Importance of intrathecal synthesis of IgD in multiple sclerosis. A combined clinical, immunologic, and magnetic resonance imaging study.

There is increasing evidence that soluble IgD has a certain role in the humoral immune response within the central nervous system. We report herein the results of a combined clinical, magnetic resonance imaging, and immunopathologic study to determine the clinical importance of intrathecal IgD synthesis. Intrathecal synthesis of IgD (detected through the calculation of index values) was studied in 64 patients with multiple sclerosis and in 50 neurologic control patients and normal subjects. Locally secreted IgD was detected in 30% of patients with clinically active multiple sclerosis, including two in whom magnetic resonance images of brain and spinal cord were normal and who had no evidence of intrathecal IgG synthesis. No intrathecal IgD production was detected in patients with clinically stable multiple sclerosis or those suffering from chronic progressive multiple sclerosis, while it significantly correlated with the interval from the last relapse and with the total duration of the disease process in patients with relapsing, remitting multiple sclerosis. Intrathecal IgD synthesis also correlated with the degree of cerebrospinal fluid pleocytosis and with the presence of free kappa and lambda light chain bands in cerebrospinal fluid. Present results supplement and expand earlier data and suggest that intrathecally secreted IgD is a putatively important part of the immune response in clinically active relapsing, remitting multiple sclerosis.