Phenindione is an anticoagulant which functions as a Vitamin K antagonist. Target: Others Phenindione(Rectadione) is an anticoagulant which functions as a Vitamin K antagonist. A lymphocyte transformation test showed proliferation of T-cells from the hypersensitive patient, but not from four controls on exposure to phenindione in vitro. Drug-specific T-cell clones were generated and characterized in terms of their phenotype, functionality, and mechanism of antigen presentation. Forty-three human leukocyte antigen class II restricted CD4+ αβ T-cell clones were identified. T-cell activation resulted in the secretion of interferon-γ and interleukin-5