Serum levels of IgG subclasses in critically ill premature infants treated with intravenous immunoglobulins

: Fifty eight premature infants, all needing intensive care and mechanical ventilation, were randomly allocated to two groups. Intravenous immunoglobulins (IVIG, 500 mg/kg Sandoglobulin) were administered to Group 1 while Group 2 received saline as placebo. IgG subclass serum levels were evaluated in both groups on admission, after two hours from the end of IVIG or saline infusion and from day 3 to 7 from birth. IgG subclasses were also measured in 10 healthy term neonates during the first day of life. Results show that after 2 hours from the end of IVIG administration all IgG subclasses reach levels comparable to term neonates. Comparing IgG values between treated and untreated preterm neonates it was observed that on day 3 only IgG1 and IgG3 subclasses were significantly higher in Group 1 than in Group 2. At day 5 no differences were observed between the two groups. IgG2 subclass rose reaching a significant difference between the two groups ad day 5 and 7. Our data show that IVIG single dose (500 mg/kg) administration doesn't produce a constant elevation in all IgG subclasses during the first week of life in the critically ill preterm infant.