Measurement of Cell-Mediated Inflammation in Experimental Murine Autoimmune Encephalomyelitis by Radioisotopic Labeling

Abstract

A radioisotopic index test was used to detect that time of onset and intensity of cell-mediated immune inflammation of experimental autoimmune encephalomyelitis (EAE) in mice. Mice were tested at various time intervals after an encephalitogenic immunization with mouse spinal cord homogenate for delayed-type hypersensitivity (DTH) to myelin basic protein (MBP) by intradermal challenge with antigen in the ear pinna. After 24 hr, the intensity of DTH was measured by ¹²⁵I-radiometry which depends upon the migration of ¹²⁵I-UdR radiolabeled mononuclear cells into the antigen depot. Cells reactive to MBP were detected by the ear assay as early as 7 days after the initial encephalitogenic sensitization. The degree of cell-mediated immune inflammation in the brain and spinal cord during the evolution of EAE was also measured by a radioisotopic technique; increased ¹²⁵I-UdR uptake could be detected in the brain 3 to 4 days before the onset of signs of EAE at days 11 to 12, whereas ¹²⁵I-UdR in the spinal cord was detected only 1 day before, or concomitant with, the onset of signs of EAE. Both the “ear” and “organ” radiometric index tests are useful in measuring the degree of cell-mediated inflammation in EAE, and supplement routine histopathological and observational assessments.