Allolymphocytotoxic antibodies in sera from HTLV-I-associated myelopathy/tropical spastic paraparesis patients — putative anti-HLA antibodies

Thirty-one HTLV-I-associated myelopathy/tropical spastic paraparesis (HAM/TSP) patients and 34 asymptomatic carriers were studied in order to investigate the presence of anti-lymphocyte antibodies in their sera. 32% of the patients produced allolymphocytotoxic antibodies reactive to peripheral blood lymphocytes (mainly T cells) as well as to B cells, which belonged to the IgM class, reacted under warm and cold conditions, and showed specificity to multiple HLA antigens, especially HLA A2, A26, A33, B7, B27, B35, B48, B61 and Cw3. Moreover, their reactivities could be absorbed by pooled platelets. Therefore, it may be suggested that either anti-HLA class I antibodies or antibodies cross-reactive to HLA were present. On Western blot analysis, the HAM/TSP cytotoxic sera reacted to the 110 kDa molecules of lymphocyte lysates. In the case of carriers, weak cytotoxic antibodies were detectable in 14% of the sera. No multispecificity to HLA class I antigens was observed and there was no reactivity to the 110 kDa band. The production of allolymphocytotoxic antibodies in HAM/TSP patients may therefore be explained by the presence of allogeneic-like stimuli in this disease. HTLV-I infected cells, expressing altered HLA antigens could possibly account for this stimulation and also contribute to the alteration of immune functions in HAM/TSP, and thus play an important role in its pathogenesis.