The role of dendritic cells in the regulation of T cell cytokine synthesis

Cytokine regulation of HIV replication induced by dendritic cell-CD4-positive T cell interactions

It has been established that human immunodeficiency virus (HIV) replication occurs throughout the course of disease in the lymphoid tissue. We have developed a model system to study the effect of cytokines and other agents on HIV replication using cocultures of DCs and T cells that reflect the cell-to-cell interactions that occur in the microenvironment of lymphoid tissue. Dendritic cells from peripheral blood, when pulsed with small amounts of HIV, induce infection in autologous, unstimulated CD4-positive T cells. Using this system, cytokines, anti-cytokine antibodies, and inhibitors of cellular activation were added to cultures and the effects on cellular proliferation and activation and HIV production were measured. Cytokines that increased T cell proliferation, such as IL-2 and IL-4, enhanced HIV replication, while the effect of IL-12 was more complex. HIV production was inhibited by blocking endogenously produced IL-2, as well as by adding IL-10, which blocks IL-2 secretion, antigen-presenting cell function, and T cell activation. Proinflammatory cytokines induced modest enhancement of viral replication in cocultures of HIV-pulsed DCs and CD4-positive T cells. Thus, using a model of HIV replication that more closely mimics the in vivo microenvironment of lymphoid tissue may allow a better analysis of the effect of cytokines and cytokine networks, as well as agents that modify immune activation on HIV replication.