Effect of lipid A on neonatal and adult red blood cell deformation

Lipid A is responsible for the endotoxic activities of gram-negative bacteria. Red blood cell (RBC) deformation was studied in adults, in full-term and preterrn infants during 60 min of in vitro incubation with lipid A (100 μg/ml) using a rheoscope. Compared to control values without lipid A incubation, RBC deformation (shear stress of 4 Pa) in adults, preterm, and from full-term neonates were decreased after 15 min (11%, 10%, 8%, respectively), after 30 min (11%, 6%, 3%, respectively) and after 60 min (8%, 5%, 2%, respectively) of incubation with lipid A. The decrease in RBC deformation after 15 min was significant (p<0.05) in the four groups. After 30 and 60 min, RBC deformation in the neonates recovered to the control values. In adults, RBC deformation improved after 30 and 60 min but did not reach preincubation values. These results indicate that neonatal RBC deformability recovers more rapidly than adult RBC during lipid A incubation.