Identification of lymphocyte subsets in the newborn using a variety of monoclonal antibodies.

Using a small sample of peripheral venous blood, the normal range for lymphocyte subpopulations (T-cell, B-cell, T-suppressor cell, and T-helper cell) was defined in non-infected preterm and term infants. Lymphocyte subsets were identified using a variety of monoclonal antisera, and analysis was performed using a fluorescent activated cell sorter. Such methods allow an objective assessment of absolute numbers of cells per unit volume of whole blood. There was no significant difference in absolute numbers of lymphocyte subsets between term and preterm appropriate for gestational age (AGA) infants. Infants who were small for gestational age (SGA) had a significant deficiency in absolute numbers of total T-cells, helper and inducer T-lymphocytes, and B-cells compared with both term and preterm AGA infants. All newborn infants (term and preterm; AGA and SGA) had a highly significant increase in absolute numbers of both helper and suppressor T-lymphocytes compared with normal adults.