Systems for Understanding the Immune System Role in Disease Processes

s of papers 3 7 Non-MHC alloantigen genes affecting immunity. W. E. Briles*, Northern Illinois University, DeKalb, IL 60115. An alloantigen is a genetically determined cell-surface molecule detected by specific antisera. An identifying letter has been assigned to each genetic locus responsible for the eleven distinct families of alloantigens A, C, D, E, H, I, J, K, L, P, and R. The genes of each system segregate independently of the other systems, except that the A and E are very closely linked (0.5% crossing over). Selection experiments over numerous generations have revealed distinct changes in gene frequency of the A-E alloantigens, suggesting immune responses associated with susceptibility to coccidiosis, antibody response to sheep red blood cells (SRBC), regression of Rous sarcomas, and selection for size of the bursa of Fabricius. Immune response effects of the C system of alloantigen genes are indicated by distinct gene frequency changes following selection for response to SRBC, selection for size of bursa of Fabricius, differential development of Rous sarcoma tumors, and macrophage nitrite production after LPS stimulation. Immune response effects of the D system of antigens are indicated by data from genetic selection for response to immunization with SRBC, selection for bursa size, and macrophage nitrite production following LPS stimulation. Immune response effects of the I system genes are indicated by distinct gene frequency changes in lines selected for bursa size, response to SRBC, selection for egg weight and within family comparisons for macrophage nitrite production. Effects of the L system, consisting of only two alleles, are indicated by the gene frequency changes following selection for bursa size, observed fertility effects, and direct comparison of genotypes within families for monocyte phagocytosis, IL-6 production, outcome of Rous sarcomas, and immune responses to SRBC and Brucella abortus. Genotypes of the P alloantigen system were directly compared within families of fully pedigreed chicks with significant differences for monocyte phagocytosis and macrophage nitrite production. Simultaneous segregation of eight systems in progeny of a single-cross are available to provide critical evaluation of immune response.