Dengue Virus-induced Suppressor Factor Stimulates Production of Prostaglandin to Mediate Suppression

Abstract
Immunosuppression in dengue type 2 virus (DV)-infected mice is mediated through secretion of a soluble suppressor factor (SF) produced by T lymphocytes of the spleen. Activity of the suppressor cells was abrogated by pretreatment with indomethacin, indicating that suppression is mediated through prostaglandin (PG) or products of the PG synthetase pathway. The present study was undertaken to resolve the relationship between SF and PG. Treatment of mice with indomethacin did not affect production of SF. PG is different from SF and the presence of PG is not essential for its production. Normal mouse spleen cells treated in vitro with SF produced PG which mediated suppression. Production of PG by these cells was abolished by pretreatment with anti-Thy 1.2 antibody and complement. Immunosuppression apparently occurs in 2 phases: in the 1st step DV stimulates a subpopulation of T lymphocytes to produce SF and in the 2nd step SF induces a subpopulation of T lymphocytes to produce PG or products of the PG synthetase pathway which finally mediate suppression.