In vivo role of macrophages in transmission of dengue virus-induced suppressor signal to T lymphocytes

Abstract

Dengue type 2 virus (DV)-induced suppressor T cells (Ts1) produce a soluble suppressor factor (SF) which stimulates a subpopulation of T lymphocytes (Ts2) to produce prostaglandin which suppresses DV-specific IgM antibody plaque forming cells (PFC) in vivo and in vitro. The present study was undertaken to investigate the intermediary role of macrophages in transmission of signal from Ts1 to Ts2. The SF is adsorbed on live or heat-killed mouse peritoneal macrophages and transmits DV-specific PFC in spleen after i.p. or i.v. inoculation in DV-primed mice. The suppression is antigen-specific. SF or SF-adsorbed heat-killed macrophages failed to transmit suppression in silica-treated macrophage-depleted mice when injected i.p., while SF-adsorbed live macrophages could transmit suppression. In macrophage-depleted mice suppression could be transmitted by SF-adsorbed heat-killed macrophages on i.v. inoculation. It was therefore concluded that live macrophage-killed cells are also essential for transmission of suppressor signal by SF from Ts1 to Ts2 in vivo.