Development of lymphoid hyperplasia in transgenic mice expressing the HIV tat gene.

During HIV infection, individuals experience multiorgan disorders such as adenopathy, splenomegaly, and lung and brain diseases. There is an increasing body of evidence that the HIV trans-activating tat gene product possesses multiple activities. First, it can activate several cellular genes; second, in its extracellular soluble form, it plays the role of growth factor in some cells such as Kaposi's sarcoma cells. Thus, we introduced the HIV tat gene, under the control of the cellular proteolipoprotein promoter, into the germline of mice and demonstrate that, when expressed, the tat gene product induces lymphoid hyperplasia in spleen, lymph nodes, and lung, as is observed in AIDS patients, but not in the brain or testes. Our findings indicate that HIV, through some of its genes, directly participates in the pathogenesis of AIDS.