Detection of maternal DNA in placental/umbilical cord blood by locus-specific amplification of the noninherited maternal HLA gene.

A critical issue regarding the broader utilization of placental/ umbilical cord blood (PCB) in unrelated bone marrow restoration is the possibility of contamination with maternal lymphocytes capable of immunological reactivity against the eventual recipient. On transplantation, such maternal cells might lead to graft-versus-host disease (GVHD) even if the intended donor's neonatal lymphocytes were unresponsive. We measured the proportion of PCB samples that were contaminated with maternal cells. Placental-maternal sample pairs were selected so that the mother was heterozygous for the DR53 haplotype, whereas the placental sample was DR53-negative. The PCB samples were investigated for the presence of the noninherited maternal gene DRB4, exclusive to the DR53 haplotypes. Locus-specific polymerase chain reaction amplification with DRB4 sequence-specific primers was followed by either gel electrophoresis or blotting and hybridization to an internal sequence DRB4 probe. Polymerase chain reaction products from DNA mixtures containing as low as 0.5 ng of a DRB4-positive DNA control in 1.0 microgram of a DRB4-negative DNA sample (1:2 x 10(3) dilution) showed a visible DRB4 band in agarose gels stained with ethidium bromide. Locus-specific hybridization increased the detection sensitivity to 1:10(5) (0.01 ng of the DRB4-positive DNA control). Control mixtures of known amounts of DRB4-positive and -negative DNA were included in all experiments. Comparison of the thickness of DRB4 bands after electrophoresis and the intensity of the DRB4-specific hybridization signals to the concentration controls allowed a rough estimation of the amount of maternal DNA in the placental blood specimens. A total of 213 PCB samples were tested. By gel electrophoresis, DRB4-specific bands were observed to be as strong or stronger in 23 (10.8%) samples as those in the 1:2 x 10(3) control, and 153 (17.8%) samples were negative in this test. The remaining 37 (17.3%) samples disclosed weaker DRB4 bands, suggesting the presence of maternal genetic material. By hybridization, 81 (38%) samples were positive and 132 were negative for the noninherited maternal gene. Review of the clinical characteristics of the mothers (demographics and labor and delivery information), the newborns (birth weight, sex, and gestational age), and PCB collections (placental weight, white blood cell count, and collected volume) failed to show any significant differences between the units testing positive or negative for the noninherited maternal gene. Thus, transplantable PCB units carry a high probability of having maternal DNA in detectable amounts. Whether this DNA comes from potentially graft-versus-host disease-inducing maternal lymphocytes or whether the putatively transplacentally-acquired maternal cells are immunologically dysfunctional, as in most infants with severe combined immunodeficiency disease, remains to be shown.

No excess of DR*3/4 in Ashkenazi Jewish or Hispanic IDDM patients.

The gene frequencies, haplotype relative risks, and zygotic assortments of HLA-DR in three ethnically defined samples of insulin-dependent diabetes mellitus (IDDM) patients were determined in a prospective family study. Although DR3 and DR4 were positively associated with IDDM in the probands of 123 northern European, 94 Ashkenazi Jewish, and 49 New York Hispanic families, significant excess of DR*3/4 heterozygotes was observed only among the probands from families of northern European ancestry. There was also a significant decrease in the frequency of Bw62,DR4 haplotypes derived by northern European patients from their mothers compared with their fathers. This difference, together with data reported in the literature, suggests that the expressivity of the susceptible genotype(s) in IDDM patients may be modified by protective maternal effects associated with Bw62,DR4 and probably other DR4 haplotypes. Samples of IDDM patients from populations with high frequencies of these modifiers should have different DR-gene frequencies contributed by fathers and mothers, capable of accounting for the observed Hardy-Weinberg disequilibrium. We postulate that, because the mechanism of action of these modifiers is distinct from that of the susceptibility gene, the difference must be considered in devising strategies for elucidation of the mode of inheritance of the disease and for understanding the molecular nature of the susceptibility.

DQA1 restriction fragment length polymorphisms and insulin-dependent diabetes mellitus: a BglII fragment labels a subset of B8,DR3 haplotypes uniquely associated with insulin-dependent diabetes mellitus.

Class II restriction fragment length polymorphism studies of 38 pedigrees with multiple cases of insulin-dependent diabetes mellitus revealed the existence of a DQA1-related polymorphism that distinguishes two kinds of HLA-B8,DR3 haplotypes. One of these, characterized by the presence of DQA1-BglII 7.20 kb, was present in all 14 examples inherited by patients and in 6 of the 12 B8,DR3 haplotypes not so inherited. The apparently complete association between the presence of this fragment and the "affected" status of B8,DR3 haplotypes (p = 0.004) was confirmed in a separate group of 26 simplex pedigrees selected for the presence of this haplotype in the respective probands (combined p less than 0.0001).

RFrAP: a computer program for analysis of complex HLA RFLPs. Assignment of restriction fragments to haplotypes by segregation analysis.

The availability of HLA class II cDNA probes has led to the development of a powerful method for the discrimination of genetic variation in this region of the major histocompatibility complex. There are problems with this approach which reduce its usefulness, including the hybridization of a probe with multiple restriction fragments (RFs) from the same locus or of two different cDNA probes with the same RF (cross-hybridizing). These problems may now be largely overcome by the relatively simple computer program presented here, which allows the entry, storage, and editing of phenotype data. It includes utilities for the automatic assignment of bands to haplotypes and also statistical functions to determine several types of correlations. The outputs are presented in a format familiar to HLA serologists and immunogeneticists. In addition, the data is stored in a manner that allows the user to easily prepare "ad hoc" figures and tables that illustrate the more complex relationships among bands and between them and other variables.

Definition of IDDM-associated HLA DQ and DX RFLPs by segregation analysis of multiplex sibships.

Genetic variation of the DQ alpha and beta and of the DX alpha genes, detectable as RFLP in genomic DNA digests, has been suggested to improve the identification of individuals at high risk for insulin-dependent diabetes mellitus (IDDM). DNA from all members of 32 IDDM multiplex families was digested with six restriction endonucleases and the resulting fragments analyzed in Southern blots for hybridization with labeled cDNA probes for those genes. A computerized segregation analysis procedure was then used to assign fragments to haplotypes. Associations among fragments and between fragments and haplotypes characterized serologically and biochemically for their class II genes and IDDM-carrier status were calculated. The results indicate that the alleles of the DX alpha polymorphism maintain linkage disequilibrium with those of the DQ beta genes responsible for the well-known DQ beta 3.2-IDDM association, so that IDDM-carrier haplotypes carry disproportionally often both DQ beta 3.2 and DX alpha-TaqI-2.2kb. Thus, these RFLPs identify a DR-DQ-DX haplotype in high linkage disequilibrium, rather than the locus or loci that account for their high relative risk. However, four DR4-DQ beta 3.2 haplotypes that lack DX alpha-TaqI-2.2kb were encountered, two of which are "affected." These haplotypes suggest that the identification of the "disease locus" can be facilitated by the study of unusual haplotypes in which distinct IDDM-associated alleles occur separated from their neighbors of the standard genetic configurations.

Molecular characterization by high-resolution isoelectric focusing of the products encoded by the class II region loci of the major histocompatibility complex in humans. I. DR and DQ gene variants.

We describe a new approach to the analysis of the structural polymorphism of the DR beta, DQ alpha, and DQ beta polypeptide chains of human histocompatibility class II antigens. In comparison to conventional two-dimensional gel studies, this method provides sharper definition of the protein bands and side-by-side comparisons within the same gel, thereby permitting the detection of minor differences in the isoelectric points of the protein chains. Using this methodology we have analyzed the IEF polymorphism and the variability in the number of the DR beta chains encoded by different DR haplotypes. Twenty DR beta chain variants, which include the products of no less than two separate DR beta loci, have been thus far identified. Alleles at one of these loci are assumed to code for DR beta chains carrying the DR alloespecificities DR1, DR2, DR3, DR4, DR5, DRw6, DR7, and DR8. Alleles at a second DR beta locus encode DR beta chains that may be shared by serologically DR-different haplotypes and carry supertypic serologic specificities (i.e., DRw52 and DRw53). We also demonstrate here that the structural polymorphisms of the DQ alpha and DQ beta chains are more extensive than previously thought, report the characterization of 14 DQ beta variants, and define their relationship to the previously described DQw serologic specificities. In addition, we describe the class II haplotype associations observed for the different DR and DQ variants characterized.

Induction of unresponsiveness to major transplantable organs in adult mammals: a recapitulation of ontogeny by irradiation and bone marrow replacement.

Transplantation of renal allografts obtained from prospectively selected genotypically DLA-identical donors into supralethally irradiated dogs reconstituted with their own stored bone marrow has produced a state of unresponsiveness to these kidneys in the recipients. Eleven of 18 kidneys transplanted at 12 hours after marrow replacement currently survive with normal function and maintain life in the recipients for 757, 800, 825, 978, 1062, 1092, 1136, 1282, 1373, 1380, and 1381 days, respectively. Similar results occurred in eight of 13 allografts transplanted at 28 hours after marrow replacement, which currently survive for 349, 363, 377, 407,436,470, 485, and 513 days, respectively, and in eight of 13 kidneys grafted at 36 hours after marrow replacement, which are surviving for 197, 247, 298, 324, 337, 396, 443, and 472 days, respectively. Achievement of optimal results is dependent on the specific timing and sequence of each procedure. Only four of 16 recipients of kidneys transplanted at the time of marrow replacement were unresponsive to their allografts. Similarly, only five of 19 recipients of kidneys placed in irradiated dogs at 40 hours before marrow replacement accepted such allografts. When kidney transplants were placed into the recipients 20 hours before removal of marrow, irradiation, and reconstitution with stored marrow, only three of 21 dogs became unresponsive to such ailografts. In five of 12 instances, the recipients were also unresponsive to skin allografts obtained from their respective kidney donors. Such skin grafts currently survive for 606, 673, 687, 701, and 708 days, respectively. The remaining seven skin grafts were rejected at 28, 39,42, 84, 90, 92, and 115 days, respectively. Second- and third-set skin grafts from the same kidney donor were rejected by six of these dogs at 19, 20, 21, 29, 29, and 30 days, and at 21, 22, 23, 24, 27, and 27 days, respectively. Rejection of these skin grafts had no detectable effect on the function and survival of kidney allografts from the same source. Seven of eight skin grafts obtained from other DLA-identical donors were rejected at 13,14,16,25,28,38, and 84 days, respectively; one allograft continues to survive for 708 days. Eleven DLA-incompatible skin allografts placed on the recipients at the same time were rejected within 11-20 days. Supralethal total body irradiation and bone marrow replacement can establish in the adult canine host a privileged phase of immunological reactivity during which exposure to alloantigens produces specific long-term unresponsiveness rather than sensitization. The use of stored autologous rather than allogeneic bone marrow for reconstitution of the irradiated recipient eliminates the hazards of GVH complication usually associated with this procedure. This consideration and the apparent capacity of the tolerant host to maintain a long-term state of unresponsiveness without any further immunosuppressive therapy point to the potential relevance of the results to human transplantation.

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.

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.

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.