Quantitative Study of Thymocytes Injected into Young. Rats born to Azathioprine-administered Pregnant Rats

Abstract

The plaque assay was performed to determine the optimal dosage of thymus cells to be inoculated into the neonatally T-cell depleted rats by azathioprine for the recovery of immune function. The experimental animals were two hundred young rats which were born to sixty normal Sprague-Dawley pregnant rats, of which 45 rats had 8 mg/kg of azathioprine orally administered to them on the 7th day of the gestation. Sheep erythrocytes (sRBC) antigen was intraperitioneally injected into the animals on the 4th & 8th weeks after birth and simultaneously the thymus cells derived from outbred Sprague-Dawley rats were inoculated into 4 experimental groups with the dosages of 105 , 106 , 107 and 108 thymus cells, respectively. The spleens were resected on the 3rd & 7th days after sRBC injection for the plaque assay. The following results were obtained. 1. In the neonatally T-cell depleted group, there was statistically significant decrease in the number of PFC, compared with that in the control group. 2. In the 4 week old groups, the normal level of PFC could be reached by the inoculation of between 106 and 107 thymus cells, in 8 week old groups, by the inoculation of between 105 & 106 thymus cells. 3. In both 4 week old and 8 week old groups, the peak numbers of PFC were obtained by the inoculation of 107 thymus cells.