Peter Burrows, Ph.D.

We are interested in the development of B lymphocytes and their subsequent antigen-dependent differentiation into effector cells. Immunoglobulin (Ig) gene rearrangements, as well as a number of essential changes in gene expression, take place as cells progress through this differentiation pathway. Our laboratory has been using both cellular and molecular approaches to characterize precursors of human B lineage cells and to identify novel genes whose expression is developmentally regulated. One new subfamily of genes that we have identified encodes proteins with homology to the Fc receptors for immunoglobulins (FcR). The two members of this family, FCRLA and FCRLB differ from previously identified FcR and other FcR-like (FCRL) molecules in that they are intracellular proteins. We have recently shown that FCRLA is a resident endoplasmic reticulum protein that binds Ig in this organelle. In striking contrast to the conventional plasma membrane FcRs, FCRLA binds multiple isotypes of Ig, IgM, IgG, and IgA. We are currently testing the hypothesis that FCRLA is important in the initial metabolism of Ig in B cells and thus in normal immune system function. Our findings thus far suggest a novel role for this protein in Ig assembly or degradation. Defects in human FCRLA expression may thus lead to autoimmunity or immunodeficiency diseases.

Hui Hu, Ph.D.

One of the major research projects in the Hu laboratory is to study Tfh cell differentiation and germinal center (GC) responses. The humoral immune response is one of the two effector arms of the immune system. Studies have shown that CD4+ T follicular helper (Tfh) cells are essential for long-lived, high affinity antibody responses. Yet the complex regulation that determines the initial development of Tfh cells, their developmental progression in germinal centers, and their fates after an immune response dissolves, is still not fully understood. The Hu laboratory is interested in identifying novel pathways underlying the differentiation of Tfh cells in humoral responses and designing new strategies to manipulate humoral responses for treatment of infectious diseases and autoimmune disorders. Recently the Hu laboratory has discovered that transcription factor Foxp1 is a rate-limiting and essential negative regulator of Tfh cell differentiation, drastically affecting GC and antibody responses (Nat. Immunol. 2014).

The Hu laboratory is also working to find ways to activate T cells under immunosuppressive circumstances. Much of the understanding of molecular mechanisms regulating immune responses is centered on pathways and processes that promote cell activation, division and differentiation. The Hu laboratory has demonstrated that cell-intrinsic signaling pathways are required to maintain mature T cells in a quiescent state (Nat. Immunol. 2011). If these pathways are disrupted, resting T cells become aberrantly activated even in the absence of antigen challenge. The Hu laboratory is interested in identifying regulatory genes and pathways that actively restrain T cell activation, and defining the roles of such negative regulatory pathways in controlling T cell quiescence, effector responses, memory maintenance, and tumor immunology.

Louis B. Justement, Ph.D.

Ongoing studies in the laboratory focus on elucidation of molecular mechanisms that control the T-dependent as well as the T-independent humoral immune response.  Projects in the laboratory focus on a range of specific processes that relate to; 1) maintenance and function of the marginal zone in the spleen and responses to blood borne pathogens, 2) initiation and maintenance of the germinal center reaction following challenge with T-dependent antigens, 3) the role of CD19 in regulating the duration of the primary humoral response and the formation of memory, and 4) the role of the adaptor protein HSH2 in regulating immunoglobulin class switching and terminal differentiation in response to T-independent and T-dependent antigens. A common theme for all of the projects listed above is the analysis of intracellular signaling processes that promote B cell activation, survival and differentiation. The laboratory has a long-standing interest in structure/function analysis of co-receptors on B cells, including CD45 and CD22. More recently, the laboratory has become interested in determining the functional role of the B cell co-receptor CD19 in regulating the primary humoral response and the generation of memory B cells through the use of transgenic mouse lines that express CD19 with specific mutations in cytoplasmic tyrosine residues. Studies focused on an analysis of the molecular mechanisms by which the adaptor protein HSH2 regulates B cell class switching utilize mouse models in which HSH2 expression has been modulated in the B cell lineage. Studies have determined that this adaptor functions downstream of TNFR family members and modulates distal signaling events important for terminal B cell differentiation. Studies related to marginal zone and germinal center biology focus on the cross-talk between different receptor types in trans that promote proper cellular development and function and rely on a wide range of knockout and transgenic mouse lines. Additionally, studies are ongoing to characterize the expression and function of the TREM locus receptor TREM-Like Transcript 2 (TLT2).  TLT2 is expressed on cells that play a role in the innate and adaptive immune responses and has been shown to potentiate cellular responses to a range of agonists that signal via G protein-coupled receptors. Thus, TLT2 is thought to play a critical role in regulating immune cell migration and trafficking, as well as activation. Studies pertaining to TLT2 are focused on delineation of the molecular mechanisms by which TLT2-mediated signaling affects the host response to fungal and bacterial pathogens, as well as its role in mediating acute inflammation.

Janusz H. Kabarowski, Ph.D.

Dr. Kabarowski’s research program is focused on the study of lipids and lipoprotein metabolism in chronic inflammatory disease (notably atherosclerosis and autoimmune disease). Early work characterized the role of the G2A lipid receptor in atherosclerosis and lipoprotein metabolism, showing that pro-atherogenic effects of this receptor may be mediated through its modulatory influence on hepatic High-Density Lipoprotein (HDL) biogenesis. More recently, Dr. Kabarowski’s group described autoimmune-mediated effects on HDL metabolism in normolipidemic mouse models of Systemic Lupus Erythematosus (SLE) and currently a major effort of his laboratory is directed toward developing therapeutic approaches by which anti-inflammatory and immunosuppressive properties of HDL may be harnessed to improve major Lupus phenotypes and combat premature atherosclerosis, a major cause of morbidity and mortality in this and other rheumatic autoimmune diseases. Emphasis is placed on determining the mechanisms by which protective anti-inflammatory properties of HDL are subverted by chronic inflammation, understanding how this influences immunoregulatory processes involved in SLE and atherosclerosis, and establishing the therapeutic efficacy of HDL-targeted approaches such as HDL mimetic peptides in SLE and other autoimmune diseases.

Masa Kamata, Ph.D.

The major research foci of our laboratory are understanding a) how viruses or malignant cells establish and maintain prolonged infections or uncontrolled cell division, respectively, in patients under host immune pressure and b) how the host immune system can be mobilized to fight infection or cancer. To this end, we have worked to establish effective strategies using humanized mouse and non-human primate models; our aim is to develop a treatment capable of achieving a state wherein the host immune system decreases levels of virus or cancer in patients to the point where further treatment is not necessary. Our recent efforts using immunotherapeutic strategies have provided potential tools for controlling HIV-1 load as well as aggressive cancers that metastasize to the brain. These studies provide fundamental insight into the basis of host-virus and host- malignant cell interactions and ultimately identify clinically relevant therapeutic targets to augment immune responses and restore antiviral or anticancer immunity in patients.

John F. Kearney, Ph.D.

The overall research plans of the Kearney laboratory are aimed at discovering fundamental cellular and molecular mechanisms involved in the development of T and B lymphocytes.  Particular attention is focused on the factors involved in the establishment of a diverse B cell repertoire and the identification of novel B cell subsets and B cell progenitors. This basic research is then applied to immune responses to the pathogens and opportunistic pathogens (Bacillus anthracis, Streptococcus pneumoniae, groups A and B streptococci, Enterobacter cloacae, Aspergillus fumigatus) thus leading to studies on mechanisms of disease in mouse models.

A major portion of the Kearney laboratory research addresses the “hygiene hypothesis” that links the increase in autoimmune and allergic phenomena including Type 1 diabetes and allergic asthma in humans to excessively sanitary conditions provided to our children early in life. These are significant public health problems worldwide, associated with an alarming decrease in the age of onset. A particular focus is on the role of antibodies to these organisms with the potential to dampen allergic and autoimmune diseases.

The objective of our work on autoimmune diabetes is based on the observations that (i) childhood infection with Group A strepococci that causes Scarlet fever has a negative impact on T1D development in humans and (ii) a similar effect is observed in rodent models. Antibodies are important in fighting infections but multiple studies now show that certain antibodies have housekeeping functions, in that they can clean up and dispose of dead or dying cells in our body. Our preliminary studies suggest that this novel approach will be effective in preventing the development of T1D by inducing long-term antibody production to self-antigens in beta islet cells without interfering with other immune functions. Our idea is that these antibodies will divert autoantigens into pathways that block or dampen the production of T lymphocytes with the potential to destroy insuIin-producing beta islet cells in the pancreas. Our goal is to develop a strategy that will provide a possible therapeutic or vaccination option for treatment or prevention of T1D. Antigen-based therapies to induce T cell tolerance use a single antigen whereas our approach has the potential to dampen autoimmunity against known or ignored determinants of beta cell secretory granules, and prevent spreading of anti-islet cell activity and inhibit late stage T1D.

Asthma is a potentially life threatening chronic respiratory disease, which is an increasingly significant public health problem worldwide. In the United States 16.4 million non-institutionalized adults and 7.0 million children currently have asthma, accounting for 7.3% and 9.4% of these total populations, respectively. The “hygiene hypothesis” links the increasing allergic airway diseases to lack of appropriate microbial exposure early in life. A single neonatal immunization of mice with a Group A streptococcal vaccine induces antibodies that are sustained well into adulthood and protect against airway allergic responses. Base on these findings we are investigating new therapeutic or vaccination options in mouse models of allergic airways disease for the prevention/treatment of allergic asthma.

Fungal infections involving opportunistic pathogens have increased dramatically in the last 20 yrs. due mainly to increased numbers of HIV patients, and severe immunosuppressive regimens involved in a variety of therapies such as bone marrow transplants and chemotherapy. The lack of effective vaccines and the emergence of strains resistant to effective anti-fungal agents have compounded the significance of this health problem that has a very high morbidity. We have shown that targeting antibodies to shared components of bacterial and fungal species elicit protective antibody responses to fungal infections in mice. Our ongoing studies on anti-fungal immunity revolve around identification of protective antibody to novel vaccine targets on Candida albicans and Aspergillus fumigatus.

Rodney King, Ph.D.

Dr. King has a long standing interest in B cell biology, specifically the factors that influence the production of their principle effector molecules, antibodies, and the role of these molecules in health and disease. More recently, he has focused on the analysis of glycan-specific B cell repertoire formation and the development of methodologies to facilitate the expression of recombinant antibody derived from the antigen receptor genes of single-sorted B cells. His current focus is on visualizing effects of environmental influences and commensal organisms on natural repertoire development in mice and humans and utilizing the constituents of these highly conserved glycan-specific repertoires to develop diagnostic and therapeutic reagents.

Christopher A. Klug, Ph.D.

Our laboratory has had a longstanding interest in understanding the genetic control of hematopoietic stem cell (HSC) differentiation into the earliest committed lymphoid cells in the bone marrow. This process is mediated by a number of factors including transcription factors and growth factor signaling pathways that both promote lineage specification as well as repress differentiation into alternative blood cell fates. Differentiation of HSC is also coupled with maintenance of the stem cell state in a process called self-renewal, which effectively maintains homeostasis within the hematopoietic system throughout life. Some of our ongoing work has focused on the characterization of murine and human mesenchymal stem cells (MSC), which form part of the HSC niche, for their ability to promote HSC self-renewal. This work has implications for expansion of HSC in vitro and for promotion of graft facilitation during bone marrow transplantation.

Beatriz León Ruiz, Ph.D.

Her current research objectives are directed toward understanding T helper type 2 (Th2)-driven immune responses. The Th2 immune response is critical in the host defense against parasitic infections, but it is also responsible for the pathogenesis of allergic disorders, such asthma. Dendritic cells (DCs) are essential in coordinating the fate decisions of naive CD4+ T cells toward distinct T helper cell subsets. Specifically, DC activation status plays a critical role in T helper cell polarization, including Th2 cell differentiation. However, it has been difficult to address the precise molecular mechanisms of Th2 induction. The lab has focused in the studying of the functional specialization of DCs for the induction of Th2 responses against allergens.

One of Dr. León lab’s major projects seeks to understand allergic asthma during infancy. Infants are three to four times more prone to develop allergies than adults. Therefore, emphasis is placed on understanding the different molecular mechanisms involved in the activation and Th2 cell polarization of allergen-specific CD4+ T cells by infant and adult DC. In a second project, the lab evaluates the mechanisms determining the commitment and plasticity of memory follicular helper CD4 T cells (Tfh) cells and their role in allergy. Finally, the lab also studies how maternal asthma affects asthma risk in offspring. Maternal asthma significantly increases the risk of asthma in offspring, but the mechanisms remain poorly defined. Using mouse models, the lab is investigating maternal factors that modify the DC activation status in the offspring and therefore their CD4+ T cell polarizing capacity. The broad, long term goals of her research program are to develop effective therapies for the treatment of Th2-mediated diseases such as allergic disease.

Frances Lund, Ph.D.

The overarching research objective of the Lund laboratory is to identify the key players that suppress or exacerbate mucosal immune responses with the long-term goal of developing therapeutics to treat immunopathology associated with chronic infectious, allergic and autoimmune disease. To evaluate inflammation and cellular immune responses in vivo, we utilize different strains of mice that have genetically altered immune systems. In particular, we focus on evaluating mice that have alterations in the B lymphocyte compartment. We expose these mice to pathogens, allergens or autoantigens and then study the ensuing immune responses in lymphoid organs and in mucosal tissues like the lung and gut. We study immune responses in mice that spontaneously develop autoimmune diseases like Systemic Lupus Erythematosus (SLE), Rheumatoid Arthritis (RA) or Type 1 Diabetes (T1D).  We also examine inflammatory and immune responses in mice exposed to common allergens like house dust mite or infected with viral (influenza, RSV), bacterial (Streptococcus pneumoniae, Listeria monocytogenes), fungal (Pneumocystis carinii) or parasitic (Heligmosomoides polygyrus) pathogens. Finally, we expose mice to toxins like cigarette smoke and DNA-damaging chemotherapeutics and monitor chronic inflammation and tissue damage in sites such as the lung.

Jiri Mestecky, M.D., Ph.D.

Our group has been involved for an extended time period in the studies of various aspects of mucosal immunology such as the polypeptide chain and glycan structures of secretory IgA antibodies, including the independent discovery of J chain. In parallel, cellular aspects of IgA biosynthesis, catabolism, and selective transepithelial transport have been investigated. We have demonstrated the cellular and tissue origins of various molecular forms of IgA (monomeric/polymeric of IgA1 and IgA2 subclasses)and determined tissue sites, cell types, and receptors involved in IgA binding and catabolism using various animal models and isolated cells. In collaboration with other members of the mucosal immunology group we studied the induction of humoral and cellular immune responses in mucosal sections and tissues and we provided direct evidence for the existence of the common mucosal immune system in humans. Various mucosal immunization routes, antigen delivery systems and adjuvants have been compared with respect to the magnitude, duration, and quality of immune responses induced at desired mucosal sites.

More recent studies have been focused on the impact and immune response induced by HIV infection or immunization with experimental vaccines. In parallel, studies of molecular defects and regulation of glycosylation of IgA1 isolated from sera of patients with the most common glomerulonephritis in the world – IgA nephropathy – led to the discovery of the molecular basis of this disease and characterization of nephritogenic immune complexes.

Suzanne Michalek, Ph.D.

We are interested in the mucosal and innate immune systems; the development of mucosal vaccines against microbial pathogens; cellular mechanisms engaged following microbial-host interaction, e.g., signaling pathways activated, that could lead to the development of immunotherapeutics.

Jan Novak, Ph.D.

Dr. Novak’s research interests in Immunology include glycoimmunobiology and glycoimmunopathology as they relate to structure and function of antibodies and other glycoproteins in health and disease and possible interventional approaches for treatment of diseases. Major topics are related to renal diseases and autoimmune diseases (IgA nephropathy and other chronic diseases of the kidney), cancer, and mucosal infections, including sexually transmitted diseases, such as those caused by HIV.

Carlos J Orihuela, Ph.D.

The Orihuela laboratory examines the host-pathogen interactions that occur during invasive pneumococcal disease. This includes dissecting at a molecular level how Streptococcus pneumoniae virulence determinants interact with the host, how the host cell responds to infection at the cell signaling level, and how these interactions change with advanced age. Currently the Orihuela laboratory is exploring the new observation that S. pneumoniae invades the heart and causes long-lasting cardiac damage during pneumonia. Specific topics that are being investigated include necroptosis, a pro-inflammatory cell death pathway, involved in pneumolysin-mediated killing of monocytes and cardiomyocytes, how inflamm-aging enhances permissiveness for bacterial infection through upregulation of homeostatic suppressors meant to keep sterile inflammation under control, and the host response to different bacterial phenotypes during its growth within an infected heart.

Hubert Tse, Ph.D.

My research program seeks to define and prevent immune-mediated effector mechanisms involved in the destruction of insulin-producing pancreatic beta-cells in autoimmune Type 1 diabetes (T1D). An overarching theme in our research is to determine the role of oxidative stress and the generation of reactive oxygen species (ROS) as damaging and signaling molecules in autoimmune and pro-inflammatory-mediated diseases. To corroborate the importance of ROS-dependent signaling in T1D, a dominant negative p47phox (Ncf1m1J) mutation of the NADPH oxidase complex was introgressed into the Non-Obese Diabetic (NOD) mouse, a spontaneous mouse model for studying Type 1 diabetes. NOD.Ncf1m1J mice are impaired in ROS synthesis and highly resistant to spontaneous diabetes and adoptive transfer of diabetes with diabetogenic T cells. We have shown that ROS synthesis is essential for maturing both the innate and adaptive immune arms including macrophage, CD4+ and CD8+ T cell responses involved in pancreatic beta-cell destruction. Pro-inflammatory macrophages constitute the first wave of immune cells to infiltrate pancreatic islets, initiate beta-cell destruction, and present antigen to naïve diabetogenic T cells. Currently, we seek to understand the synergy of oxidative stress on the activation of macrophages to diabetogenic viral triggers (Coxsackieviruses, Encephalomyocarditis virus) and the importance of cell surface thiols and thiol-dependent signaling pathways on autoreactive mouse and human T cell responses. Finally, we are also interested in determining the efficacy of islet encapsulation to delay graft rejection, preserve islet function, and maintain euglycemia in allo- and xenotransplantation T1D mouse models.

Eric Ubil, Ph.D.

The Problem:  Existing Immunotherapies Have Limited Efficacy in Many Tumors. Since the discovery thta tumors act on adaptive immune checkpoints to limit the immune response, a number of targeted therapies have been developed; some of which have become widely used in the clinic. Targeted therapies directed to CTLA4 (ipilumamab) and PD-1 ((pembrolizumab and nivolumab) or PD-L1 (atezolimumab) have led to increased survival. In some cases, these treatments lead to durable responses with limited toxicity. Unfortunately, across cancer types, the majority of patients do not respond to treatment. As an example, depending on the study, only 25-30% of metastatic melanoma patients respond to targeted immunotherapy. For prostate, breast and colon cancer, response rates are substantially lower. Even among responders, many later relapse, presumably because tumors evolve to acquire resistance to the target modality.

In light of clinical successes, limited as they may be, many recognize the promise of targeted immunotherapy to improve clinical outcomes. Continued research has led to the discovery of a number of novel immune checkpoints and development of targeted therapies to each. Several clinical studies also seek to combine novel targeted therapies with current clinical treatments to improve survival.

Our Research: Discovering New Ways to Target an Innate Immune Checkpoint.
Our laboratory studies how a tumor-secreted protein (Protein S, Pros1) is utilized by tumors during cancer progression to reduce the pro-inflammatory gene expression of macrophages.  In a previous publication (Ubil et al. JCI, 2018), we showed that tumors upregulate their expression/secretion of Pros1 when they recognize local immune activation (IFNγ).  Presumably this is a defense mechanism, much like expression of PD-L1 (which is also upregulated in the presence of IFNγ), to effectively reduce local immune activation and create a tumor-permissive environment allowing cancer growth and metastasis.

We have shown that tumor-secreted Pros1 acts as a ligand for macrophage receptor tyrosine kinases Mer and Tyro3.  Upon binding of Pros1 to Mer, p38α (a key activator of pro-inflammatory gene expression) is sequestered to Mer, preventing nuclear translocation and c-Jun mediated transcription initiation.  The sequestration of p38α is facilitated by a phosphatase called PTP1b, which effectively forms a link between Mer and p38α.

In the absence of PTP1b (genetic deletion in macrophages) or through pharmacological inhibition, association of macrophage Mer and p38α is lost, even in the presence of Pros1, and pro-inflammatory gene expression is restored in tissue culture models.

Project 1: Can PTP1b inhibition be used as a mono- or combination therapy to improve outcomes in murine cancer models?

We are currently investigating whether PTP1b inhibition affects tumor immune infiltrate and, if so, whether that leads to reductions in tumor growth and progression.  We are utilizing a variety of murine models, and exploring whether outcomes of standard of care therapies can be improved with the addition of pharmacological PTP1b inhibition.

Project 2: What is the role of Mer kinase activity in immune suppression?

Conflicting reports, dating back almost 20 years, suggest alternative roles for Mer kinase activity in immune suppression.  Mer kinase inhibitors have been developed as a therapeutic for human cancer and are currently in Phase I clinical trials.  Our data, and that of others, suggest Mer kinase function may play a limited role in the tumor immune suppressive context.  We know that Mer has kinase-independent functions but, to date, they have not been fully elucidated.  We are currently working to better understand the mechanisms by which Mer inhibits the innate immune response.

Project 3: We know that several tumors express Pros1 at comparable levels but the immune suppression induces varies.  Why?

Measurements of secreted Pros1 among different tumor types is surprisingly consistent.  However, when their ability to suppress the macrophage pro-inflammatory response is measured, there is a spectrum of suppressive activity.  The lab is investigating whether genetic or alternative factors play a role, making some tumors more suppressive than others.  The hope is that if we can identify which patient tumors are most suppressive by this mechanism, we can more effectively target patients that will benefit the most to achieve better clinical outcomes.

Mark R. Walter, Ph.D.

Role of Interferons and other cytokines in Lupus:  The type I interferon family (IFNs) consists of 15 different molecules that have diverse functions such as activating cells to control viral infections.  However, the IFNs also play a pathogenic role in an autoimmune disease called systemic lupus erythematosus (SLE).  The IFNs have been implicated in the initiation and worsening of the disease, most notably in kidney damage (lupus nephritis).  The Walter lab is designing molecular tools to measure IFN levels in the blood and kidneys of lupus patients.  The project is expanding to evaluate how other cytokine pathways intersect with the IFNs in disease progression.  The results of these studies may be used to monitor disease and/or choose the appropriate therapy to improve patient health.  This is a collaborative project between clinicians and biochemists motivated to understand how to prevent and/or manage the devastating impact of lupus on people’s lives. 

Design of novel vaccines against human cytomegalovirus (HCMV):  Current viral vaccines elicit antibodies to viral proteins that prevent or limit entry of virus into cells of their host.  To date, this strategy has not been successful in a number of viruses, including HCMV, that directly target immune cell signaling pathways to evade host immune responses.  HCMV infection can cause severe hearing loss, mental disabilities, and even death in a developing fetus (For more information see this link).  Currently there is no vaccine for HCMV.  To address this problem, we are using our expertise in cytokine structural biology to design novel antigens that target virally produced cytokines.  To date, these antigens show efficacy in animal models of HCMV.   Further testing of this strategy and evaluating molecules for possible clinical trials are now underway.  See

1.  Logsdon et al.  Design and Analysis of Rhesus Cytomegalovirus IL-10 Mutants as a Model for Novel Vaccines against Human Cytomegalovirus. PLoS One. 6 (2011).

2.  Eberhardt et al. Host Immune Responses to a Viral Immune Modulating Protein: Immunogenicity of Viral Interleukin-10 in Rhesus Cytomegalovirus-Infected Rhesus Macaques. PLoSOne 7 (2012).  

Allan J. Zajac, Ph.D

I love studying cell-mediated immune responses to infections. My research program is centered upon understanding why robust and highly effective immune responses are induced by certain viral infections and vaccinations and why and how they become corrupted during persistent infections, compromising viral control. Our studies have shown that virus-specific CD8 T cells succumb to exhaustion during persistent infections, and have highlighted a vital role for CD4 T cells in supporting CD8 T cell responses. We also discovered that the CD4 T cell-derived cytokine, IL-21, is essential for sustaining cell-mediated immunity in chronically infected hosts. More recently, we demonstrated that adhesion molecule interactions influence the balance of effector and memory phenotype cells, and also regulate the deletion of virus-specific CD8 T cells during chronic infections. As our projects have advanced a common immunological theme that has emerged is the central role of cytokines, as both intrinsic regulators and predictors of the outcome of the CD8 T cell response, and also as extrinsic factors that provoke and direct their development. Consequently, our interests have evolved towards analytically deconvoluting the functional complexity of CD8 T cell responses, with a major goal of understanding how the formation of discrete cytokine-producing subsets is controlled and how they contribute to the clearance of infections and tumors. These studies are helping to define how CD8 T cell functional disparities translate to qualitative and quantitative differences in the ensuing response, forecast fate decisions, and dictate protective efficacy.