SummaryTo investigate the in vivo cellular tropism of human T cell leukemia virus type II (HTLV-II), subpopulations of fresh peripheral blood mononuclear cells from infected individuals were isolated and analyzed by polymerase chain reaction for the presence of provirus. In eight of nine patients, HTLV-II was detected exclusively in the CD8 + T lymphocyte population. In the remaining patient, provirus was also detected in CD4 + T lymphocytes. Provirus was not detected in B lymphocytes or monocytes of any patient. These results suggest that in vivo HTLV-II has a preferential, and perhaps in some cases, an exclusive tropism for CD8 + T lymphocytes. The findings contrast sharply with those on HTLV-I where there is a preferential tropism for CD4 + T lymphocytes. Although HTLV-II infection has not been consistently associated with any lymphoproliferative disorders, the results suggest that if these occur, they may be different from those known to be associated with HTLV-I.T he human T cell leukemia viruses, type I (HTLV-I) and type II (HTLV-II) are members of a group of retroviruses having similar biological properties and a tropism for T lymphocytes (1-3). HTLV-I is endemic in well-defined geographic areas, and although the majority of infected individuals remain asymptomatic, infection is associated with adult T cell leukemia (ATL), a malignancy of mature CD4 + T lymphocytes (4-6) and a chronic neurologic disorder known as HTLV-I associated myelopathy/tropical spastic paraparesis (HAM/TSP) (7,8). HTLV-II infection has recently been shown to be endemic in certain New World native Indian populations (9-11), and high rates of infection have also been demonstrated in intravenous drug abusers (IVDAs) in North America (12)(13)(14). Infection however, has not yet been definitely associated with disease. Whereas the virus was originally isolated from two patients with atypical variants of hairy cell leukemia (15, 16), subsequent studies have failed to reveal an association of HTLV-II infection with this disorder (11,17). The apparent lack of pathogenidty of HTLV-II remains poorly understood. Although this may only reflect the relatively small number of individuals so far identified with infection, it may also be related to inherent properties of the virus and/or its cellular tropism. Recent studies using the PCR have demonstrated that HTLV-I has a preferential tropism for CD4 + T lymphocytes in both asymptomatic patients and those with neurological disease (18). In the present study, we have used similar methods to determine the in vivo tropism of HTLV-II, and demonstrate, in contrast to HTLV-I, that the virus has a preferential tropism for CD8 + T lymphocytes. Materials and MethodsSubjects. Nine patients with HTLV-II infection were studied. HTLV-II infection was confirmed by virus isolation and PCR amplification using methods previously described (14). Four of the patients were also infected with HIV (Table 1). All patients, except three (B.V., J.V., and W.F.) had a history of intravenous drug abuse. Written informed cons...

No abstract