Anti-human T-cell lymphotrophic virus type I antibody-positive adult T-cell leukemia/lymphoma with no monoclonal proviral DNA. A clinicopathologic and immunologic study.

Proviral DNA of adult T-cell leukemia virus (HTLV-I) was examined by the standard Southern blotting method in lymph nodes of 45 patients with anti-HTLV-I antibody (ATLA)-positive adult T-cell leukemia/lymphoma (ATLL). Six of these patients revealed no monoclonal proviral HTLV-I DNA in tumor cells. These six patients showed typical flower cells in peripheral blood; they comprised five cases of the smoldering type and one of lymphoma type. They showed a longer clinical course than ATLL patients with integrated proviral HTLV-I DNA. Five of the six patients were alive from 8 to 36 months after onset; the other patient died 9 months after onset. Histologically, they exhibited features of T-cell malignancy but with absence of the typical cerebriform giant cells that are usually present in ATLL. The tumor cells represented T-cell markers, usually CD4, but CD25 was negative. Rearrangement of the T-cell receptor gene C beta was found in four of the six cases. On the basis of these results, cases of ATLL with no monoclonal proviral HTLV-I DNA should be clinicopathologically differentiated from those with integrated proviral DNA.