Monoclonal integration of HTLV-1 in pleural effusion cells in a seropositive patient with tuberculous pleuritis.

The pleural effusion of a 79-year-old man who was a carrier of human T-cell leukemia virus type 1 (HTLV-1) showed monoclonal growth of HTLV-1 infected T-cells. While the integration pattern of HTLV-1 was polyclonal in the peripheral blood mononuclear cells, it was monoclonal in the infiltrated cells of the pleural effusion. Morphologically atypical lymphoid cells were also found in the peripheral blood and in the pleural effusion. The pleural effusion disappeared after treatment with antituberculous drugs. The nature of the monoclonal proliferation of HTLV-1 infected T-lymphocytes is discussed.