Human blood lymphocyte subpopulations from birth to eight years.

Total lymphocyte counts and the number of SmIg positive and E-rosetting cells in the blood of 103 healthy Brazilian children between birth and eight years and fifty-one healthy adults were compared. A high number of total lymphocytes were observed during the first year of life and decreased thereafter to reach adult values by the age of seven years. The proportion of SmIg positive cells was high in the newborn, further increased during the second trimester and remained unchanged up to the end of the first year of life. Thereafter they gradually decreased reaching adult levels by the age of three years. The percentage of E-rosetting cells was low in the newborn and young children and increased after the second year of life to reach adult levels by the age of seven years. The absolute number of both lymphocyte subpopulations changes with approximately the same pattern as the total lymphocyte counts.