ABSTRACT
The most immature infants have critically low concentrations of all immunoglobulin
G (IgG) subclasses, associated with a higher risk for pyogenic, respiratory, and meningeal
infection. Selective IgG subclass deficiency is an established indication for intravenous
immunoglobulin (IVIG) substitution. However, considering that therapeutic efficacy
of IVIG is dependent on its pharmacokinetics, we studied peak and trough IgG subclass
serum levels during the neonatal period (28 days) in a group of 34 healthy preterm
babies (30.2 ± 2 weeks gestational age (GA) and 1065 ± 210 g birthweight (BW) treated
prophylactically with three daily standard doses of two different IVIG preparations:
Sandoglobulin (SG) (0.5 g/kg/day) and Pentaglobin (PG) (5 mL/kg/day). IgG subclass
levels were assayed by radioimmundiffusion (RID) before treatment (day 1) and at days
3, 5, 7,14, and 28 of life. Statistical analysis was performed by paired t test. In the first week of life only (days 3, 5, 7), for both IVIG preparations,
subclass levels were higher than pretreatment values: lgG1, 4.6 ± 1.7 versus 5.6 ±
1.6 g/L; lgG2, 1.6 ± 0.8 versus 2.1 ± 0.6 g/L; lgG3, 0.2 ± 0.7 versus 0.3 ± 0.1 g/L;
lgG4, 0.3 ± 0.1 versus 0.9 ± 0.1 g/L (p < 0.05). During this time (7 days) lgG2 levels were higher in the SG group and lgG4
was higher in the PG group (p < 0.05). This study shows pretreatment IgG subclass levels 14 days after treatment
and different patterns, depending on the used preparation. We conclude that prospective
clinical trials should include the study of target serum levels and timing of IVIG
administration not only for IgG but also for IgG subclasses.
Keywords
Intravenous immunoglobulin (IVIG) - premature infants - immunoglobulin subclass concentration
