Cytopherometry in neurologic diseases is discussed with regard to antigenic reactivity, the formation of cytokines and the direct changes of electrophoretic mobility of immune-competent cells. The Macrophage-Electrophoresis-Mobility (MEM) test, the variants of the method and additional techniques produced some results of diagnostic and immunpathologic value. A general and unspecific sensitization during cellular immune reaction in lesions of the nervous parenchyma was detectable. Using adequate antigens and extended methods of characterisation in the test system, differentiated reactivity, mainly of the inflammatory diseases and in some pathogenetic processes - including a defect of cell-membrane - was found. Typical findings were shown with the MEM-LAD (linoleic acid depression) test in M.S. This technique led to novel pathogenetic, family-genetic and therapeutic aspects. Similar diagnostic progress in various types of brain tumors was shown by using tumorassociated antigens. Analysis of specific factors of cellular immunity was extented by developing a thymosine assay and direct assessment of cytokines, especially fo the MSF (macrophage slowing factor) in the MSF assay. The thymosine assay may prove valuable for the cellular basis of immunologic processes (in particular myasthenia and therapeutic thymectomy). With the direct MSF assay a differentiated high MSF activity in the CSF in chronic neuroimmunologic processes and particularly in M.S. was shown which led to novel aspects of the immunology of the CSF. The characteristics of the MSF, found after column-chromatographic fractionation, showed identical zytokine activity in CSF and the supernatants of lymphocyte-antigen-incubation which lay in the lower range of molecular weight of migration inhibitory lymphokines.