Occurrence of HTLV-I antibodies in Danish patients with cutaneous T-cell lymphoma

10 of 68 CTCL (cutaneous T-cell lymphoma) patients without features of ATLL had antibodies against HTLV-I (human T-cell leukaemia virus, type I). The titre of antibody in these positive patients was generally much lower than that seen in cases of ATLL (adult T-cell leukaemia/lymphoma); geometric mean of 80 for CTCL vs. 8000 for Caribbean ATLL. The presence of HTLV-I antibody was unrelated to clinical remission, relapse, or stages of the disease, and some positives were detected in the earliest phases of mycosis fungoides. Among controls and normal donors between the ages of 40 and 65, only 1 of 36 and 3 of 113, respectively, had low titre antibodies to HTLV-I in their sera. Only 5 of 354 Danish normal donors of all ages had antibody, which was identical to the rate in over 2000 US normal donors. In negative control experiments, these antibodies were unreactive with bovine leukaemia virus. These data suggest that HTLV-I or a related retrovirus crossreactive with HTLV-I occurs in a low percentage of the Danish population and patients with CTCL have such antibodies at an increased rate, but less than the rate seen for ATLL (greater than 90%).