Separation and properties of lymphocytes obtained from the central nervous system.

To study immune responses in inflammatory diseases of the central nervous system (CNS) we have devised a method of removing lymphocytes from brain and spinal cord. Experimental allergic encephalomyelitis was induced in adult Hartley guinea pigs to produce CNS inflammation. Brain and cervical spinal cord were removed and minced. The single-cell suspension was centrifuged on a modified Ficoll-Hypaque gradient. Lymphocytes passed through to the pellet, while brain cells stayed at the top of the gradient. An average of 1.7 x 10(6) lymphocytes was obtained from a single guinea pig brain and cervical spinal cord. When the CNS lymphocytes were cultured in the presence of phytohemagglutinin (PHA) or purified protein derivative (PPD) proliferative responses were obtained. No proliferative responses occurred when CNS lymphocytes were cultured with myelin basic protein. Using this technique, viable lymphocytes can be separated from inflamed CNS and can be cultured in vitro to measure cell-mediated immune responses.