Human T-cell leukemia virus (HTLV) in the United Kingdom.

Ten out of 26 leukaemic patients who had emigrated from the Caribbean region to the United Kingdom had adult T-cell leukaemia with associated serum antibodies to HTLV I. Antibodies to HTLV were also detected in sera from a small proportion of non-leukaemic Caribbean immigrants but not in any sera from other (non-ATL) T-cell leukaemias or a variety of control groups. The long period between immigration to the UK and diagnosis of leukaemia (up to 30 years) suggests that an extensive latent period in disease development may exist. Cell lines were isolated from two patients with HTLV antibody-positive ATL and were shown to be virus-positive by electron microscopy and immunofluorescence using antibodies to the p19 and p24 viral proteins. HTLV1 provirus integration and active transcription were demonstrated by Southern blotting of DNA and in situ hybridization respectively using molecularly cloned HTLV1 probes. Virus from one of these cell lines could be transmitted to normal T cells by co-cultivation.