Histocompatibility studies in a closely bred colony of dogs. 3. Genetic definition of the DL-A system of canine histocompatibility, with particular reference to the comparative immunogenicity of the major transplantable organs.

The segregation of the canine DL-A leukocyte group antigen(s) b, c, d, e, f, g, h, k, l, and m has been traced in 141 consecutive matings in the Cooperstown Colony of beagles. All of the leukocyte antigen(s) were regularly transmitted en bloc from parent to offspring, with no instance of independent segregation. A total of 23 haplotypes, including six different DL-A antigen patterns (gl, bkhfm, bkcd, e, be, fgl) was observed. 31 different DL-A phenotypes were observed in a population of 100 mongrel dogs. A number of statistically significant positive and negative associations between individual DL-A antigenic components occurred in this population. The results support the concept of the DL-A system as a complex immunogenetic system governed by a single region (or locus) of an autosomal pair of chromosomes. Studies of skin, kidney, heart, and liver allografts in the Cooperstown Colony indicated that the longest allograft survivals occur under genetically and serologically defined conditions of donor-recipient DL-A compatibility. Skin and renal allografts generally behaved in parallel fashion, while cardiac allografts survived for longer periods of time (MST = 47.1 days) than kidneys (MST = 28.1 days) or skin (MST = 25.1 days) under conditions of DL-A identity. Heart transplants were rejected at a more rapid rate than kidney, however, in DL-A-incompatible donor-recipient combinations. Liver transplants were accorded the longest survival time (MST = 76.2 days) under conditions of DL-A identity, but were rejected at a rapid rate (MST = 5 days) in DL-A-incompatible nonlittermate donor-recipient pairs. The results provide further evidence that the DL-A system is the principal system of histocompatibility in the canine species. The differences in survival of different organs under similar conditions of donor-recipient DL-A compatibility suggest, however, the existence of a number of unknown variables which may also be capable of significantly affecting allograft behavior.

Histocompatibility studies in a closely bred colony of dogs. I. Influence of leukocyte group antigens upon renal allograft survival in the unmodified host.

The establishment of a closely bred colony of beagles with known leukocyte group phenotypes has permitted an assessment of the role of leukocyte group antigens in conditioning the survival of renal allografts in the unmodified host. 22 kidney transplants obtained from leukocyte group-compatible donors were accorded a mean survival time of 25.5 days, as compared with 13.1 days for 27 transplants obtained from incompatible donors. Donor-recipient coefficients of correlation and Swisher erythrocyte group incompatibilities did not appear to affect the observed results. The mean survival time of 21 renal allografts performed in randomly selected mongrel dogs was 9.5 days. Availability of a carefully characterized and phenotyped canine population may be useful in further studies of the comparative immunogenicity of the major transplantable organs, and of methods designed to facilitate prolonged organ transplant survival in the mammalian host.

Histocompatibility studies in a closely bred colony of dogs.

17 Cooperstown beagles of known DL-A genotypes were exposed to supralethal total body irradiation and received a bone marrow allograft from a DL-A-identical donor; 11 littermate and 6 nonlittermate donor-recipient pairs were studied. The recipients are surviving uneventfully for 315, 364, 424, 440, 531, 531, 584, 605, 625, 635, and 649 days in the littermate group and for 211, 279, 280, 368, 479, and 480 days in the nonlittermate group. The radiation chimeras underwent bilateral nephrectomy and received a kidney allograft obtained from their respective marrow donor within 43-120 days after bone marrow transplantation. The renal allografts are surviving for 191, 200, 221, 234, 313, 349, 361, 377, 378, 405, 441, 444, 482, 557, 580, 581, and 586 days, respectively. 12 of 13 skin allografts obtained from the marrow donor are at present surviving in the recipients for 107, 110, 110, 110, 116, 122, 128, 143, 143, 162, 178, and 199 days, respectively; one graft was rejected at 84 days. In contrast, the radiation chimeras rejected 25 skin allografts obtained from DL-A-incompatible donors within 10.5-21 days (MST = 15.2 days). Skin transplants obtained from DL-A-identical siblings of the bone marrow donors were rejected within 20-36 days (MST = 25.8 days) in recipients of bone marrow cells obtained from littermate donors. Recipients of nonlittermate bone marrow transplants accorded such allografts a prolonged survival time of 27-76 days (MST = 56.2 days). Prospective selection of genotypically DL-A-identical donor-recipient pairs results in the regularly reproducible long-term survival of bone marrow allografts. The radiation chimeras produced in this manner have developed a donor-specific state of unresponsiveness to kidney and skin allografts. The results are consistent with the existence in the canine species of at least three closely linked genetic systems relevant to transplantation, including DL-A, MLC, and a possible bone marrow transplantation locus.

Histocompatibility studies in a closely bred colony of dogs. V. Mechanisms of cellular adaptation in long-term DL-A identical radiation chimeras.

20 Cooperstown beagles of known DL-A genotypes (B" dogs) were exposed to supralethal total body irradiation and received a bone marrow allograft from a DL-A identical donor (A" dog); the resulting chimeras have survived uneventfully for 882, 1466 days, with no evidence of secondary disease, and have been tolerant to kidney and skin allografts obtained from the donor of marrow. Treatment of "A" dogs with serum obtained from their long-term "B" chimeras had no significant effect upon the ability of the recipients to reject "B" skin allografts...

Histocompatibility studies in a closely bred colony of dogs. II. Influence of the DL-A system of canine histocompatibility upon the survival of cardiac allografts.

The DL-A system of histocompatibility plays an important role in conditioning the survival of cardiac allografts in the unmodified canine host. The mean survival time of six cardiac allografts performed in DL-A-compatible littermate dogs obtained from a closely bred colony of beagles was 53.2 days, while the MST of transplants performed in seven DL-A-incompatible animals was 7.3 days. The MST of cardiac allografts performed in nine DL-A-compatible nonlittermate beagles was 26.3 days, as compared with 6.3 days in six DL-A-incompatible nonlittermate transplants. The results did not appear to be affected by Swisher erythrocyte-group incompatibilities. The MST of 28 cardiac allografts performed in randomly selected mongrel dogs was 10.0 days. Incompatibilities for DL-A antigens e, f, g, l, and m may constitute major barriers to transplantation, but antigens b, c, d, and k appeared to act as weak histocompatibility antigens. Under controlled conditions of donor-recipient DL-A compatibility, cardiac allografts may be less immunogenic than renal transplants. Heart transplants performed across major donor-recipient DL-A incompatibilities appeared, however, to be more vulnerable to the events of allograft rejection than renal allografts performed under similar conditions. The selection of optimally compatible donor-recipient combinations for organ transplantation may be aided materially by genetic studies of the transmission of DL-A antigens to the animals under consideration.

Induction of allogeneic unresponsiveness in adult dogs. Role of non-DLA histocompatibility variables in conditioning the outcome of bone marrow, kidney, and skin transplantation in radiation chimeras.

Exposure to supralethal total body irradiation and transplantation of bone marrow from a DLA- and pedigree-identical donor have regularly produced successful engraftment and the establishment of stable long-term chimerism in beagles of the Cooperstown colony. Bone marrow allografts performed in pairs of dogs bearing identical DLA haplotypes derived from different pedigree origins (i.e., different classes of the same haplotype) yielded two different results. Depending upon the particular haplotype pedigree combination used, such transplants either led to long-term chimerism or to failures of engraftment, secondary disease, and death of the recipients (i.e., pedigree-incompatible combinations). Radiation chimeras given bone marrow from a DLA-and pedigree-identical donor were challenged within 8-12 h after marrow transplantation with a renal allograft obtained from another DLA- and pedigree-identical donor. The recipients have remained unresponsive to such renal allografts and have survived indefinitely with normal renal function. In contrast, renal allografts obtained from donors bearing the same DLA haplotypes derived from pedigree-incompatible sources were rejected within 25-50 days after transplantation. The long-term surviving recipients have also been unresponsive to skin allografts obtained from their donor of marrow and the kidney donor. Skin grafts obtained from other DLA- and pedigree-identical dogs were rejected within 13-41 days, and grafts from DLA-incompatible donors survived for 10-25 days. These results highlight the potential importance of genetically controlled histocompatibility determinants other than DLA in conditioning allograft reactivity. The determinants uncovered in the present study appear to be linked to the DLA complex, as demonstrated by the ability of the pedigree origins of DLA haplotypes present in individual dogs to serve as an effective marker system for such non-DLA antigen(s). The results also point to the potential usefulness of the early postirradiation period for the induction of allogeneic unresponsiveness in large adult mammals.

Allogeneic unresponsiveness to orthotopic cardiac transplants in DL-A-identical radiation chimeras.

Nine Cooperstown beagles of known DL-A genotypes were exposed to supralethal total-body irradiation and received bone-marrow allografts from DL-A-identical donors. Four to 5 months later, the resulting chimeras received orthotopic cardiac allografts from their corresponding donors of marrow. Six chimeras died of operative complications in the immediate postoperative period. The other 3 chimeras survived from 173 to 547 days; 1 dog died at 173 days as a result of right-sided heart failure, secondary to stenosis at the site of the pulmonary artery anastomosis. The other two recipients continue to be active and healthy at 545 and 547 days. The results indicate that dogs can be rendered specifically tolerant to orthotopic cardiac allografts by supralethal total-body irradiation and the transplantation of marrow obtained from the prospective allograft donor.