We used competitive polymerase chain reaction to quantify messenger RNA for the lymphocyte antigens CD4 and CD8, the adhesion molecules ICAM-1 and VCAM-1, and the MHC class II I-A molecule in the spinal cords of SJL/J mice at multiple times during the development and resolution of experimental allergic encephalomyelitis (EAE). CD4 and CD8 were not quantifiable at baseline, became detectable at 5 days after immunization, and increased steadily to a peak during clinical disease. I-A increased after CD4 and CD8, but before onset of disease. ICAM-1 and VCAM-1 did not increase until after onset of clinical disease. CD4, CD8, and I-A remained elevated long after recovery from disease. These results suggest that infiltration of CD4 and CD8 cells into the spinal cord and subsequent upregulation of I-A mRNA play an important role in the development of EAE, but reversal of these processes is not necessary for recovery. Upregulation of ICAM-1 and VCAM-1 mRNA does not appear to be important for development of disease.