Another mechanism is described for HSP60 E18 mutants (90–109, HSP60 APL1:L109, Hsp60 APL2:L103) that are effective in both increasing the proportion of Treg and suppressing IL-17 level, and APL-1 is further effective in inducing apoptosis in autoreactive CD4+ CD25+ T cell and increasing IL-10 levels when incubated with PBMC from RA patients [111,112,113] (Figure 3). Here, CD4 is linked to rheumatoid arthritis.