Spontaneous regression associated with apoptosis in a patient with acute-type adult T-cell leukemia

We describe a 76-year-old man with acute-type adult T-cell leukemia, who demonstrated a spontaneous decrease in leukemic cell number, apparently coincident with apoptotic cell death. On admission the patient's white blood cell count was 38.9 x 10(9)/l with 77% abnormal lymphocytes. He also had hypoproteinemia (4.3 g/dl) from protein losing enteropathy. After admission the leukemic cell count decreased without chemotherapy, reaching 5.9 x 10(9)/l after 2 months. Studies of peripheral lymphocytes demonstrated appearance of the apoptotic cells and DNA ladder formation from the beginning of regression. Same truncated proviral DNA was recognized in primary ATL cells through the whole clinical course. The hypoproteinemia improved with intravenous nutrition, followed by increase of the leukemic cells. This case is the first report that demonstrates tumor-cell apoptosis induced clinical regression in adult T-cell leukemia. Further, we speculate that the hypoproteinemia may have been involved in the leukemic cell apoptosis.