Abstract
Three fractions of Nocardia, Nocardia water-soluble mitogen (NWSM), Nocardia water-soluble mitogen pellet (NWSMP), and the cell wall peptidoglycan, which are mitogenic for B lymphocytes, were able to induce circulating interferon in mice, NWSMP and NWSM being the most active. The peak of interferon appeared about 2 h after injection. The interferon induced by NSWMP and NWSM was acid stable and antigenically related to viral interferon, as shown by neutralization with antibodies directed against Newcastle disease virus-induced interferon.