title: Pathogen-Specific T Cell Polyfunctionality Is a Correlate of T Cell Efficacy and Immune Protection.
abstract: BACKGROUND
  Understanding the factors that delineate the efficacy of T cell responses towards pathogens is crucial for our ability to develop potent therapies against infectious diseases. Multidimensional evaluation of T cell functionality at the single-cell level enables exhaustive analysis of combinatorial functional properties, hence polyfunctionality. We have recently invented an algorithm that quantifies polyfunctionality, the Polyfunctionality Index (Larsen et al. PLoS One 2012). Here we demonstrate that quantitative assessment of T cell polyfunctionality correlates with T cell efficacy measured as the capacity to kill target cells in vitro and control infection in vivo.
  
  
  METHODS
  We employed the polyfunctionality index on two datasets selected for their unique ability to evaluate the polyfunctional imprint on T cell efficacy. 1) HIV-specific CD8+ T cells and 2) Leishmania major-specific CD4+ T cells were analysed for their capacity to secrete multiple effector molecules, kill target cells and control infection. Briefly, employing the Polyfunctionality Index algorithm we determined the parameter estimates resulting in optimal correlation between T cell polyfunctionality and T cell efficacy.
  
  
  RESULTS
  T cell polyfunctionality is correlated with T cell efficacy measured as 1) target killing (r=0.807, P<0.0001) and 2) lesion size upon challenge with Leishmania major (r=-0.50, P=0.004). Contrary to an approach relying on the Polyfunctionality Index algorithm, quantitative evaluation of T cell polyfunctionality traditionally ignores the gradual contribution of more or less polyfunctional T cells. Indeed, comparing both approaches we show that optimal description of T cell efficacy is obtained when gradually integrating all levels of polyfunctionality in accordance with the Polyfunctionality Index.
  
  
  CONCLUSIONS
  Our study presents a generalizable methodology to objectively evaluate the impact of polyfunctionality on T cell efficacy. We show that T cell polyfunctionality is a superior correlate of T cell efficacy both in vitro and in vivo as compared with response size. Therefore, future immunotherapies should aim to increase T cell polyfunctionality.
authors.affiliation: Inserm UMR-S1136, Institut Pierre Louis d'Epidémiologie et de Santé Publique, Paris, France.
authors.forename: Anders
authors.initials: A
authors.lastname: Boyd
authors.affiliation: Inserm UMR-S1135, Centre d'Immunologie et des Maladies Infectieuses (CIMI-Paris), Paris, France.
authors.forename: Jorge R
authors.initials: JR
authors.lastname: Almeida
authors.affiliation: Vaccine Research Center (VRC), National Institute of Allergy and Infectious Diseases, National Institutes of Health (NIH), Bethesda, MD, United States of America.
authors.forename: Patricia A
authors.initials: PA
authors.lastname: Darrah
authors.affiliation: Inserm UMR-S1135, Centre d'Immunologie et des Maladies Infectieuses (CIMI-Paris), Paris, France.
authors.forename: Delphine
authors.initials: D
authors.lastname: Sauce
authors.affiliation: Vaccine Research Center (VRC), National Institute of Allergy and Infectious Diseases, National Institutes of Health (NIH), Bethesda, MD, United States of America.
authors.forename: Robert A
authors.initials: RA
authors.lastname: Seder
authors.affiliation: Inserm UMR-S1135, Centre d'Immunologie et des Maladies Infectieuses (CIMI-Paris), Paris, France.
authors.forename: Victor
authors.initials: V
authors.lastname: Appay
authors.affiliation: Inserm UMR-S1135, Centre d'Immunologie et des Maladies Infectieuses (CIMI-Paris), Paris, France; AP-HP, Groupement Hospitalier Pitié-Salpêtrière, Département d'Immunologie, Paris, France; Sorbonne Universités, UPMC Univ Paris 06, CR7, CIMI-Paris, Paris, France.
authors.forename: Guy
authors.initials: G
authors.lastname: Gorochov
authors.affiliation: Inserm UMR-S1135, Centre d'Immunologie et des Maladies Infectieuses (CIMI-Paris), Paris, France; AP-HP, Groupement Hospitalier Pitié-Salpêtrière, Département d'Immunologie, Paris, France; Sorbonne Universités, UPMC Univ Paris 06, CR7, CIMI-Paris, Paris, France.
authors.forename: Martin
authors.initials: M
authors.lastname: Larsen
mesh_terms: D000465:Algorithms; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology* / Q000469:parasitology / Q000473:pathology / Q000821:virology; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology* / Q000469:parasitology / Q000473:pathology / Q000821:virology; D002999:Clone Cells; D016207:Cytokines / Q000096:biosynthesis / Q000276:immunology; D003602:Cytotoxicity, Immunologic; D066264:Datasets as Topic; D015658:HIV Infections / Q000276:immunology* / Q000473:pathology / Q000821:virology; D015497:HIV-1 / Q000276:immunology; D006801:Humans; D007113:Immunity, Innate; D016130:Immunophenotyping; D018320:Leishmania major / Q000276:immunology; D016773:Leishmaniasis, Cutaneous / Q000276:immunology* / Q000469:parasitology / Q000473:pathology; D018448:Models, Immunological; D016176:T-Lymphocyte Subsets / Q000276:immunology* / Q000469:parasitology / Q000473:pathology / Q000821:virology
chemical_list: D016207:Cytokines