Genetic line and major histocompatibility complex effects on primary and secondary antibody responses to T-dependent and T-independent antigens
The effects of MHC and nonMHC (background) genetics on the kinetics of primary and secondary antibody responses to T-cell-dependent (SRBC) and T-cell-independent [Brucella abortus (BA)] antigens were investigated. Eight genetic groups were represented, with four homozygous MHC haplotypes [B1-IrGATlow (IrGAT = immune response to GAT locus); B1-IrGAThigh; B19-Ir-GATlow; B19-IrGAThigh] on two genetic backgrounds, the S1 and G lines. Birds were injected simultaneously with BA and SRBC at 4 and 7 wk of age, and blood samples were taken weekly from 4 to 10 wk of age for measurement of total agglutinating serum antibody levels. A quadratic equation and its first derivative were computed for each bird to approximate individual curve parameters: y max, the maximum titer; t max, the time required to achieve y max; and c coefficient, the rate of decline in the titer. Curve parameters of birds from different lines were analyzed separately by using the General Linear Model procedure. A second analysis that included line effect evaluated the nonMHC gene effects and their interactions with erythrocyte antigen B locus (Ea-B) or IrGAT. In the S1 line, there was an interaction (P < 0.05) between MHC haplotypes and sex for primary response to BA. In contrast, there were no significant main effects nor interactions in the G line background for primary and secondary responses to BA and SRBC. There was an effect (P < 0.05) of line background on y max for primary BA and for secondary SRBC responses. A positive correlation (P < 0.05) was found between the c coefficients of BA and SRBC secondary responses, suggesting that the rate of decline in the secondary response is similar between these T-dependent and T-independent responses. The overall results of this study indicate complex interactions between specific MHC alleles and the nonMHC background of the lines in which they are studied.
This article is published as Karaca, M., E. Johnson, and S. J. Lamont. "Genetic line and major histocompatibility complex effects on primary and secondary antibody responses to T-dependent and T-independent antigens." Poultry Science 78, no. 11 (1999): 1518-1525. DOI: 10.1093/ps/78.11.1518. Posted with permission.