Standardisation of Western blotting to detect HTLV-1 antibodies synthesised in the central nervous system of HAM/TSP patients

Intrathecal synthesis of human T-lymphotropic virus type 1 (HTLV-1) antibodies(Abs) represents conclusive evidence of a specific immune response in thecentral nervous system of HTLV-1 associated myelopathy/tropical spasticparaparesis (HAM/TSP) patients. Western blotting (WB) for HTLV Abs in serum is aconfirmatory test for HTLV-1 infection. The aim of this study was to standardisethe Western blot to demonstrate the intrathecal pattern of Abs against HTLV-1proteins in HAM/TSP patients. Paired cerebrospinal fluid (CSF) and serum sampleswere selected from 20 patients with definite HAM/TSP, 19 HTLV-1 seronegativepatients and two HTLV-1 patients without definite HAM/TSP. The presence ofreactive bands of greater intensity in the CSF compared to serum (or bands inonly the CSF) indicated the intrathecal synthesis of anti-HTLV-1 Abs. Alldefinite HAM/TSP patients presented with an intrathecal synthesis of anti-HTLV-1Abs; these Abs were not detected in the control patients. The most frequentintrathecal targets of anti-HTLV-1 Abs were GD21, rgp46-I and p24 and, to alesser extent, p19, p26, p28, p32, p36, p53 gp21 and gp46. The intrathecalimmune response against env (GD21 and rgp46-I) andgag (p24) proteins represents the most important humoralpattern in HAM/TSP. This response may be used as a diagnostic marker,considering the frequent association of intrathecal anti-HTLV-1 Ab synthesiswith HAM/TSP and the pathogenesis of this neurological disease.