ANTIBODY-DEPENDENT CELL-MEDIATED CYTOTOXICITY (ADCC) IN HTLV-I-ASSOCIATED MYELOPATHY TROPICAL SPASTIC PARAPARESIS (HAM/TSP)/

Defects in immune surveillance mechanisms may allow increased replicat ion of human T-lymphotropic virus type I (HTLV-I) in peripheral blood mononuclear cells in HTLV-I associated myelopathy/tropical spastic par aparesis (HAM/TSP). To explore this possibility, antibody-dependent ce ll-mediated cytotoxicity (ADCC) against HTLV-I infected cells in HAM/T SP and in asymptomatic HTLV-I-seropositive carriers (SPC), was studied . ADCC activity was significantly depressed in HAM/TSP compared to SPC subjects (p < 0.025) and was due to specific reduction in ADCC effect or activity. On the other hand, there was no difference in antibody co mponent of anti-HTLV-I ADCC (ADCC-Ab) activities between HAM/TSP and S PC, although patients with more severe forms of disease tended to have higher anti-HTLV-I ADCC-Ab activity. In HAM/TSP, depressed ADCC activ ity against HTLV-I due to reduced ADCC-effector activity may allow inc reased replication of HTLV-I which may implicate the development of in flammatory neuropathologic lesions of HAM/TSP.