Nonimmune rosette formation: a measure of the newborn infant's cellular immune response.

Nonimmune rosette formation, an in vitro measure of cellular immunity, was evaluated in normal newborn infants. Active rosette formation in 14 specimens of cord blood was 18.9 +/- 4.8% compared to 28.1 +/- 5.2% in 15 adult control samples (p less than 0.05). Total rosette formation in 13 cord blood samples was 33.3 +/- 7.6% compared to 55.1 +/- 6.5% in 15 adult control specimens (p less than 0.05). Tritiated thymidine uptake from phytohemagglutinin stimulation was comparable in cord blood and adult control lymphocytes. The importance of these findings is discussed in light of other recent reports suggesting that cord blood thymic derived T lymphocytes may have reduced immune capability when compared to adult lymphocytes.