TAT PROTEIN OF HIV-1 STIMULATES GROWTH OF CELLS DERIVED FROM KAPOSIS-SARCOMA LESIONS OF AIDS PATIENTS

KAPOSI'S sarcoma (KS) is frequently associated with human immunodeficiency virus-1 (HIV-1) infection1. Supernatants from HIV-1-infected T cells carrying the CD4 antigen promote the growth of cells derived from KS lesions of AIDS patients (AIDS-KS cells)2, and the HIV-1 tat gene, introduced into the germ line of mice, induces skin lesions closely resembling KS3. Here we report that the tat gene product (Tat) is released from both HIV-1-acutely infected H9 cells and tat-transfected COS-1 cells. These Tat-containing supernatants specifically promote growth of AIDS-KS cells which are inhibited by anti-Tat antibodies; recombinant Tat has the same growth-promoting properties. Therefore a viral regulatory gene product can be released as a biologically active protein and directly act as a growth stimulator. These and previous data3 indicate that extracellular Tat could be involved in the development or progression, or both, of KS in HIV-1-infected individuals. © 1990 Nature Publishing Group.