Functional and ultrastructural studies of granulocyte adherence in the newborn.

Polymorphonuclear leukocyte (PMN) adherence to nylon was studied in the umbilical cord blood of 33 full-term, healthy newborns (NBs) during delivery. The results were compared to the adherence of PMN of peripheral blood in 50 healthy adult blood bank donors. PMN adherence in the NBs (56.64 +/- 3.24) was found to be significantly higher (p less than or equal to 0.01) than in the adults (47.03 +/- 2.01). PMN adherence, either in adults or NBs, is not related to leukocytes, platelets or hematocrit values. It was found to be related only to the percentage of total leukocyte adherence. Also using scanning electron microscopy (SEM), the ultrastructure of the adherence process was analyzed. In these studies we observed a higher tendency to adopt fusiform disposition in the PMN of the adult population. These results suggest that NB PMNs are hyperadherent and that they show a cellular rigidity and a resistance to deformation that could be responsible for the chemotactic alterations previously described in neonates.