Induction of Immune Suppression in the Chick by an Optimal Dose of an Immunizing Antigen in the Presence of its Specific Maternal Antibody

Prolonged interference 01 suppression of maternal antibodies of the humoral immune response of newly hatched chicks to active immunization has been documented, however, the immunological mechanisms responsible for such suppression are still unclear Lap nit hens were immunized with dinitrophenyl-keyhole limpet hemocyanin (DNP-KLH) Purified maternal anti-DNP or non-specific IgY antibodies were transferred by yolk sac inoculation 10 newly hatched chicks. and they were immunized with DNP-KLH or rabbit serum albumen (RSA) at I and 4 weeks of age The concentrations of anti-DNP and anti-RSA antibodies in serum samples of these chicks were measured using, an enzyme-linked immunosorbent assay (ELISA) The immune responses of the chicks that received a high close of maternal anti-DNP and were immunized with an appropriate close of DNP-KLH were suppressed However, those of the chicks that received the same high dose of maternal non-specific IgY antibodies and were immunized with an appropriate dose of DNP-KLH and those of the chicks that received a high dose of maternal anti-DNP antibodies and were immunized with RSA were not suppressed on the other hand, suppression of anti-DNP antibody production would not be induced if the chicks received a high close of antigen specific maternal antibodies and were immunized with a high dose of the same antigen These results revealed that the immune suppressive effect of maternal antibodies on the immune response of the newly hatched chicks was antigen specific and depended mainly on the ratio of antigen/maternal antibody at the time of immunization