The effects of Low-dose IL-2 immunotherapy on immune cells in Amyotrophic Lateral Sclerosis – an incurable motor neuron disease with immune driven pathologies

Student thesis: Doctoral ThesisDoctor of Philosophy


Amyotrophic lateral sclerosis (ALS) is a rare neurological disorder characterised by the loss of motor neurons that control voluntary muscles, leading to progressive paralysis and death. There is no cure, and approved drugs prolong survival by 3-6 months only. The events that trigger ALS are poorly understood, however recent findings indicate a role for inflammation and a lack of immune regulation in the prognosis of ALS.
To this end we carried out the first placebo-controlled, low-dose (LD) interleukin-2 (IL-2) immunotherapy trial in ALS patients with the aim of improving regulatory T cell (Treg) numbers. IL-2 therapy has been used to expand Treg in vivo but the expansions observed vary greatly between individuals and an improvement in Treg function is not always observed.
The aim of this project was to assess the effects of IL-2 on lymphoid and myeloid cell number, phenotype, function and IL-2 signalling. We observed significant expansion of Treg, natural killer (NK) cells, effector T cells and cytotoxic T lymphocytes in blood. The data also show changes in monocyte subsets in those receiving the highest dose of IL-2. Comprehensive phenotyping showed significant expansion of highly activated and proliferative Treg subsets and suggested an induction of Treg generation in the thymus. IL-2 also expanded NK subsets that have been shown to have disease modifying actions in other conditions, while assessment of monocyte phenotypes show a reduction in non-classical monocyte subset with high migratory potential. In vitro co-culture assays showed a significant increase in Treg suppressive function. While IL-2 signaling analysis showed a significant decrease in IL-2 signaling in Treg, and increased IL-2 signaling in cytotoxic T lymphocytes at the highest dose of IL-2. In this thesis, we have shown that IL-2 therapy can effectively improve Treg number and function and, is safe and well tolerated in ALS patients. However, more work is needed to determine the dose/frequency or delivery system of IL-2 for optimal Treg expansion and maintenance of elevated numbers. Furthermore, the clinical efficacy of IL-2 in ALS is unknown but is currently being assessed in a phase II clinical trial.
Date of Award1 Nov 2021
Original languageEnglish
Awarding Institution
  • King's College London
SupervisorTimothy Tree (Supervisor) & Mark Peakman (Supervisor)

Cite this