Antigenic specificity of sorted CD4⁺ and CD8⁺ T cells. CFSE-stained PBMC cultures from a patient with MS were stimulated with GA for 7 days, followed by flow cytometric sorting of proliferating CD4⁺ or CD8⁺ T cells into a 96-well plate at 10 cells and 5 cells per well, respectively, followed by expansion with rounds of PHA and IL-2 stimulation for 4 weeks. ³H-Thymidine-based proliferation assays were then performed in the presence of no antigen (□), GA (▪), or Con A () (24 wells per condition). The y-axis represents mean CPM of 24 wells + 2 SEM. Using a cutoff of mean background counts + 2 SD, 24 of 24 Con A-stimulated wells showed positive responses in both cases. Of GA-stimulated wells, 24 (100%) of 24 CD4⁺ wells and 20 (83%) of 24 CD8⁺ wells showed positive responses, with counts from positive wells approximating those from Con A-stimulated wells.