MACROPHAGES, LYMPHOCYTES, AND PLASMA-CELLS IN PERIVASCULAR COMPARTMENT IN CHRONIC MULTIPLE-SCLEROSIS

  • 1 January 1978
    • journal article
    • research article
    • Vol. 38  (4) , 409-421
Abstract
Perivascular cells in CNS tissue from 6 multiple sclerosis (MS) patients and a patient with motor neuron disease were examined by light microscopy and EM. Lymph node tissue from 1 MS patient was also examined. CNS perivascular macrophages in MS and motor neuron disease closely resembled free macrophages elsewhere in the body except that they often contained unusually large primary lysosomes. Cytoplasmic inclusions consisting of membrane-bound stacks of curved linear profiles, presumed to be a product of myelin degradation, were constantly observed in macroglia in MS plaques but were rarely observed in perivascular macrophages in the same area. Unidentified cylindrical bodies were observed within cysternae of rough endoplasmic reticulum in some lymph node cells. Quantitative studies of the perivascular cell population in 1 MS case revealed, in histologically normal white matter, 260 lymphocytes and 178 plasma cells/mm3 of fresh tissue. Typical chronic plaque tissue without obvious inflammatory cell cuffing contained 1772 plasma cells/mm3 of fresh tissue. No plasma cells were observed in the CNS in motor neuron disease. Perivascular macrophages in the CNS probably represent a specialized population of monocyte-derived free macrophages, these cells probably differ functionally from microglial cells, and the digestion of myelin breakdown products in MS probably requires the participation of both cell types. In some chronic MS cases there may be a large, permanent population of CNS plasma cells that persists, like the elevated cerebrospinal fluid Ig[immunoglobulin]G level in this disease, for the life of the patient. These cells, rather than inflammatory cells in fresh lesions, are probably the major source of this raised IgG and the existence of such a population of cells may indicate the continuing expression of antigens in chronic MS lesions in the absence of fresh lesion formation.