Thymic function in NZB mice. I. Duration of thymic function in New Zealand Black (NZB) mice

Ageing 6–9-month-old NZB mice have been grafted with a syngeneic new-born thymus. Rapid normalization of the initially low level of circulating thymic factor (TF) and of responsiveness of spleen cells to phytohaemagglutinin (PHA) and concanavalin A (con A) was observed. However, this restoration was transient, both serum TF and mitogen responsiveness returning to the initially low levels within a month. These data support the idea that NZB mice present an early depression of thymus endocrine function, independent of anti-thymus antibodies and that recovery of mitogen responsiveness may be transient, directly dependent on serum TF level.