title: Defective Leukocyte Adhesion and Chemotaxis Contributes to Combined Immunodeficiency in Humans with Autosomal Recessive MST1 Deficiency.
abstract: OBJECTIVE
  To investigate the clinical and functional aspects of MST1 (STK4) deficiency in a profoundly CD4-lymphopenic kindred with a novel homozygous nonsense mutation in STK4. Although recent studies have described the cellular effects of murine Mst1 deficiency, the phenotype of MST1-deficient human lymphocytes has yet to be fully explored. Patient lymphocytes were therefore investigated in the context of current knowledge of murine Mst1 deficiency.
  
  
  METHODS
  Genetic etiology was identified by whole exome sequencing of genomic DNA from two siblings, combined with linkage analysis in the wider family. MST1 protein expression was assessed by immunoblotting. The ability of patient lymphocytes to adhere to ICAM-1 under flow conditions was measured, and transwell assays were used to assess chemotaxis. Chemokine receptor expression was examined by flow cytometry and receptor signalling by immunoblotting.
  
  
  RESULTS
  A homozygous nonsense mutation in STK4 (c.442C > T, p.Arg148Stop) was found in the patients, leading to a lack of MST1 protein expression. Patient leukocytes exhibited deficient chemotaxis after stimulation with CXCL11, despite preserved expression of CXCR3. Patient lymphocytes were also unable to bind effectively to immobilised ICAM-1 under flow conditions, in keeping with a failure to develop high affinity binding.
  
  
  CONCLUSIONS
  The observed abnormalities of adhesion and migration imply a profound trafficking defect among human MST1-deficient lymphocytes. By analogy with murine Mst1 deficiency and other defects of leucocyte trafficking, this is likely to contribute to immunodeficiency by impairing key aspects of T-cell development and function such as positive selection in the thymus, thymic egress and immune synapse formation in the periphery.
authors.affiliation: Institute for Cellular Medicine, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK.
authors.forename: Tarana Singh
authors.initials: TS
authors.lastname: Dang
authors.affiliation: Institute for Cellular Medicine, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK.
authors.forename: Joseph D P
authors.initials: JD
authors.lastname: Willet
authors.affiliation: Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, UK.
authors.forename: Helen R
authors.initials: HR
authors.lastname: Griffin
authors.affiliation: School of Clinical and Experimental Medicine, University of Birmingham, Birmingham, UK.
authors.forename: Neil V
authors.initials: NV
authors.lastname: Morgan
authors.affiliation: Institute for Cellular Medicine, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK.
authors.forename: Graeme
authors.initials: G
authors.lastname: O'Boyle
authors.affiliation: Department of Paediatric Allergy & Immunology, Royal Manchester Children's Hospital, University of Manchester, Manchester, UK.
authors.forename: Peter D
authors.initials: PD
authors.lastname: Arkwright
authors.affiliation: Department of Paediatric Allergy & Immunology, Royal Manchester Children's Hospital, University of Manchester, Manchester, UK.
authors.forename: Stephen M
authors.initials: SM
authors.lastname: Hughes
authors.affiliation: Institute for Cellular Medicine, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK.|Great North Children's Hospital, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne, UK.
authors.forename: Mario
authors.initials: M
authors.lastname: Abinun
authors.affiliation: School of Clinical and Experimental Medicine, University of Birmingham, Birmingham, UK.
authors.forename: Louise J
authors.initials: LJ
authors.lastname: Tee
authors.affiliation: Blood Sciences Flow Cytometry Laboratory, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne, UK.
authors.forename: Dawn
authors.initials: D
authors.lastname: Barge
authors.affiliation: Institute for Cellular Medicine, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK.
authors.forename: Karin R
authors.initials: KR
authors.lastname: Engelhardt
authors.affiliation: Great North Children's Hospital, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne, UK.
authors.forename: Michael
authors.initials: M
authors.lastname: Jackson
authors.affiliation: Institute for Cellular Medicine, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK.|Great North Children's Hospital, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne, UK.
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Cant
authors.affiliation: School of Clinical and Experimental Medicine, University of Birmingham, Birmingham, UK.|Department of Medical Genetics, University of Cambridge, Cambridge, UK.
authors.forename: Eamonn R
authors.initials: ER
authors.lastname: Maher
authors.affiliation: Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, UK.
authors.forename: Mauro Santibanez
authors.initials: MS
authors.lastname: Koref
authors.affiliation: Institute for Cellular Medicine, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK.
authors.forename: Louise N
authors.initials: LN
authors.lastname: Reynard
authors.affiliation: Institute for Cellular Medicine, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK.
authors.forename: Simi
authors.initials: S
authors.lastname: Ali
authors.affiliation: Institute for Cellular Medicine, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK. sophie.hambleton@newcastle.ac.uk.|Great North Children's Hospital, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne, UK. sophie.hambleton@newcastle.ac.uk.
authors.forename: Sophie
authors.initials: S
authors.lastname: Hambleton
mesh_terms: D002448:Cell Adhesion / Q000235:genetics*; D002634:Chemotaxis, Leukocyte / Q000235:genetics*; D002675:Child, Preschool; D005260:Female; D005808:Genes, Recessive; D006801:Humans; D007153:Immunologic Deficiency Syndromes / Q000175:diagnosis* / Q000235:genetics* / Q000378:metabolism; D016130:Immunophenotyping; D018799:Intercellular Adhesion Molecule-1 / Q000378:metabolism; D047908:Intracellular Signaling Peptides and Proteins; D008214:Lymphocytes / Q000276:immunology / Q000378:metabolism; D010375:Pedigree; D010641:Phenotype; D017346:Protein Serine-Threonine Kinases / Q000172:deficiency*; D035781:Siblings; D000099317:Hippo Kinases
chemical_list: D018799:Intercellular Adhesion Molecule-1; D047908:Intracellular Signaling Peptides and Proteins; D017346:Protein Serine-Threonine Kinases; C095566:STK4 protein, human; D000099317:Hippo Kinases
keywords: CD4 lymphopenia; Combined immunodeficiency; MST1; STK4; chemotaxis; lymphocyte adhesion