PROBLEM TO BE SOLVED: To provide a pharmaceutical composition useful for a treatment or prevention of immune diseases related to helper T cell (CD4T cell).SOLUTION: Disclosed are a pharmaceutical composition for a treatment or prevention of Th1 immune disease comprising an anti-CD155 antibody (inhibition antibody) inhibiting a binding of a ligand to a CD155 which regulates Th1 immune response toward positive in vivo resulting in regulating Th2 immune response toward negative, thereby being associated with exacerbations of Th1 immune disease and suppressions of Th2 type immune disease or a pharmaceutical composition for a treatment and prevention of Th2 immune disease comprising an anti-CD155 antibody (agonist antibody) having an agonistic effect which activates a CD155.
