[Immunodepressive activity of phenobarbital chemically bound to the protein carrier]

Experiments conducted on mice immunized with sheep's erythrocytes proved that phenobarbital, even in toxic doses does not produce any immunodepressive effect. But when it is covalently bound by the diazo-method with a protein-carrier phenobarbital becomes a strong immunodepressant. Then, however, it does not affect the central nervous system, nor influence the immunodepressive activity of cyclophosphamide--an agent metabolically activated in the liver. Free phenobarbital mitigates the effect of cyclophosphamide on the immunological response in mice.