Human alloimmune sera against T cell subsets. Detection and influence on pokeweed mitogen-stimulated Ig production in vitro.

Sera from multiparous women contain antibodies against T cell subsets. Population and family studies of four anti-T cell-subset antibodies are given. Two of these reacted with part of the suppressor T cell fraction (T gamma) and two with part of the helper T cell fraction (T mu) cells. By mixing T gamma- and mu-enriched cell suspensions in different concentrations, preliminary evidence was obtained that the anti-T cell-subset sera recognized T cells that had different functions in pokeweed mitogen-stimulated cytoplasmic immunoglobulin synthesis.

Major histocompatibility complex-restricted antibody reactivity mainly, but not exclusively, directed against cells from male donors.

An IgM antibody, present in the serum of a female patient with aplastic anemia, is described that reacted in a modified complement-dependent cytotoxicity test with a subset of the B cells from HLA-A2-positive, but not HLA-A2-negative males. With the exception of two HLA-A2 positive females, the antibody did not react with other cells from either HLA-A2-positive or HLA-2-negative females. The cells of one of these and from HLA-A2-positive males were able to absorb the antibody from the serum. Cells from other donors were unable to absorb the antibodies. The mononuclear cells of the same patient were cytolytic in cell-mediated lympholysis (CML) for phytohemagglutinin blasts from all HLA-A2-positive males and one of the females reacting with antibody, but not with blasts from HLA-A2-negative males and all other females. Thus, the results obtained with the antibody in the complement-dependent cytotoxicity test showed an almost perfect correlation with cytolysis in CML tests. These results suggest that the IgM antibody may be the first example with major histocompatibility complex restriction. Because the antibody reacted with the cells from two female donors, the restricting determinant is not, in all probability, the H-Y determinant.

Human hematopoietic progenitor cells in long-term cultures express HLA-DR antigens and lack HLA-DQ antigens.

The expression of HLA-DR antigenic determinants on human hematopoietic progenitor cells (HPC) capable of differentiating into mature blood cells, as determined in semisolid cultures, has been demonstrated previously (3-7). Here, we investigated the expression of class II determinants on HPC responsible for the sustained proliferation of colony-forming units of granulocyte/macrophage (CFU-GM), of multilineage HPC (CFU-GEMM, granulocyte/erythrocyte/macrophage/megakaryocyte), and burst-forming units of erythroid cells (BFU-E) in liquid long-term cultures. Using both fluorescence-activated cell sorting and complement-dependent cytotoxicity assays, HLA-DR determinants could be identified on virtually all these HPC capable of proliferating in long-term cultures. Experiments in which the stromal layer had been irradiated provided evidence that the HPC themselves were truly HLA-DR+, and that the sustained proliferation of HPC was not due to activation of HLA-DR- residual HPC in the stromal layer by reinoculated HLA-DR+ accessory cells. Furthermore, it was shown that all HPC recognized in semisolid and liquid long-term cultures were HLA-DQ-. These results suggest that the human true pluripotential stem cell is HLA-DR+. These results open the possibility of studying class II-dependent regulation of hematopoiesis in liquid long-term cultures.

Consequent intrafamilial immunization for DL-A haplotyping in canines.

A procedure of intrafamilial immunization is described for production of antisera recognizing DL-A haplotypes. In a colony consisting of 1 sire, 6 bitches, and 67 offspring all haplotypes could be accurately allocated. In the colony the observed reaction frequencies of the antisera are in agreement with mendelian codominant inheritance. Mixed lymphocyte culture tests confirmed the accuracy of the serologic typing and the presence of homozygous individuals within the colony. Further evidence is presented supporting the presence of two or more subloci within the DL-A system. Colonies of canines such as the one described should provide a sensitive system for evaluating interaction between serologic DL-A typing, MLC reactivity, and immune response genetics in a nonrodent species which is not highly inbred.

Major histocompatibility complex-restricted H-Y-specific antibodies and cytotoxic T lymphocytes may recognize different self determinants.

Previous studies have shown that influenza virus-immune cytotoxic T lymphocytes can recognize virus in conjunction with self HLA-A2 antigens. Nevertheless, the virus-infected target cells from one HLA-A2-positive male donor (designated M7) could not be lysed by the virus-immune cytotoxic lymphocytes from any HLA-A2-matched unrelated donors. Although extensive serological analyses showed no difference between the HLA-A2 antigens of donor M7 and other HLA-A2-positive donors, isoelectric focusing of the HLA-A2 molecule from donor M7 revealed a clear difference in the heavy polypeptide chains when compared with the HLA-A2 molecules of other donors. The present study demonstrates that the HLA-A2-restricted anti-H-Y cytotoxic T lymphocytes obtained from a female aplastic anaemia patient fail to lyse the male M7 target cells, whereas the HLA-A2-restricted anti-H-Y antibodies from the same patient react with the cells of donor M7. These results suggest that: (a) HLA-A2-restricted anti-H-Y antibodies can recognize self determinants on the HLA-A2 molecule that are distinct from those that are recognized by HLA-A2-restricted anti-H-Y cytotoxic T cells; and (b) HLA-restricted T and B cells may use different receptor repertoires for the recognition of foreign antigens such as H-Y.

Genetic aspects of canine mixed leukocyte cultures.

Recent data stress the importance of matching donor and recipient of an organ graft for both the serologically defined (SD) and lymphocyte-defined (LD) determinants. To allow experimental evaluation of the effect of these SD and LD structures in a noninbred experimental animal, mixed leukocyte culture tests were performed between SD identical and nonidentical dogs to clarify the LD system in these animals. The results of these experiments can be summarized as follows: (a) In the dog there is a LD locus distinct from the known SD loci, which in all probability is localized outside the first (SD-1) series locus on the chromosome. (b) The crossing-over frequency between the SD and LD loci on the chromosome is low. (c) Studies in SD identical unrelated dogs and random unrelated dogs show an apparent high linkage disequilibrium between SD and LD loci. (d) The LD system in dogs is polymorphic.

Cellularly defined minor histocompatibility antigens are differentially expressed on human hematopoietic progenitor cells.

Previously, five CTL lines directed against minor histocompatibility (mH) antigens designated HA-1-5 have been established from peripheral blood of patients after allogeneic bone marrow transplantation (BMT), and have been characterized using population and family studies. All cell lines showed specific HLA class I-restricted lysis of PHA-stimulated peripheral blood target cells from donors positive for the particular mH antigens. After 4 h of incubation of the mH antigen HA-3-specific CTL line with bone marrow cells from HA-3+ donors, complete class I-restricted inhibition of colony growth of the hematopoietic progenitor cells was observed even at low E/T ratios, indicating that the HA-3 antigen is strongly expressed on hematopoietic stem cells. Therefore, this antigen may be a target structure in the immune-mediated rejection of the hematopoietic graft in case of incompatibility for this determinant between donor and recipient in allogeneic BMT. In contrast, incubation of bone marrow cells with the antigen-specific anti-HA-1, -2, -4, and -5 CTL lines did not result in growth inhibition of the hematopoietic progenitor cells tested. After a prolonged incubation time and using a very high E/T ratio, progenitor cells from HA-2+ or HA-5+ donors were killed to some extent by the anti-mH-specific CTL lines, although the growth inhibition observed was minor and variable. Our results show that mH antigens are differentially expressed on human hematopoietic progenitor cells. Therefore, only some of these antigens may be targets in immune-mediated rejection of the bone marrow graft.

HLA-DO polymorphism associated with resistance to type I diabetes detected with monoclonal antibodies, isoelectric point differences, and restriction fragment length polymorphism.

A new HLA-DQ-related genetic system with two alleles, 2B3 and TA10, defined serologically by MAbs and alloantisera, showed an almost perfect correlation with charge differences on DQ beta molecules, as well as with two polymorphic DNA fragments hybridizing with a DQ beta probe and various restriction enzymes on a panel of 14 DR4+ homozygous typing cells. It was therefore concluded that the serologically defined alleles 2B3 and TA10 are coded by the DQ beta gene and situated on the HLA-DQ beta chain. This 2B3/TA10 polymorphism is independent of HLA-D and segregates with HLA in families. The TA10 allele appears to be a new marker for resistance to type I diabetes, which is independent from the known resistance marker DR2, whereas no association was observed between this DQ beta polymorphism and rheumatoid arthritis.

Minor histocompatibility antigen-specific cytotoxic T cell lines, capable of lysing human hematopoietic progenitor cells, can be generated in vitro by stimulation with HLA-identical bone marrow cells.

Recipient-antidonor alloreactivity before HLA genotypically identical bone marrow transplantation (BMT) between donor-recipient pairs that are negative in the mixed lymphocyte reaction (MLR), the cell-mediated lympholysis (CML) assay, and the lymphocyte crossmatch was not detectable in the majority of cases, using recipient peripheral blood lymphocytes (PBL) collected before BMT as responder cells and donor PBL as stimulator cells. However, when donor bone marrow mononuclear cells (BMMNC) instead of PBL were used as stimulator cells, we could detect donor-specific alloreactivity in 7 of 10 HLA genotypically identical donor-recipient pairs. To demonstrate that this alloreactivity was minor histocompatibility (mH) antigen specific and not directed against HLA class I splits or variants, two cytotoxic T lymphocyte (CTL) lines were tested in further detail against phytohemagglutinin (PHA) blasts from pairs of HLA genotypically identical siblings positive for the HLA class I restriction molecule. Both CTL lines recognized mH antigens, as illustrated by the differential recognition of PHA blasts of one of the two siblings from several pairs. The potential role of these mH antigen-specific CTLs in bone marrow graft rejection was demonstrated by the mH antigen-specific growth inhibition of hematopoietic progenitor cells from the original bone marrow donor and from HLA class I restriction molecule-positive individuals who expressed the mH antigens on their PBL and BMMNC. Our assay can be used in HLA genotypically identical BMT to detect a recipient-antidonor response, directed against cellularly defined mH antigens expressed on donor HPC, BMMNC, and PBL, before transplantation.

The influence of allogeneic cells on the human T and B cell repertoire.

Clinical transplantation is often complicated by rejection episodes, in which the immune system of the recipient reacts to the foreign transplantation (HLA) antigens on the graft. This immune response includes humoral and cellular components. In the first, B lymphocytes form antibodies to the HLA alloantigens. In the second, CD8+ T lymphocytes recognize and react to HLA class I antigens, and CD4+ T cells react to HLA class II antigens. The frequency and severity of these rejection episodes can be diminished by immunosuppressive drugs, HLA matching between donor and recipient, and immune modulation by blood transfusion. Effective HLA matching between donor and recipient is not always possible and often not necessary. Insight into the factors that influence the T and B cell repertoire after blood transfusion might lead to new approaches to improve graft survival.

Induction of B cell unresponsiveness to noninherited maternal HLA antigens during fetal life.

Patients who have received many transfusions become highly sensitized and develop antibodies against almost all HLA alloantigens, so that finding a cross-match negative kidney donor is difficult. A survey of those patients showed that 50 percent did not form antibodies against the noninherited maternal HLA antigens. Apart from the obvious clinical implications, the data indicate that a human equivalent of murine neonatal or actively acquired tolerance has now been identified.

Eleven million donors in Bone Marrow Donors Worldwide! Time for reassessment?

On 16 November 2005, we celebrated the milestone when 10 million donors had been registered in Bone Marrow Donors Worldwide (BMDW). Since then another million donors have been added in little more than a year. It seems an appropriate time for reassessment and to ask whether we are on the right track or not. We will do so by discussing the strength, weaknesses, opportunities and threats of the unrelated stem cell donor operation.

Analysis of HLA-D micropolymorphism by a simple procedure: RNA oligonucleotide hybridization.

Recent progress in the molecular genetics of HLA class II antigens has revealed the existence of multiple loci and of a large degree of polymorphism, with more individual alleles than was expected. An accurate detection and analysis of this extensive polymorphism is essential for optimal HLA typing for transplantation and for a reevaluation of HLA-disease association. Because of the limitations of the current typing methods, including restriction fragment length polymorphisms, we have proposed a DNA typing procedure based on hybridization with loci- and allele-specific oligonucleotides. Here we present a much simpler way of analyzing class II micropolymorphism down to the level of single nucleotide differences. RNA oligonucleotide typing (ROT) relies on RNA dot blots and requires 10-20 ml of blood. It is shown that with appropriate oligonucleotide probes, ROT can reliably and unambiguously identify any polymorphism at any of the HLA loci, including new alleles, not identified with previous methods. This illustrates the importance of oligonucleotide typing to optimize HLA matching, in particular for transplantation involving unrelated donors.

Highly diverged MHC class I mismatches are acceptable for haematopoietic stem cell transplantation.

A fully major histocompatilbility complex (MHC) matched donor is not available for the majority of patients in need of a haematopoietic stem cell transplantation (SCT), which illustrates the need for a tool to define acceptable MHC disparities. Previously, we noticed that a variety of single MHC class I mismatched allogeneic donor-recipient pairs did not elicit an allogeneic cytotoxic-lymphocyte (CTL) response in vitro if the MHC amino-acid sequences had five or more differences in the alpha-helices plus five or more differences in the beta-sheet (> or =5alpha5beta) (7). To address the clinical relevance of this observation, we analysed CTL precursor (CTLp) assay outcome and SCT outcome in 53 Dutch recipients of a single MHC class I mismatched graft from an unrelated donor. Overall patient survival was 44% after 4 years. In multivariate analysis, recipients of a > or =5alpha5beta mismatched graft with negative CTLp frequencies in vitro before transplantation demonstrated superior survival: survival at 4 years was 80% as compared to 47% in recipients of other mismatched grafts with negative CTLp frequencies (hazard ratio=0.131; 95% CI=(0.03-0.61); P=0.009). This option of acceptable mismatches may enlarge the pool of potentially acceptable stem cell donors.

Molecular identification of the TCA alloantigen as the transferrin receptor on T-cells of a leukemic patient with serum from a monozygotic twin brother.

The transferrin receptor is encoded by a diallelic locus which had been described as the T-cell antigenic system TCA. Using a human lymphoblastoid T-cell line (HSB) which reportedly carries a transferrin receptor and which we showed to be TCA-2 positive by serology, it appeared that only a TCA-2 but not a TCA-1 specific alloantiserum had the capacity to precipitate a protein with a molecular weight of 94,000, which comigrated exactly with the Mr 94,000 protein precipitated by the rabbit anti-HSB and rabbit anti-SB antisera, as well as the transferrin receptor which was precipitated by a transferrin-antitransferrin complex. The positive sera and the latter complex were shown to cross-react in a binding assay. Conversely, a monospecific TCA-1 alloantiserum was shown to react with the Mr 94,000 protein of TCA-1-positive leukocyte suspensions. The allelomorphism of the transferrin receptor may be relevant for the eventual regulatory mechanism controlling cell proliferation, which would be essential at least for those cells that are supposed to play an immunological role like the TCA-positive cells which are described as T-cells probably involved in the process of immunosuppression. In addition, we found increasing amounts of autoantibodies with TCA-1 specificity in serum from a healthy individual (referred to as "donor" in this paper), whose brother at the same time suffered a chronic myeloid leukemia, probably associated with a retrovirus, and whose blood in contrast was shown to contain cytotoxic anti-TCB, from a diallelic locus expressed on theophylline-insensitive T-cells, and anti-B-cell activity.

The effect of noninherited maternal antigens in allogeneic transplantation.

Confrontation of the unborn child immune system with the noninherited maternal antigens (NIMAs) has a lifelong modulating impact on the immune response of the child against the NIMAs. In this review we summarize the clinical evidence for the existence of the NIMA effect, discuss the possible cellular and molecular basis of the phenomenon, and outline the necessity of further clinical research.

Hypothyroidism during immunotherapy with interleukin-2 is associated with antithyroid antibodies and response to treatment.

PURPOSE: We investigated whether the association of interleukin-2 (IL-2) with hypothyroidism is related to the presence of thyroid autoantibodies, dose of IL-2, and clinical effectiveness of treatment, and reviewed the literature. PATIENTS AND METHODS: Sixteen cancer patients were treated with high-dose recombinant, continuous infusion IL-2 (18 x 10(6) IU/m2/d) and lymphokine-activated killer (LAK) cells. One patient previously treated for a toxic goiter with radioactive iodine was analyzed separately. Thyroid function and levels of thyroid antibodies were determined regularly. RESULTS: Seven of 15 patients (47%) became hypothyroid with high serum thyrotropin (TSH) levels within 60 to 120 days after the start of treatment; five responded favorably to treatment (one complete remission [CR], four partial remissions [PRs]), compared with none of the other eight patients. Two hypothyroid patients developed antimicrosomal antibodies (AMAs), one showed a further increase of antithyroglobulin antibodies (TgAbs), and six developed TgAbs. Only one of eight euthyroid patients developed slightly elevated TgAb levels. Development of hypothyroidism correlated significantly with a favorable response to treatment (r = .76, P = .001). The patient, treated with radioactive iodine, also became hypothyroid with high levels of TSH and development of AMAs and TgAbs. No difference was found between the hypothyroid and euthyroid patients in mean cumulative dose of IL-2 administered within the first 60 days or total treatment period, or with the relative dose-intensity. No other autoantibodies were found and patients had normal corticotropin (ACTH) stimulation tests. CONCLUSION: The likelihood of developing (transient) hypothyroidism is higher in patients who respond to IL-2 treatment. The development of antithyroid antibodies suggests that IL-2 treatment triggers autoreactive B-cell clones or that cellular and/or cytokine-mediated thyroid destruction leads to activation of autoreactive B-cell clones.

Results of allogeneic bone marrow transplants for leukemia using donors other than HLA-identical siblings.

PURPOSE: To compare outcomes of bone marrow transplants for leukemia from HLA-identical siblings, haploidentical HLA-mismatched relatives, and HLA-matched and mismatched unrelated donors. PATIENTS: A total of 2,055 recipients of allogeneic bone marrow transplants for chronic myelogenous leukemia (CML), acute myelogenous leukemia (AML), and acute lymphoblastic leukemia (ALL) were entered onto the study. Transplants were performed between 1985 and 1991 and reported to the International Bone Marrow Transplant Registry (IBMTR). Donors were HLA-identical siblings (n = 1,224); haploidentical relatives mismatched for one (n = 238) or two (n = 102) HLA-A, -B, or -DR antigens; or unrelated persons who were HLA-matched (n = 383) or mismatched for one HLA-A, -B, or -DR antigen (n = 108). HLA typing was performed using serologic techniques. RESULTS: Transplant-related mortality was significantly higher after alternative donor transplants than after HLA-identical sibling transplants. Among patients with early leukemia (CML in chronic phase or acute leukemia in first remission), 3-year transplant-related mortality (+/-SE) was 21% +/- 2% after HLA-identical sibling transplants and greater than 50% after all types of alternative donor transplants studied. Among patients with early leukemia, relative risks of treatment failure (inverse of leukemia-free survival), using HLA-identical sibling transplants as the reference group, were 2.43 (P < .0001) with 1-HLA-antigen-mismatched related donors, 3.79 (P < .0001) with 2-HLA-antigen-mismatched related donors, 2.11 (P < .0001) with HLA-matched unrelated donors, and 3.33 (P < .0001) with 1-HLA-antigen-mismatched unrelated donors. For patients with more advanced leukemia, differences in treatment failure were less striking: 1-HLA-antigen-mismatched relatives, 1.22 (P = not significant [NS]); 2-HLA-antigen-mismatched relatives, 1.81 (P < .0001); HLA-matched unrelated donors, 1.39 (P = .002); and 1-HLA-antigen-mismatched unrelated donors, 1.63 (P = .002). CONCLUSION: Although transplants from alternative donors are effective in some patients with leukemia, treatment failure is higher than after HLA-identical sibling transplants. Outcome depends on leukemia state, donor-recipient relationship, and degree of HLA matching. In early leukemia, alternative donor transplants have a more than twofold increased risk of treatment failure compared with HLA-identical sibling transplants. This difference is less in advanced leukemia.

Auto- and alloimmune reactivity to human islet allografts transplanted into type 1 diabetic patients.

Allogeneic islet transplantation can restore an insulin-independent state in C-peptide-negative type 1 diabetic patients. We recently reported three cases of surviving islet allografts that were implanted in type 1 diabetic patients under maintenance immune suppression for a previous kidney graft. The present study compares islet graft-specific cellular auto- and alloreactivity in peripheral blood from those three recipients and from four patients with failing islet allografts measured over a period of 6 months after portal islet implantation. The three cases that remained C-peptide-positive for >1 year exhibited no signs of alloreactivity, and their autoreactivity to islet autoantigens was only marginally increased. In contrast, rapid failure (<3 weeks) in three other cases was accompanied by increases in precursor frequencies of graft-specific alloreactive T-cells; in one of them, the alloreactivity was preceded by a sharply increased autoreactivity to several islet autoantigens. One recipient had a delayed loss of islet graft function (33 weeks); he did not exhibit signs of graft-specific alloimmunity, but developed a delayed increase in autoreactivity. The parallel between metabolic outcome of human beta-cell allografts and cellular auto- and alloreactivity in peripheral blood suggests a causal relationship. The present study therefore demonstrates that T-cell reactivities in peripheral blood can be used to monitor immune mechanisms, which influence survival of beta-cell allografts in diabetic patients.

How to improve the search for an unrelated haematopoietic stem cell donor. Faster is better than more!

Many patients do not reach haematopoietic stem cell transplantation. Shortage of unrelated donors (UDs) is still seen as the main cause. However, with a worldwide UD pool containing more than 8 million donors, it is possible that other impediments are becoming more important. We analysed 549 UD searches for Dutch patients, performed between 1987 and 2000, in order to find the reasons for failure or success to reach transplantation. Between 1996 and 2000, 59% of the patients of Northwest European origin received a graft from an UD with a median time span of 4.4 months from the start of the search. In all, 11% of the patients lacked a compatible donor, while 30% became medically unfit for transplantation. This is in contrast to the patients of non-Northwest European origin for whom UD shortage is still the most important impediment; only 32% were transplanted while 50% lacked a compatible donor. We conclude that the shortage of donors is no longer the biggest constraint in unrelated stem cell transplantation for patients of Northwest European origin. It may be more effective to optimize the chance on transplantation by making the search process more efficient.