CD4 and migraine disorder: Other studies from the last decade have shown, among other things, a reduction in CD4 + CD25 + regulatory T cells in migraine; changes in lymphocyte subsets in paediatric migraine (lower CD8 + prevalence and a higher CD4 + /CD8 + ratio in the ictal phase irrespective of migraine subtype); higher CD3, CD4, CD8 and CD19 in patients with chronic migraine compared to patients with episodic migraine; and an increased proportion of Treg CD45R0 + CD62L– and CD45R0–CD62L– cells12–15.