Circulating brain derived neurotrophic factor (BDNF) and frequency of BDNF positive T cells in peripheral blood in human ischemic stroke: Effect on outcome

The aim of this study was to measure the levels of circulating BDNF and the frequency of BDNF-producing T cells after acute ischaemic stroke. Serum BDNF levels were measured by ELISA. Flow cytometry was used to enumerate peripheral blood leukocytes that were labelled with antibodies against markers of T cells, T regulatory cells (Tregs), and intracellular BDNF. There was a slight increase in serum BDNF levels after stroke. There was no overall difference between stroke patients and controls in the frequency of CD4+ and CD8+ BDNF+ cells, although a subgroup of stroke patients showed high frequencies of these cells. However, there was an increase in the percentage of BDNF+ Treg cells in the CD4+ population in stroke patients compared to controls. Patients with high percentages of CD4+ BDNF+ Treg cells had a better outcome at 6 months than those with lower levels. These groups did not differ in age, gender or initial stroke severity. Enhancement of BDNF production after stroke could be a useful means of improving neuroprotection and recovery after stroke.