A. W. Nordskog

Relationship of Blood Type to Histocompatibility in Chickens

Evidence shows that the B blood group locus in chickens, which controls red cell antigens, is associated with tolerance of skin homografts. Three other blood group loci studied did not show this effect.

Nomenclature for chicken major histocompatibility (B) complex.

1 Department of Biological Sciences, Northern Illinois University, DeKalb, Illinois 60115 z Houghton Poultry Research Station, Huntingdon, Cambs PE17 2DA, United Kingdom 3 The Wistar Institute, Thirty-Sixth Street at Spruce, Philadelphia, Pennsylvania 19104 4 Department of Microbiology, New York University School of Medicine, 550 First Avenue, New York, New York 10016 5 College de France, Laboratoire de M6dicine Exp6rimentale, 11, Place Marcelin-Berthelot, 75231 Paris, Cedex 05, France 6 Institute for General and Experimental Pathology, University of Innsbruck, Fritz-Pregl-Strasse 3, A-6020 Innsbruck, Austria 7 Institute for Experimental Immunology, University of Copenhagen, N0rre Alle 71, DK-2100 Copenhagen 0, Denmark s Department of Immunology and MRC Group of Immunoregulation, University of Alberta, Edmonton, Alberta, Canada 9 Department of Animal Science, Iowa State University, Ames, Iowa 50011 10 Basel Institute for Immunology, Grenzacherstrasse 487, CH-4005 Basel, Switzerland ~1 Department of Avian Medicine, College of Veterinary Medicine, University of Georgia, Athens, Georgia 30605 a Department of Medical Microbiology, Turku University, Turku, Finland 20520

Recombination between genes coding for immune response and the serologically determined antigens in the chickenB system

Evidence is presented for a crossover between the genes coding for the serologically determined (SD) antigens on erythrocytes and an immune response gene (Ir-GAT) controlling immune response to the synthetic polypeptide GAT within theB complex, the MHC of chickens. TheIr-GAT1 andIr-GAT19 alleles control low and high immune response to GAT, respectively. Both low and high responders were recovered as recombinants fromB1B1 andB19B19 birds. The low-responder haplotypes are homozygous for theIr-GAT1 allele and the high-responder haplotypes carry theIr-GAT19 allele. Mortality forB1B1 nonresponder birds was 39%, compared with 19% for theB1B1 high responders; this suggests the possibility that genes located within the immune response region of theB complex exert some genetic control over viability and survival.

Genetic linkage between immune response to GAT and the fate of RSV-induced tumors in chickens

Recent studies suggest that the gene locus controlling the fate of tumors induced by Rous sarcoma virus (RSV) is linked to theB histocompatibility complex. Birds carrying the dominant allele regress the tumor; homozygous recessives being unable to do so, develop large tumors and die. These are called progressors.The Bryan strain of RSV was inoculated into 220 6 week old Leghorns homozygous forB1B1,B2B2, orB19B19 of which the percentages of progressors were 79, 22 and 56, respectively. The balance of each were regressors and survived.TheB1B1 test birds were derived from special matings, i.e., high and low immune responders to the amino acid polymer, GAT. Of 67 tests progeny of theB1B1 GAT-low mating, 63 or 94% proved to be progressors, and 6% were regressors. Of 84 test progeny of theB1B1 GAT-high matings, 67% were progressors, and 33% were regressors. The difference between the high and low GAT responders is highly significant and indicates that the locus controlling the fate of RSV-induced tumors is closely linked to the locus controlling immune response to GAT. The latter maps within theIr region of theB histocompatibility complex.

Relationship of Erythrocyte to Leukocyte Antigens in Chickens

Tests with blood typing antisera revealed that antigens of the A, D, and L blood group systems are erythrocyte specific, while antigens of the B and C systems are common to lymphocytes and erythrocytes. Injection of day-old chicks with erythrocytes inhibited production of agglutinins for lymphocytes as well as erythrocytes when subsequent immunizations were attempted.

GENETIC CONTROL OF SERUM IMMUNOGLOBULIN G LEVELS IN THE CHICKEN

Serum IgG (7S) levels differed significantly for chickens from 10 different inbred lines. Within lines differences between B blood groups were statistically significant.

B-COMPLEX GENETIC CONTROL OF IMMUNE RESPONSE TO HSA, (T,G)-A–L, GT AND OTHER SUBSTANCES IN CHICKENS

Immune response to poly‐(l‐tyrosine‐l‐glutamic acid)‐poly‐d, l‐alanine‐poly‐l‐lysine ((T,G)‐A–L), human serum albumin (HSA), and (l‐glutamic acid50, l‐tyrosine50)n (GT) was found to be linked to the B complex in an outbred line of Leghorns segregating for the B1, B2, and B19 alleles. Birds of the blood group genotypes B1B1, B2B2, and B19B19 were low, intermediate, and high responders, respectively to either (T,G)‐A–L or HSA. Response to GT, however, differed, with the B2B2 genotype being the only responder. No real genotype differences in immune response to DNP‐conjugates and sheep red blood cells (SRBC) could be detected.

Immune response and adult mortality associated with the B locus in chickens.

We are studying immune response to natural and synthetic antigens as related to viability and disease and are attempting to determine the extent to which the major histocompatibility complex (the B blood group system) is involved. We are using a noninbred line, SI, segregating for 3 B alleles and 7 inbred lines with inbreeding coefficients ranging from 60–97%. This gives us the opportunity to compare the experimental efficiency of inbreds and noninbreds for studies of immune response. A unique feature of our approach concerns the B1B1 genotype. In particular, B1B1 chickens show consistently high adult mortality, 4- or 5-fold higher than controls, and they are highly susceptible to Marek’s disease virus. Also, they have proved to be low responders to Salmonella pullorum bacterin, human serum albumin, GAT10, and (T, G)-A—L. We think that there is some broad immunodeficiency associated with BIBI but as yet we have not discovered it.

GENETIC LINKAGE OF SUBGROUP C ROUS SARCOMA VIRUS‐INDUCED TUMOR EXPRESSION IN CHICKENS TO THE IR‐GAT LOCUS OF THE B COMPLEX

Two B complex genotypes, B1B1 and B19B19, of outbred line S1, were tested for low and high immune response to GAT, from which four recombinants were recovered: B1B1 GAT‐hi and lo, and B19B19 GAT‐hi and ‐lo. Also included in the study were birds of B2B2 genotype with an intermediate level of immune response to GAT.A total of 225 birds of these groups were challenged with the Bryan strain of Rous Sarcoma virus subgroup C, RSV (RAV‐7), by inoculation into the wing web at five weeks of age. The B1B1 genotype had the lowest percentage of regressors (17.6%), B19B19 had the highest (42.2%), and the B2B2 genotype was intermediate (23.7%). Combining the results of GAT response over the B1B1 and B19B19 genotypes, 14.0% of GAT‐lo and 37.8% of GAT‐hi regressed their tumours, respectively. The highly significant (P ≤ 0.01) difference between the combined GAT‐hi and ‐lo groups would suggest that the Rs locus controlling tumour regression induced by the subgroup C virus is closely linked to the region controlling immune response to GAT, but the data also provides evidence that the B‐F region of the B complex also plays an important role in RSV‐induced tumour regression.

Role of the immune-response region of the B complex in the control of the graft-vs-host reaction in chickens

The relative importance of the B and IR regions of the chicken B complex were compared as to their role in the graft-versus-host (GVH) reaction. Spleen enlargement (splenomegaly) on 19-day-old embryos, inoculated 5 days earlier with immune competent leukocytes, served as the test for the GVH reaction. The B blood group locus was the marker of the “B” region, and the Ir-GAT gene was the marker of the immune response (Ir) region of the B complex, the major histocompatibility system (MHS) of chickens. The test stocks consisted of B1B1 GAT-Low (1-Low) and B19B19 Gat-High (19-High) birds of our S1 Leghorn line plus the recombinant genotypes B1B1 Gat-High (1-High) and B19B19 GAT-low (19-Low). A dosage of 0.1 ml of donor white blood cells was injected into each of 191 recipient embryos on day 14, and the spleens were removed and weighed on day 19. Of 16 combinations of (donor blood)-(host embryos), arranged with respect to the four genotypes listed above, four were compatible, e. g., (1-Low)-(1-Low). There were four incompatible combinations at the B locus, four at the GAT locus, and four at both the B and GAT loci. All 16 combinations were replicated. Results were expressed as a splenomegaly index (SI), that is, the ratio of incompatible to compatible spleen weights corrected for differences in embryo weight. If (SI-1) is greater than 0, the GVH reaction is considered positive within sampling errors. The mean (SI-1) indexes obtained were: incompatible at GAT-0.5±0.07; incompatible at B-1.34±0.10. Thus, both GAT and B contributed to the GVH reaction, but the B region was much stronger than the IR region. The results were strongly asymmetrical: maximal stimulation occurred when the host embryo was B19B19 GAT-high and donor leukocytes were B1B1 GAT-Low. The parental donor-host paired combinations gave stronger GVH reactions than did the recombinant pairs. Effects of incompatibilities at the two regions proved additive when compared with two-locus differences of parental genotypes. In general, the results proved that the IR region, as specifically defined by recombinants obtained in our S1 line of Leghorns, plays a significant, but minor, role in the GVH reaction compared with the region of the B complex identified with the B blood-group locus.