CD4 and tropical spastic paraparesis: Furthermore, despite both correlating strongly, the rs value for the two CD4 + T cell activation markers was nearly double that of the CD8 + T cell activation markers (0.58 and 0.63 v 0.35 and 0.39) (Supplementary Table 2), highlighting the importance of CD4 + T cells in HAM pathophysiology where the role of the CD8 response has often been emphasised.