The effect of neonatal thymectomy on the level of salivary and serum immunoglobulins in rats.

The effect of neonatal thymectomy on the level of salivary and serum immunoglobulins was studied in conventional rats. Salivary SIgA levels were significantly decreased from weaning (day 20) through the termination of the experiment, while salivary IgG levels were generally unaffected by neonatal thymectomy. Serum IgA was detected at a later interval after birth in samples from thymectomized rats than from normal and sham-thymectomized rats and the levels of serum IgA in the thymectomized rats remained 4-5 times lower throughout the 115 day experimental period. Serum IgG was decreased by approximately 40% from days 28 through 115 after birth in the thymectomized animals, while serum IgM was apparently unaffected by the neonatal thymectomy. These findings indicate that the synthesis of salivary SIgA is markedly influenced by the presence of thymus-derived cells and it is suggested that these cells may control and/or modify immune responses in oral secretions.