Intrathecal synthesis of IgG antibodies to HTLV-I supports an etiological role for HTLV-I in tropical spastic paraparesis.

High titers of antibody to human T-lymphotropic virus type I (HTLV-I) have been reported in the sera and cerebrospinal fluids of patients with tropical spastic paraparesis. By means of agarose isoelectric focusing and selective immunoblotting, we demonstrated oligoclonal bands of immunoglobulin G antibodies to HTLV-I in the serum and cerebrospinal fluid of patients with tropical spastic paraparesis. Such cerebrospinal fluid-specific immunoglobulin bands indicate intrathecal synthesis of specific antibodies to HTLV-I. These findings mimic the antibody response to measles virus in subacute sclerosing panencephalitis and support an etiological role for HTLV-I in the pathogenesis of tropical spastic paraparesis.