Erythrocyte membrane sialic acid in new-born infants.

Erythrocyte surface sialic acid was measured in 94 full-term new-born infants and in 20 premature infants of different ages, varying from 1 to 16 post-natal days. After the first 3 days of life, the amount of sialic acid, both per cell and per gramme of haemoglobin, was rapidly reduced to 70-80% of the initial value; these lower levels were maintained on the following days. The decrease observed on the 4th day may represent an expression of the mechanism by which a large amount of fetal red blood cells is eliminated from the circulation during the same period. Therefore, the relationship between sialic acid decrement and red cell sequestration exists also in fetal erythrocytes, and this may contribute to clarify the exact role of sialic acid in red cell survival time.