Evaluation of Donor-Derived B Cell Infusions in Patients With Amyotrophic Lateral Sclerosis (ALS)

This study is testing whether giving people with ALS specially matched immune cells called B cells from a related donor is safe. Up to 10 participants will each receive two B cell infusions at least 60 days apart. The main goals are to watch closely for side effects, see whether the participant's immune system rejects the donor cells, and determine whether this treatment should be studied further in people with ALS. The first three participants will receive the infusions in the hospital with extra safety spacing between participants; if those infusions appear safe, the remaining participants may receive them in an outpatient setting.