A widely used drug that suppresses cellular immunity inhibits prostaglandin and leukotriene synthesis and increases the catabolism of IgG antibody is :
Glucocorticoids are powerful immunosuppressants. These inhibit both cellular and humoral immunity by:

Decreasing the recruitment of immune cells.
Catabolism of immunoglobulins.
Inhibiting the enzyme phospholipase A2 resulting in decreased production of PGs, LTs and TXs.
Cyclophosphamide
Prednisone
Cyclosporine
Infliximab