High dose cyclophosphamide preferentially targets naïve T (CD45/CD4/RA+) cells in CIDP and MS patients

T cells occupy a central role in MS and CIDP pathogenesis. High dose cyclophosphamide's in-vivo cytotoxic-effect on circulating memory and naïve T cells is unknown.Three MS and five CIDP patients received cyclophosphamide (200 mg/kg) for refractory disease. Before and after chemotherapy administration, peripheral blood T-cell subsets were determined. Patients underwent serial neurologic evaluations quarterly.Cyclophosphamide uniformly decreased clinical disease activity. Compared to memory T cells, naïve T cells were preferentially eradicated.Cyclophosphamide effectiveness in autoimmune illness may result from Naïve T-cell destruction, as this compartment may be the source of autoreactive lymphocytes.