title: Interleukin-2 gene expression in different phases of episodic cluster headache--a pilot study.
abstract: BACKGROUND
  The pathophysiology of cluster headache (CH) is still largely unknown. Immunological mechanisms have been suggested to be of importance.
  
  
  OBJECTIVE
  This study aimed to investigate cytokine interleukin-2 (IL-2) as a possible marker of immune system involvement in the pathophysiology of CH.
  
  
  METHODS
  Eight episodic patients with CH and 16 healthy headache-free control subjects matched for age and gender were studied. Venous blood samples were drawn from the patients with CH on three occasions; during active period between headache attacks, during an attack and in remission. Venous blood samples were drawn once from each control subject. We analysed IL-2 gene expression, using quantitative real-time polymerase chain reaction.
  
  
  RESULTS
  Patients with CH had significantly increased relative IL-2 gene expression levels between headache attacks during active CH period (median 9.9 IL-2 cDNA/glyceraldehyde-3-phosphate dehydrogenase cDNA; IQR 6.2-10.3) compared to during attacks (median 2.8; IQR 0.7-3.2, P = 0.012), remission (median 1.6; IQR 0.9-1.8, P = 0.017) and controls (median 0.9; IQR 0.6-1.9, P = 0.0001).
  
  
  CONCLUSIONS
  The increment of IL-2 found during the active CH period may support a role for this cytokine and subsequently for the immune system in the pathophysiology of CH. An expansion of this study to a broader group of cytokines and a larger patient cohort is warranted.
authors.affiliation: Department of Clinical Neuroscience, Division of Neurology, Karolinska Institutet, Karolinska University Hospital Huddinge, Stockholm, Sweden. anna.steinberg@karolinska.s
authors.forename: A
authors.initials: A
authors.lastname: Steinberg
authors.forename: C
authors.initials: C
authors.lastname: Sjöstrand
authors.forename: A
authors.initials: A
authors.lastname: Sominanda
authors.forename: A
authors.initials: A
authors.lastname: Fogdell-Hahn
authors.forename: A I M Nilsson
authors.initials: AI
authors.lastname: Remahl
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D016022:Case-Control Studies; D003027:Cluster Headache / Q000235:genetics* / Q000503:physiopathology*; D005260:Female; D015870:Gene Expression / Q000502:physiology*; D006801:Humans; D007376:Interleukin-2 / Q000235:genetics* / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D010865:Pilot Projects; D018709:Statistics, Nonparametric
chemical_list: D007376:Interleukin-2