CSF2 and myeloid sarcoma: Additional elegant work examining both CSF B cell IgG-H and Ig-κ chains transcriptomes, as well as the oligoclonal Ig proteomes derived from the same CSF of patients with relapsing-remitting MS, showed a correspondence between CSF Ig proteomes and B cell Ig transcriptomes, providing the most direct evidence that expanded CSF B cell clones are responsible for producing the abnormal Ig that comprises the CSF OCB in MS patients (73).