Transmission of dengue virus-specific suppressor signal depends on the presence of calcium.

The present study was undertaken to investigate the role of calcium in the production of dengue type 2 virus (DV) induced suppressor cytokine (SF) and in transmission of the suppressor signal via syngeneic macrophage (M phi) to recruit the second subpopulation of suppressor T(TS2) cell. Effect of calcium channel blocking drugs, Verapamil and Nifedipine, on the production and activity of SF was investigated. The production of SF was inhibited in a dose dependent manner by the calcium channel blockers. The suppressor activity of SF was also inhibited by calcium channel blocking drugs. SF could not be produced when spleen cells were cultured in a calcium free medium, the production being restored on substitution with calcium chloride. Treatment of M phi with the calcium channel blockers inhibited the transmission of the suppressor signal from TS1 to TS2 cells in a dose dependent manner. The influx of calcium during transmission of the suppressor signal was studied by measuring the 45Ca uptake. Calcium channel blocking drugs inhibited the 45Ca uptake by T lymphocytes. Thus, presence of calcium is obligatory for the production and suppressor activity of SF and it plays a critical role in transmission of the suppressor signal.