Adult T-cell leukemia with anti-HTLV-I antibody but no HTLV-I DNA in tumorcells

Adult T-cell leukemia (ATL) is usually defined as a malignant disease of T cells infected by human T-lymphotropic virus type I (HTLV-I). In the presen t study, we describe a 49-year-old woman with an acute type ATL, whose leuk emic cells do not contain the HTLV-I genome. Laboratory tests revealed an i ncrease in abnormal lymphocytes with convoluted nuclei, elevated serum lact ate dehydrogenase levels, increased thymidine kinase activity and soluble i nterleukin-2 receptor-alpha levels. Serum examination demonstrated positive anti-HTLV-l antibody, but Southern blot analysis using the whole HTLV-I ge nome as a probe did not detect any integration of the viral genome. In cont rast, PCR detected the HTLV-I pX region in the sa me DNA samples as used fo r Southern blot analysis. These findings suggest two possibilities. One pos sibility is that ATL in this patient is generated by other pathogens than H TLV-I virus. She is also an HTLV-I carrier. The other possibility is that h er leukemic T cell clone derived its malignant phenotype from HTLV-I infect ion, and once this malignant phenotype was obtained, partial deletions of v iral genome repeated until the whole viral genome was deleted. Although the re is no direct evidence, the former possibility is more likely in the pres ent case. Copyright (C) 2001 S. Karger AG, Basel.