Age of Appearance of IgG, IgM, and IgE Antibodies Specific for Loa loa in Gabonese Children

Abstract

IgG, IgM and IgE antibodies against the filaria L. loa were measured in umbilical cord blood and in blood from young Gabonese children by an ELISA [enzyme linked immunosorbent assay] technique using a homologous metabolic antigen. For children in 8 consecutive age groups and adults the percentage of the population positive for each of the antibody classes was determined. The number of children with maternal IgG decreased until 1 yr of age when new synthesis began to become apparent. IgM antibodies were detected only after 6 mo., probably indicating an early infancy as opposed to a fetal infection. The percentage of individuals positive for IgM or IgE reached a peak between 2 and 3 yr old, followed by a slight decline. Over half of the individuals over 1 yr of age had IgM antibody against L. loa, indicating long-term synthesis of this class of immunoglobulin in many people. In the first 2 yr of life, IgE antibodies were usually accompanied by L. loa-specific IgM. This specific IgE did not appear to trigger the synthesis of nonspecific IgE. By the age of 2, 95% of the population had some antibodies against L. loa and by 5 the percentage of individuals positive for each antibody class had reached adult levels.