Complement activation in migraine.

Forty patients attending the Prince Henry Hospital migraine clinic have been investigated for evidence of complement activation related to migraine. These patients had a history of clinically similar migraine attacks. Levels of serum complement components were determined in nine patients, both in and out of migraine. Comparison of these levels showed significant reductions in C4 and C5 during headache. In a further 31 patients C3 breakdown products were sought when these patients were headache-free. They were detected in the plasma of three patients who proceeded to a migraine attack but not in the plasma of the remaining twenty-eight who did not. These findings suggest the presence of complement activation, which could explain many of the previously reported phenomena associated with migraine.