A humoral lymphocyte transformation inhibition factor in multiple sclerosis

A humoral factor having many of the physical properties of a glycoprotein and lacking many of the characteristics of other immunosuppressants has been detected in the serum and plasma of patients with active multiple sclerosis. Kinetic studies indicate that the earliest biochemical event inhibited by LTIF is the incorporation of labeled nucleotides into acid insoluble ribonucleic acid. This material, designated lymphocyte transformation inhibition factor (LTIF), inhibits blast transformation in mitogen-stimulated T lymphocytes. The serum factor is usually associated with active multiple sclerosis but is also detected in some lymphoproliferative disorders. Partial purification has separated this material from serum immunoglobulins, but these procedures led to an accelerated loss of biological activity.