An HTLV-I carrier who developed CD4+ T-CLL expressed the IL-2 receptor beta chain alone without expressing the alpha chain.

We describe a case of T-chronic lymphocytic leukaemia (T-CLL) with monoclonal proliferation of CD3+4+8- T cell expressing the interleukin 2 receptor (IL-2R) beta chain without expressing the alpha chain. Southern blot analysis of T-cell receptor beta chain gene revealed rearranged bands. The serum antibody was positive against human T-cell lymphotropic virus type I (HTLV-1)-associated antigens, but monoclonal integration of proviral DNA was not detected in the leukaemic cells. In accordance with the expression of IL-2R beta chain, the leukaemic cells proliferated in response to exogenous IL-2 without prior stimulation. However, culture supernatants of these cells did not show IL-2 activity. Since the role of the IL-2R beta chain in freshly isolated cells from T-CLL patients is not well understood, detailed analysis of this case would give us valuable information on the role of IL-2/IL-2R system in the proliferation of the leukaemic T cells.