1. Foetal rhesus monkeys (at 10–16 weeks gestation) were treated in utero with bovine serum albumin (BSA) and subsequently, as neonates, were tested for immunity or tolerance. 2. Five out of six monkeys treated in utero with 100 mg BSA were tolerant to BSA at challenge. 3. Some foetuses responded to treatment with 1–8 mg BSA in adjuvant with formation of antibody. 4. One monkey treated with a total of 350 mg BSA during the first 3 weeks after birth was tolerant to BSA at challenge; two other neonatal monkeys treated with 100 mg BSA did not show tolerance. |