CD80 and Guillain-Barre syndrome: Although enhanced expression of other costimulatory molecules has already been shown in GBS, such as the CD80 and CD86 (i.e., the B7-1 and B7-2 costimulatory molecules) (48) and the inducible T-cell costimulator (49), the CD40L was first shown in our report to be involved in pathogenesis and be a potential biomarker in the acute phase of GBS.