Inhibition of HIV-1 Infection by the β-Chemokine MDC

CD8$^+$ T lymphocytes from individuals infected with human immunodeficiency virus-type 1 (HIV-1) secrete a soluble activity that suppresses infection by HIV-1. A protein associated with this activity was purified from the culture supernatant of an immortalized CD8$^+$ T cell clone and identified as the β-chemokine macrophage-derived chemokine (MDC). MDC suppressed infection of CD8$^+$ cell-depleted peripheral blood mononuclear cells by primary non-syncytium-inducing and syncytium-inducing isolates of HIV-1 and the T cell line-adapted isolate HIV-1$_{IIIB}$. MDC was expressed in activated, but not resting, peripheral blood mononuclear cells and binds a receptor on activated primary T cells. These observations indicate that β-chemokines are responsible for a major proportion of HIV-1-specific suppressor activity produced by primary T cells.