IL2 and viral encephalitis: Based on IL-2 in migraine group [2.16 (1.62) pg/mL], in encephalitis with headache group [1.67 (1.22) pg/mL], and in pneumonia without headache group [2.18 (3.07) pg/mL], there were statistical differences in the overall distribution of IL-2 among the three groups (H = 6.80, p = 0.033).