Antibody response to sheep red blood cells in a major histocompatibility (B) complex aneuploid line of chickens. Poultry Sci

is the production of antibodies specific for different antigenic challenges. Genes of the MHC encode products that regulate immunity. This study utilized the FCT-15 line of chickens, which is aneuploid for the chromosome containing the ribosomal RNA genes (rDNA) and the MHC or B complex to determine whether an antibody response to SRBC would vary as a function of B complex gene dose. Mating of trisomic parents (B15B15B15) animals produced progeny having either a disomic (B15B15), trisomic (B15B15B15), or tetra-somic (B^B^B^B15) B complex dosage. The number of B/rDNA chromosomes, and thus the B complex dosage, was determined by feather pulp nucleolar typing of chicks at hatch. A 5 % SRBC antigenic challenge, which induces a T cell-dependent antibody response, was injected at 6 wk of age. Samples taken prior to SRBC injection as well as 5, 8, and 12 d postinjection wer