Half-life of the maternal IgG1 allotype in infants

Abstract

The residence time of maternal IgG1 in the circulation of infants was measured by monitoring f-allotypic IgG1 or f-positive tetanus toxoid antibody in genetically G1mf-negative infants. G1ma-positive maternal tetanus toxoid antibody was similarly monitored in genetically a-negative infants. Blood samples were taken from infants at the age of 1-3 days, ca. 4 months, and ca. 6 months. An exponential decay at the same rate took place from age 1-3 days to 4 months and for the 2 subsequent months. The average concentration of the maternal IgG1 had dropped to ca. 10% of the 1- to 3-day value in 4 months and to ca. 3% in 6 months. The drop was due mainly to clearance but partly also to the weight increase of the child (doubling in 6 months). By correcting for the weight increase, we calculated that ca. 17 and 7% of the original maternal IgG1 was still present at ages 4 and 6 months, respectively. The average half-life of the maternal IgG1 was thus 48.4 days. The concentration of endogenous IgG1 in the cord blood was determined by studying a separate series of mother-newborn pairs. Assuming that cross-reactions of antiallotype reagents had no effect, the highest measured concentration of f-positive IgG1 in infants of f-negative mothers was 10 mg/L, half a percent of adult heterozygote values. Crossreaction may have played a role, however, and the value must be considered the upper limit of the true concentration.

Prevalence of Anti-Varicella-Zoster Virus Antibodies in French Infants under 15 Months of Age

“…This decline in the level of maternal antibody titers over the first months of life has already been documented for other infectious diseases (5,12,13). The half-life of anti-VZV antibodies calculated in our study (6 weeks) is in accordance with the results of a previous study reporting a half-life of 45 days for passively transferred anti-VZV IgG (21).…”

The EULAR points to consider for use of antirheumatic drugs before pregnancy, and during pregnancy and lactation

“…Treatment of the mother with IgG antibodies expressing high affinity to the fetal Fc receptor after gestational week 30 can lead to fetal/cord serum levels equal to or higher than maternal levels 61. IgG has a prolonged half-life, up to 48 days73 in the newborn; they typically disappear from the child’s serum within the first 6 months of life.…”

Maternal immunisation: collaborating with mother nature

“…for GBS ~60 days (29,134,135). T 1/2 of maternal antibodies of a given specificity can also 23 vary substantially between populations; whether this variability involves differences in IgG 1 subclass or other structural differences has not been delineated (136-138).…”