Mixed lymphocyte reaction in multiple sclerosis.

The mixed lymphocyte reaction (MLR) as measured by the macrophage electrophoretic mobility (MEM) test is markedly reduced between unrelated multiple sclerosis (MS) patients. This is not the case with other neurological diseases (OND). Within an MS family, the MLR between the propositus and members of the family falls into the low (MS type) range or into the normal or OND range. Those members who give the low results are those who have a MEM-LAD test result of about 77 per cent, i.e. halfway between that of normal and MS. There is thus a parallelism between the anomalous response to linoleic acid and an unexpectedly low MLR with known MS lymphocytes. Lymphocytes from apparently normal children who have a high (MS-type) linoleic acid depression result take part in an MLR with MS cells, as if they were themselves true MS cells. Some possible implications these findings may have for the pathogenesis of MS are discussed.