author(s): Lillico DME, Zwozdesky MA, Pemberton JG, Deutscher JM, Jones LO, Chang JP, Stafford JL
Publication: Journal of Leukocyte Biology
Volume: 98
Issue: 2
Page Numbers: 235-248
External Link: http://www.jleukbio.org/content/98/2/235.full
Trypsin differentially modulates the surface expression and function of channel catfish leukocyte immune-type receptors
Author(s): Lillico DME, Pemberton JG, Stafford JL
Publication: Developmental & Comparative Immunology
Volume: 65
Page Numbers: 231-244
External Link: http://www.sciencedirect.com/science/article/pii/S0145305X16302312