Thymic function in NZB mice. II. Regulatory influence of a circulating thymic factor on antibody production against polyvinylpyrrolidone in NZB mice.

Administration of a circulating thymic factor isolated from normal pig blood prevented the development of the exaggerated production of anti-polyvinyl pyrrolidone (PVP) antibody in young NZB mice. However, treatment was ineffective if initiated after the 4th week of life at a time when endogenous serum thymic factor (TF) normally disappears in these mice. These data suggest that circulating TF is necessary for the survival of short-lived suppressor T cells normally implicated in the regulation of the production of antibodies against PVP, a thymus-independent antigen. In older NZB mice, TF treatment increased paradoxically anti-PVP antibody production, which suggests that "amplifier" T cell activity could also be under TF influence.