[Adult T-cell leukemia with Ki-1 expression].

A 64-year-old man was admitted to our hospital complaining of fever and edema in February, 1990. Lymph node biopsy revealed diffuse lymphoma pleomorphic type according to the LSG classification. On hematological examination, leukocyte count was 23,500/microliters, of which 36% abnormal lymphocytes expressing CD2, CD3, CD4 and CD25 as same as the lymph node cells. Anti-HTLV-I antibody in serum was positive. From these data, the diagnosis of adult T-cell leukemia (ATL) was made. ATL cells in the blood and lymph node expressed CD30 (Ki-1). CD30 positive ATL cells derived from the blood was increased after short-term culture. The induction of Ki-1 antigen in cell lines and short-term cultured cells from ATL patients was accompanied by the appearance of the HTLV-I related antigen. Then, we suggest that there was some relation between expression of the Ki-1 antigen and activation by HTLV-I in ATL cells.