Analysis of B-cell activation of cerebrospinal fluid lymphocytes in multiple sclerosis

We have developed a microculture system to study pokeweed mitogen (PWM)-induced B-cell differentiation responses of CSF lymphocytes from patients with multiple sclerosis (MS) and other neurologic diseases (OND). B-cell differentiation was assessed by (1) enumeration of immunoglobulin-secreting cells (IgSC) by a protein A reverse hemolytic plaque assay; and (2) quantitation of supernatant IgG by ELISA. Cultures of MS CSF cells and OND CSF cells responded to PWM with a similar frequency, with responses in CSF cell cultures exceeding responses in corresponding blood cell cultures in several instances in both groups of patients. Numbers of IgSC in unstimulated cultures of MS CSF cells exceeded numbers in cultures of autologous peripheral blood mononuclear cells (PBM). Results suggest that CSF cells may be a particularly reactive population compared with PBM.