Studies have shown that microbial-reactive, IgA-producing plasma cells migrate from the gut to the CNS during active MS flares,17,18 and there have been reports of cerebrospinal fluid (CSF)-restricted IgA synthesis in the early stages of MS.45 Our data suggest that in patients with MS, IgA-secreting lymphocytes within the gut mucosa may generate antibodies with impaired antigen recognition, potentially contributing to microbial dysregulation. The gene discussed is CD79A; the disease is myeloid sarcoma.