Defective Leukocyte Adhesion and Chemotaxis Contributes to Combined Immunodeficiency in Humans with Autosomal Recessive MST1 Deficiency

Tarana Singh Dang, Joseph D.P. Willet, Helen R. Griffin, Neil V. Morgan, Graeme O’Boyle, Peter D. Arkwright, Stephen M. Hughes, Mario Abinun, Louise J. Tee, Dawn Barge, Karin R. Engelhardt, Michael Jackson, Andrew J. Cant, Eamonn R. Maher, Mauro Santibanez Koref, Louise N. Reynard, Simi Ali, Sophie Hambleton*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Purpose: 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. Conclusion: 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.

Original languageEnglish
Pages (from-to)117-122
Number of pages6
JournalJournal of Clinical Immunology
Volume36
Issue number2
Early online date22 Jan 2016
DOIs
Publication statusPublished - 1 Feb 2016

Keywords

  • CD4 lymphopenia
  • chemotaxis
  • Combined immunodeficiency
  • lymphocyte adhesion
  • MST1
  • STK4

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