Decreased serum interleukin-2 level in patients with chronic headache

Some cellular immune functions are impaired in cluster headache patients. Interleukin-2 (IL-2) is a polypeptide secreted by antigen or mitogen-actuated T lymphocytes that functions as a growth factor for T cells. To investigate cellular immune functions in patients with chronic headache, we measured the IL-2 concentration of sera in patients with migraine and in patients with tension-type headache. Thirteen subjects suffering from migraine without aura (5 males and 8 females, mean age: 32.8 years) and 46 subjects (20 males and 26 females, mean age: 39.7 years) with tension-type headache (TH) were selected for this study. Forty-three normal healthy volunteers composed the control group (15 males and 28 females, average age 41.6 years). The IL-2 levels of sera were determined using enzyme-linked immunosorbent assay (ELISA) techniques. The IL-2 levels of sera were 3.18 +/- 1.8 U/ml (mean +/- SD) in the healthy controls, 2.29 +/- 2.6 U/ml in the patients with migraine and 1.59 +/- 1.0 U/ml in the patients with TH. The serum level of IL-2 in the patients with migraine was significantly lower than in the controls. The serum level of IL-2 in the patients with TH was significantly lower than in the controls. The central nervous system (CNS) has been considered to be involved in the development of the immune phenomena. In the patients with TH or migraine, reduction in platelet 5-hydroxytryptamine (5-HT) levels and sympathetic hypofunction have been observed. These phenomena might reflect decrease in 5-HT levels in CNS in the patients with TH or migraine. The decreased serum IL-2 level, observed in this study, might reflect a reduction in 5-HT or catecholamine levels in CNS in the patients with migraine or TH.