Virus production and spontaneous cell proliferation in HTLV-I-infected lymphocytes

Cultured peripheral blood lymphocytes (PBL) from HTLV-I-infected individuals proliferate in the absence of added mitogens and/or cytokines. In an attempt to answer questions regarding the activating signals for cells and virus, antibodies that react with cell surface components that are known to regulate cell activation and antibodies reacting with viral proteins were added to cultures of PBL from HTLV-I-infected, disease-free individuals. Spontaneous proliferation and virus production increased in the presence of antibodies reacting with CD3 and alpha/beta T cell receptors (TCR) while antibodies to HLA class II and viral proteins had no effect. Addition of HLA class I antibodies shut down virus production and cell proliferation. These observations indicate that both virus and cell activation may occur through the alpha/beta TCR on the infected cell. Cyclosporin A, however, markedly decreased cell proliferation but had only a modest suppressive effect on virus production. Thus, the uncoupling of cell proliferation from virus production by cyclosporin A suggests the possibility that the signal transduction pathways for these two events are different.