In this thesis, immunological parameters in multiple sclerosis patients (MS) have been examined and techniques contributing to the study of these aspects have been developed. The epidemiology of MS suggests that both environmental and genetic factors contribute to the disease process. According to a widespread theory, an autoimmune reaction leading to demyelination could be induced, in genetically determined individuals, by an infectious agent (s) e.g a paramyxovirus or a retrovirus. In the first part of the thesis, the oligoclonal immunoglobulin (Igs) in the CSF of MS patients in relation to the paramyxovirus SV5 were studied. This was to complement an initial observation made in the department that a significant proportion of cerebrospinal fluids (CSF) could have oligoclonal bands directly acting against antigens (Ags) of this virus. In the second part of the thesis, techniques were developed for the analysis of proliferative capacity of peripheral lymphocytes of MS and control patients using possible MS autoantigens viz myelin and brain vessels. The humoral response against these Ags was also assessed by immunoblotting using MS, neurological and normal control patients. In parallel and in the view to obtaining antigens for the immunological studies, techniques for the purification and characterisation of human brain vessels from post mortem brains were assessed and attempts to culture human brain endothelial cell lines were made.