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.
Karaca
M
M
Department of Animal Science, Iowa State University, Ames 50011-3150, USA.
Johnson
E
E
Lamont
S J
SJ
D000818:Animals; D000906:Antibodies / Q000097:blood; D000941:Antigens / Q000276:immunology*; D000942:Antigens, Bacterial / Q000276:immunology; D002003:Brucella abortus / Q000276:immunology; D002645:Chickens / Q000235:genetics* / Q000276:immunology*; D004912:Erythrocytes / Q000276:immunology; D006239:Haplotypes; D007700:Kinetics; D008285:Major Histocompatibility Complex; D012756:Sheep; D013601:T-Lymphocytes / Q000276:immunology*
D000906:Antibodies; D000941:Antigens; D000942:Antigens, Bacterial