Delayed-type hypersensitivity response to KLH in F2 and backcrosses of two immune selected chicken lines: effect of immunisation and selection.

Cell-mediated immune response to keyhole limpet hemocyanin (KLH) was studied in 13 different progeny groups belonging to a second generation cross between two lines of White Leghorn previously selected for 10 generations for high antibody response to Newcastle disease vaccine (ND3) and high cell-mediated response to phytohemagglutinin (PHA) measured as wing web swelling. The cutaneous hypersensitivity response to KLH was assessed in KLH immunized and non-immunized birds. Wing thickness was measured at three time points: before the injection and 4 and 24 hours after the injection. The effect of previous immunization and genetic background was assessed. While no differences were present between progeny types or to a randomly bred control line at any of the three time points, significant differences were present between immunized and not immunized birds 24 hours after challenge. Results demonstrate that KLH immunized birds perform better and that the previous selection and crossbreeding scheme has not influenced the intensity of the skin swelling response to KLH. Apparently, neither selection for antibody responsiveness to ND3 nor selection for enhanced responsiveness to a T cell mitogen affected delayed-type hypersensitivity (DTH) to the Th 2 antigen KLH. These results may serve to facilitate further selection based on independent immune parameters.