Lack of effect of thymectomy on spontaneous recovery from tolerance to levan

Abstract
Adult CBA mice were made tolerant with 1 mg levan and tested subsequently for spontaneous recovery by plaque-forming cell assay in response to immunizing challenge. Weakening of tolerance was first detectable only after 100 days, while return to full normal responsiveness required 400 days. Thymectomy 2 weeks prior to tolerization neither retarded nor diminished the recovery process. Loss of tolerance which had been induced by 1 mg dextran B512 was much slower in onset (> 250 days), yet not delayed by thymectomy (full recovery was not followed). These findings in relation to other considerations imply that associative recognition by T cells is not required for B cell responses to these “thymus-independent” antigens.