Abstract
Serum immunoglobulin levels were measured with 144 domesticallybred cynomolgus monkeys, aged 0 day to 18 years. IgG level of the newborn just after birth was somewhat lower than that of their mother monkeys, continuing to decrease for 3 postnatal months. Thereafter, the level began to increase gradually till 4 to 5 years when an adult level was attained. IgA was detected on the day of birth in half of the animals and started to increase soon after birth, reaching an adult level in 5 to 6 years. A relatively low level of IgM was detected in all animals at birth. The increase of IgM level continued till 5 years of age. These patterns of immunoglobulin levels related to age are very similar to those of rhesus monkeys and human.
