In vivo Induction of Rabbit 2',5'-Oligoadenylate Synthetase.

By the study of in vivo induction of rabbit 2',5'-oligoadenylate synthetase (2',5'-OASE), it has been found that polyinosinic acid-polycytidylic acid (poly(I).poly(C)) can induce the formation of 2',5'-OASE only in rabbit peripheral blood mononuclear cells(PBMC), whereas New Castle disease virus (NDV) and erythropoietin (EPO) are capable of enhancing 2',5'-OASE level in the total red blood capsule (RBC) as well as in PBMC. It has been demonstrated that the enzyme is located in reticulocytes and that the increase of 2',5'-OASE level by phenylhydrazine, NDV, EPO in RBC is proportionally related to the increase of reticulocytes. The level of 2',5'-OASE in PBMC from rabbit treated with poly(I).poly(C), NDV, EPO is 6 times higher than that of the control, suggesting an induction effect occurs. Considering that poly(I).poly(C) and NDV are highly efficient inducers of rabbit interferon and that the induction kinetics by EPO is similar to that by interferon, it is reasonable to postulate that the induction effect of the two former agents are mediated by interferon, while the latter initiates induction directly.