title: Soluble interleukin-2 receptors increase during the active periods in cluster headache.
abstract: OBJECTIVE
  To investigate whether cytokines are altered during the active period of cluster headache.
  
  
  BACKGROUND
  Patients with cluster headache show activation of the hypothalamus in PET studies and via endocrinologic parameters. Data also suggest an inflammatory process occurs in cluster headache. A connection between the presumed inflammatory cause, an immunological activation, and the hypothalamus could be generated by certain cytokines.
  
  
  METHODS
  ELISA was used to determine the serum levels of soluble interleukin-2 receptors, interleukin-1, interleukin-6, and 2 soluble interleukin-6 receptors (sIL-6R and soluble gp130) in 18 patients with cluster headache (6 women and 12 men) during the cluster period and in 17 healthy controls who were headache-free (3 women and 14 men).
  
  
  RESULTS
  Patients with cluster headache had significantly increased soluble interleukin-2 receptors (413.6+/-223 U/mL vs. 290.0+/-112 U/mL; P <.05) compared with controls. Serum levels of interleukin-1 (0.29+/-0.30 pg/mL vs. 0.13+/-0.13 pg/mL, n.s.), interleukin-6 (0.87+/-0.6 pg/mL vs. 0.91+/-0.7 pg/ml; n.s.), soluble interleukin-6 receptors (33,131+/-8,349 pg/mL vs. 35,063+/-7,606 pg/mL; n.s.), or soluble gp130 (289+/-59 pg/mL vs. 283+/-20 pg/mL; n.s.) did not differ between the 2 groups, although patients with cluster tended to have higher interleukin-1 values.
  
  
  CONCLUSIONS
  Because elevated soluble interleukin-2 receptors indicate T cell activation, our findings suggest immune activation during cluster headache. Because interleukin-2 can activate the hypothalamus and stimulate the release of Corticotropin-releasing Factor (CRF), interleukin-2 could link a putative immunological cause of cluster headache with the observed hypothalamic activation. Systemic changes of interleukin-1 or the interleukin-6 system do not seem to play a role in cluster headache, as no alterations of serum levels were observed. Even so, unchanged serum levels do not exclude limited local production.
authors.affiliation: Department of Neurology, Ludwig-Maximilians University, Munich, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Empl
authors.forename: S
authors.initials: S
authors.lastname: Förderreuther
authors.forename: M
authors.initials: M
authors.lastname: Schwarz
authors.forename: N
authors.initials: N
authors.lastname: Müller
authors.forename: A
authors.initials: A
authors.lastname: Straube
mesh_terms: D000328:Adult; D003027:Cluster Headache / Q000097:blood* / Q000276:immunology / Q000378:metabolism; D005260:Female; D006801:Humans; D007031:Hypothalamus / Q000503:physiopathology; D007378:Interleukins / Q000097:blood; D008297:Male; D015375:Receptors, Interleukin-2 / Q000097:blood* / Q000276:immunology; D019947:Receptors, Interleukin-6 / Q000097:blood; D012995:Solubility; D013601:T-Lymphocytes / Q000276:immunology / Q000378:metabolism
chemical_list: D007378:Interleukins; D015375:Receptors, Interleukin-2; D019947:Receptors, Interleukin-6