CHICKEN MHC ALLOANTISERUM CROSS-REACTIVITY ANALYSIS BY HEMAGGLUTINATION AND FLOW-CYTOMETRY

The major histocompatibility complex (Mhc) haplotype in the chicken is generally determined by the use of alloantisera in a hemagglutination assay. This method restricts haplotype determination to antigens expr essed on the surface of erythrocytes which includes class I (B-F) and class IV (B-G) antigens as well as any other polymorphic molecules on these cells. Alloantisera can result in complex cross-reactivity patte rns. We describe here the analysis of 53 alloantisera made within Mhc- congenic lines. Each antiserum was tested by hemagglutination with ery throcytes and by flow cytometry with erythrocytes and peripheral white blood cells of seven Mhc haplotypes; B-2, B-5, B-12, B-13, B-15, B-19 , and B-21. Five types of antiserum were identified based on their rea ctivity to different cell subpopulations of the peripheral blood of th e donor haplotype as well as in cross-reactivity for different haploty pes. RBC specific cross-reactive antigens attributed to B-G molecules were demonstrated for the B5:B19, B12:B19, and B19:B21 cross-reactions . Cross-reactive antigens detected on RBC and thrombocytes attributabl e to B-G molecules on both types of cells were demonstrated for the B2 :B12, B2:B15, B2:B19, and B2:B21 cross-reactions. In addition, cross-r eactive antigens occurring on RBC and WBC were attributed to B-F (or R BC and lymphocyte-expressed B-G loci) and included the B12:B13, B13:B1 9, and B15:B19 cross-reactions. Several antisera with specificity for B cells purportedly identifying B-L epitopes were found but their numb ers were limited and cross-reactivities were not defined. The identiti es described here may be useful in understanding B haplotype similarit ies and differences in disease resistance and immune response.