BMT at peak of acute disease. Day 150 splenocyte proliferative response to increasing concentrations of disease-initiating (PLP 139-151) and relapse-associated (PLP 178-191) epitopes of PLP. The number above each bar is the stimulation index (ratio of CPM with antigen divided by CPM without antigen). Splenocytes from naive mice did not respond to PLP 139-151 or PLP 178-191. CPM, counts per minute; α-CD3, stimulation by the antibody to the T-cell receptor.