CD4 and amyotrophic lateral sclerosis: In mouse studies of ALS, CD4 + T-lymphocytes and M2 microglia/macrophages actively contribute to neuroprotection in the early neuroprotective phase of the disease, whereas in the late cytotoxic phase, the deleterious response of CD8 + T-lymphocytes and M1 microglia/macrophages and suppression of regulatory T-lymphocytes are major contributors to the motor neuron degeneration3,31.