The immune response in human demyelinating diseases.

Lymphocytes present in the brain, meninges and cerebrospinal fluid (CSF) in multiple sclerosis (MS) are capable of synthesizing IgG. The CSF in MS contains more T-lymphocytes and fewer B-lymphocytes compared to blood. The reactivity of CSF lymphocytes in MS to T-cell mitogens and probably also to a combined B-and T-cell mitogen is absent or heavily reduced. This unresponsiveness of CSF lymphocytes may be a consequence of their previous activation. The blood lymphocytes in MS are not altered regarding distribution of B-and T-cells, nor regarding responsiveness to mitogens, when compared with healthy controls. An asynchronous synthesis of heavy and light immunoglobulin chains occurs within the CNS in many MS patients, giving rise to oligoclonal band patterns on electrophoresis and abnormal kappa/lambda light chain ratios of CSF. The synthesized immunoglobulins are most probably antibodies which may play a role in the pathogenesis and course of human demyelinating diseases. The brain must be regarded, from an immunological point of view, as a privileged site with its own immune system and its characteristic immune reactions, and future research concerning demyelinating diseases should, if possible, include investigations of these reactions.