Fc gamma RI and Fc gamma RIII on polymorphonuclear leucocytes in cord blood.

Fc gamma RI and Fc gamma RIII expression on polymorphonuclear leucocytes in cord blood from seven normal infants was investigated by flow cytometry. Fc gamma R expression on fresh polymorphonuclear leucocytes in whole blood samples and in blood samples incubated with or without interferon gamma (IFN-gamma) for 48 hours was also studied. The percentage of Fc gamma RIII positive polymorphonuclear leucocytes in cord blood (73.3%) was significantly lower than that in adult controls (95.9%). The mean fluorescence intensity of Fc gamma RIII was significantly increased on cord polymorphonuclear leucocytes by the incubation with IFN-gamma. Fresh cord polymorphonuclear leucocytes expressed only a small amount of Fc gamma RI as adult polymorphonuclear leucocytes. The percentage of Fc gamma RI positive polymorphonuclear leucocytes induced with IFN-gamma was significantly higher in cord blood (62.3%) than in adult controls (30.3%). It is possible that decreased expression of Fc gamma RIII is a factor in the susceptibility of newborns to infection. High expression of Fc gamma RI stimulated with IFN-gamma in neonates could have a compensatory role against decreased immunological function.