Although earlier work reported that activity and frequency of NK or NK-like cell response in HAM/TSP patients did not correlate with proviral load (33-35), Vine et al, 2004 indicated high levels of NKG2D gene expression, which served as a primary recognition receptor on NK cells, and a costimulatory molecule on CTLs were linked with HTLV-I low proviral load. Here, KLRK1 is linked to tropical spastic paraparesis.