Passive perinatal immunotherapy via transamniotic antibody delivery

We sought to determine whether the amniotic cavity/fluid could be an attainable route of administration of therapeutic antibodies to the fetus/neonate.

Time-dated pregnant dams (n = 9) received volume-matched intra-amniotic injections of either saline (n = 29), or different concentrations of a human IgG that lacked homology with rodents: 5 mg/mL (n = 28); 10 mg/mL (n = 28); or 15 mg/mL (n = 24). At term, the presence of the IgG was quantified by ELISA in the serum, bone marrow, spleen, thymus, and brain of all neonates, and in the maternal serum. Statistical analysis was by median regression with significance set at Bonferroni-adjusted p<0.008.

Overall fetal survival was 83% (90/109), with no difference between the groups. Human IgG was detected in the serum, bone marrow, spleen, thymus, and brain of all fetuses for all three injected concentrations, but not in the saline injected controls (p<0.001). A dose dependent relationship between injection concentration and final IgG load was noted in the bone marrow, spleen, and thymus (p = 0.004 to <0.001). Human IgG was also detected in maternal serum.

IgG antibodies can reach high levels in the fetal/neonatal circulation after simple intra-amniotic administration in a healthy rodent model. Transamniotic fetal immunotherapy (TRAFIT) may become a practicable strategy for the perinatal management of select diseases.

N/A (animal and laboratory study) TYPE OF STUDY: Animal and laboratory study.