Detection of Microchimerism After Allogeneic Blood Transfusion Using Nested Polymerase Chain Reaction Amplification With Sequence-Specific Primers (PCR-SSP): A Cautionary Tale

Maternal micro-chimeric cells in the multiple sclerosis brain

Maternal microchimeric cells (MMC) pass across the placenta from a mother to her baby during pregnancy. MMC have been identified in healthy adults, but have been reported to be more frequent and at a higher concentration in individuals with autoimmune diseases. MMC in brain tissue from individuals with autoimmune neurological disease has never previously been explored. The present study aims to identify and quantify MMC in adult human brain from control and multiple sclerosis (MS) affected individuals using fluorescent in situ hybridization (FISH) with a probe for the X and Y chromosomes. Post mortem brain tissue from 6 male MS cases and 6 male control cases were examined. Female cells presumed to be MMC were identified in 5/6 MS cases and 6/6 control cases. Cell specific labeling identified female cells of neuronal and immune phenotype in both control and active MS lesion tissue. This study shows that female cells presumed to be MMC are a common phenomenon in adult human brain where they appear to have embedded into brain tissue with the ability to express tissue specific markers.

Importance of extended blood group genotyping in multiply transfused patients

Blood group antigen systems are not limited to the ABO blood groups. There is increasing interest in the detection of extended blood group systems on the red cell surface. The conventional method used to determine extended blood group antigens or red cell phenotype is by serological testing, which is based on the detection of visible haemagglutination or the presence of haemolysis. However, this technique has many limitations due to recent exposure to donor red cell, certain drugs or medications or other diseases that may alter the red cell membrane. We aimed to determine the red cell blood group genotype by SNP real time PCR and to compare the results with the conventional serological methods in multiply transfused patients. Sixty-three patients participated in this study whose peripheral blood was collected and blood group phenotype was determined by serological tube method while the genotype was performed using TaqMan^® Single Nucleotide Polymorphism (SNP) RT-PCR assays for RHEe, RHCc, Kidd and Duffy blood group systems. Discrepancies were found between the phenotype and genotype results for all blood groups tested. Accurate red blood cell antigen profiling is important for patients requiring multiple transfusions. The SNP RT-PCR platform is a reliable alternative to the conventional method.

Naturally acquired microchimerism: implications for transplantation outcome and novel methodologies for detection

Microchimerism represents a condition where one individual harbors genetically distinct cell populations, and the chimeric population constitutes <1% of the total number of cells. The most common natural source of microchimerism is pregnancy. The reciprocal cell exchange between a mother and her child often leads to the stable engraftment of hematopoietic and non-hematopoietic stem cells in both parties. Interaction between cells from the mother and those from the child may result in maternal immune cells becoming sensitized to inherited paternal alloantigens of the child, which are not expressed by the mother herself. Vice versa, immune cells of the child may become sensitized toward the non-inherited maternal alloantigens of the mother. The extent of microchimerism, its anatomical location, and the sensitivity of the techniques used for detecting its presence collectively determine whether microchimerism can be detected in an individual. In this review, we focus on the clinical consequences of microchimerism in solid organ and hematopoietic stem cell transplantation, and propose concepts derived from data of epidemiologic studies. Next, we elaborate on the latest molecular methodology, including digital PCR, for determining in a reliable and sensitive way the extent of microchimerism. For the first time, tools have become available to isolate viable chimeric cells from a host background, so that the challenges of establishing the biologic mechanisms and function of these cells may finally be tackled.

Beneficial effects of pretransplantation microchimerism on rejection-free survival in HLA-haploidentical family donor renal transplantation

BACKGROUND

Fetal-maternal microchimerism (MC) can develop during pregnancy and may persist for decades. Pretransplantation fetal-maternal MC may be present between mother and child and between siblings; however, its effect on renal transplantation is not known. We investigated the effects of pretransplantation MC on allograft outcomes in human leukocyte antigen (HLA)-haploidentical family donor transplantation.

METHODS

A total of 106 cases transplanted from 1996 to 2004 were retrospectively studied, with median follow-up of 96 months. The study and control groups included 63 and 43 cases of HLA-haploidentical and HLA-identical donor transplantations, respectively. MC against mismatched donor HLA-DRB1 allele was detected in the recipient's peripheral blood using nested polymerase chain reaction-single-strand conformation polymorphism method. The allograft outcomes of HLA-haploidentical MC (+) and (-) subgroups were compared with those of HLA-identical group.

RESULTS

Pretransplantation MC in the HLA-haploidentical recipients was detected in 22.2% (14 of 63). Compared with HLA-identical group, MC (-) subgroup showed significantly inferior allograft outcomes: higher acute rejection rate (11.6% vs. 42.9%; P=0.001), higher 5-year serum creatinine level (1.1 vs. 1.4 mg/dL; P=0.009), and lower 10-year rejection-free survival rate (83.7% vs. 54.5%; log-rank P=0.001). In contrast, MC (+) subgroup showed no significant differences from HLA-identical group in acute rejection rate (14.3%), 5-year serum creatinine level (1.1 mg/dL), and 10-year rejection-free survival rate (85.7%). Multivariate analysis revealed that pretransplantation MC is associated with a significantly lower risk of acute rejection (odds ratio=0.10; P=0.021).

CONCLUSION

Pretransplantation MC present in the recipient may have beneficial effects on rejection-free allograft survival in renal transplantation.

Detection of HLA-DRB1 microchimerism using nested polymerase chain reaction and single-strand conformation polymorphism analysis

For the detection of microchimerism, molecular methods detecting donor-specific HLA-DRB1 alleles in the recipient are most commonly used. Nested polymerase chain reaction sequence specific primer (nested PCR-SSP) methods widely used to increase the sensitivity of detection have been reported to give frequent false-positive reactions. We have developed a new method combining nested PCR with single-strand conformation polymorphism analysis (nested PCR-SSCP) and tested the 1 to 0.00001% level of microchimerism for 27 different HLA-DRB1 alleles. For most (26/27) of the HLA-DRB1 alleles tested, this method could detect 0.01 to 0.001% of microchimerism and its sensitivity was equal to or better than that of nested PCR-SSP tested in parallel. Its specificity was verified by visualizing particular DRB1-specific SSCP bands under test. Nested PCR-SSP indicated frequent false-positive reactions, mainly caused by nonspecific amplification of DRB3/B4/B5 alleles present in the major (recipient) DNAs. We have compared a real-time quantitative PCR for non-human leukocyte antigen (HLA) target (insertion/deletion marker) using a commercial kit (AlleleSEQR Chimerism assay), and its microchimerism detection sensitivity (around 0.1%) was 1 step (10 times) lower than that of nested PCR-SSP or -SSCP methods for HLA-DRB1 alleles. We validated that the newly designed nested PCR-SSCP affords good sensitivity and specificity and may be useful for studying microchimerism in clinical settings.

HLA-targeted flow cytometric sorting of blood cells allows separation of pure and viable microchimeric cell populations

Microchimerism is defined by the presence of low levels of nonhost cells in a person. We developed a reliable method for separating viable microchimeric cells from the host environment. For flow cytometric cell sorting, HLA antigens were targeted with human monoclonal HLA antibodies (mAbs). Optimal separation of microchimeric cells (present at a proportion as low as 0.01% in artificial mixtures) was obtained with 2 different HLA mAbs, one targeting the chimeric cells and the other the background cells. To verify purity of separated cell populations, flow-sorted fractions of 1000 cells were processed for DNA analysis by HLA-allele-specific and Y-chromosome-directed real-time quantitative PCR assays. After sorting, PCR signals of chimeric DNA markers in the positive fractions were significantly enhanced compared with those in the presort samples, and they were similar to those in 100% chimeric control samples. Next, we demonstrate applicability of HLA-targeted FACS sorting after pregnancy by separating chimeric maternal cells from child umbilical cord mononuclear cells. Targeting allelic differences with anti-HLA mAbs with FACS sorting allows maximal enrichment of viable microchimeric cells from a background cell population. The current methodology enables reliable microchimeric cell detection and separation in clinical specimens.

Plasma gelsolin and circulating actin correlate with hemodialysis mortality

Plasma gelsolin (pGSN) binds actin and bioactive mediators to localize inflammation. Low pGSN correlates with adverse outcomes in acute injury, whereas administration of recombinant pGSN reduces mortality in experimental sepsis. We found that mean pGSN levels of 150 patients randomly selected from 10,044 starting chronic hemodialysis were 140 +/- 42 mg/L, 30 to 50% lower than levels reported for healthy individuals. In a larger sample, we performed a case-control analysis to evaluate the relationship of pGSN and circulating actin with mortality; pGSN levels were significantly lower in 114 patients who died within 1 yr of dialysis initiation than in 109 survivors (117 +/- 38 mg/L versus 147 +/- 42 mg/L, P < 0.001). pGSN levels had a graded, inverse relationship with 1-yr mortality, such that patients with pGSN < 130 mg/L experienced a > 3-fold risk for mortality compared with those with pGSN > or = 150 mg/L. The 69% of patients with detectable circulating actin had lower pGSN levels than those without (127 +/- 45 mg/L versus 141 +/- 36 mg/L, P = 0.026). Compared with patients who had elevated pGSN and no detectable actin, those with low pGSN levels and detectable actin had markedly increased mortality (odds ratio 9.8, 95% confidence interval 2.9 to 33.5). Worsening renal function correlated with pGSN decline in 53 subjects with CKD not on dialysis. In summary, low pGSN and detectable circulating actin identify chronic hemodialysis patients at highest risk for 1-yr mortality.

Microchimerism and renal transplantation: doubt still persists

OBJECTIVE

We sought to study microchimerism in a group of kidney transplant recipients.

MATERIALS AND METHODS

In this study, the peripheral blood microchimerism (PBM) after renal transplantation was retrospectively evaluated in 32 male-to-female recipients of living unrelated or cadaveric donor renal transplants. Using a nested polymerase chain reaction (PCR) amplification specific for SRY region of the Y chromosome, microchimerism was detected with a sensitivity of 1:1,000,000. Recipients were compared according to the presence of PBM, acute and chronic rejection episodes, type of allotransplant, recipient and donor age at transplantation, previous male labor or blood transfusion, allograft function (serum creatinine level), and body mass index.

RESULTS

Among 32 recipients, 7 (21.9%) were positive for PBM upon multiple testing at various posttransplant times. All microchimeric recipients had received kidneys from living unrelated donors. No significant difference was observed with regard to other parameters. In addition the acute rejection rate in the microchimeric group was 3 (42%) versus 4 (16%) in the nonmicrochimeric recipients (not significant).

CONCLUSION

Our results suggested better establishment of microchimerism after living donor kidney transplantation. However, doubt persists concerning the true effect of microchimerism after renal transplantation. It seems that microchimerism alone has no major protective role upon renal allograft survival.

Microchimerism evaluation in recipients of living-related or unrelated deceased allograft renal transplants

The presence of microchimerism in the peripheral blood of solid organ graft recipients has been associated with long-term solid organ acceptance, immunologic tolerance, and less aggressive immunosuppressive therapy. Molecular biology assays are among the most sensitive methods to detect microchimerism, primarily to evaluate Y chromosome sequences in females as indirect evidence of circulating male nucleated donor cells. We screened for the presence of the SRY sequence region in peripheral blood of 13 female recipients of male kidney grafts: 5 living-related and 8 deceased grafts. Only patients who received grafts from related living donors exhibited microchimerism. Five of 13 patients studied exhibited better graft outcomes, including the 4 who were positive for the SRY sequences.

Identification of maternal hematopoietic cells in a 2nd-trimester fetus

OBJECTIVE

To study the subset of maternal cells in fetal tissue in a 2nd-trimester fetus with malformations.

METHODS

By cell sorting and PCR amplification, we studied the presence of maternal CD3+ (T cells), CD19+ (B cells), CD34+ (hematopoietic progenitor cells), and CD45+ (leukocytes) in different tissues in a 2nd trimester fetus.

RESULTS

Maternal cells could be detected in fetal liver, lung, heart, thymus, spleen, adrenal gland, kidney, and placenta, but not in pancreas or gonadal tissue. In thymus, liver, and spleen, cell separation showed CD3+, CD19+, CD34+, and CD45+ positive cells of maternal origin.

CONCLUSIONS

The present study indicates that maternal cells are widely distributed in a 2nd-trimester fetus. In addition, we found subpopulations of maternal cells belonging to lymphoid and myeloid lineages and hematopoietic progenitors with engraftment capacity in liver, spleen, and thymus. The study warrants further investigations on presence and possible biological function of maternal cells in normal and malformed fetuses.

Can post-mortem blood be used for DNA profiling after peri-mortem blood transfusion?

The question of whether blood transfusions can affect DNA profiling is still a contentious issue throughout the forensic community. It is hypothesised that donor leucocytes present in the administered blood will be detected upon examination of recipient blood. In order to resolve this issue, a selection of theoretical experiments were carried out to determine how much donor DNA must be present for its detection in blood components. Five casework examples of material collected from individuals after massive transfusion, including a case of whole organ transplantation, were also investigated. The results indicated that filtration processes used during blood production do not allow the passage of enough donor leucocytes for detection using current forensic profiling techniques. No evidence of secondary profile alleles were found in any case, indicating that peri-mortem blood transfusion does not affect DNA profiling.

Short tandem repeat (STRs) and sex specific Amelogenin analysis of blood samples from neurosurgical female transfused patients

Blood transfusion and its effects on DNA profiles of an individual is an important issue in the forensic context. In the present study, the effects of unfiltered whole male blood transfusion in seven female subjects were investigated by PCR-based assays on serial post-transfusion blood samples. PCR analysis of specific short tandem repeat (STR) primer pair to CSF1PO, TPOX, TH01, F13A01, FESFPS, vWA and sex specific Amelogenin loci for banding pattern of alleles generated from the pre- and post-transfusion of seven female recipients and their corresponding donors were studied. Pre- and post-transfusion DNA profiles of all the seven female recipients were found to be consistent with no evidence of the male and female donor genetic material. It is concluded that currently used PCR-based STRs and sex specific Amelogenin loci DNA profiling techniques in forensic science are reliable and informative for paternity and identity purposes in situations of transfusion of 1 or 2 U of unfiltered whole male and female blood (> 72 h old) to female recipient up to 24 h post-transfusion.

Separating human DNA mixtures using denaturing high-performance liquid chromatography

DNA mixtures represent challenging samples that are rarely amenable to direct DNA sequence analysis and many of the strategies available to separate mixtures are both labor and time intensive. Denaturing high-performance liquid chromatography is an accurate and rapid approach for the detection and scoring of mutations. It can also be used to separate DNA mixtures. The technique relies on the chromatographic separation of crosshybridization products to isolate the individual components of a mixture. By eliminating secondary amplification and excessive manipulation prior to sequencing, denaturing high-performance liquid chromatography can streamline the analysis of conditions ranging from somatic mosaicism, microchimerism and mitochondrial heteroplasmy to evidentiary material containing mixtures of DNA encountered in forensic investigations.

Microchimerism after liver transplantation: absence of rejection without abrogation of anti-donor cytotoxic T-lymphocyte-mediated alloreactivity

Microchimerism (MC) is defined by the persistence of <1% circulating donor cells resulting from cell migration from the graft; MC may play a role in the induction of unresponsiveness to allogeneic tissues, or may be merely the consequence of the graft's acceptance following immunosuppression. To analyze early MC (7 patients) and late MC (12 patients) following a liver transplantation, we designed a sensitive and semiquantitative nested polymerase chain reaction (PCR) protocol based on the detection of incompatible human leukocyte antigen (HLA)-DRB1 donor alleles. MC was measured in multiple PCR samples and expressed as percent positive PCRs / time point. The detection level was 1 donor cell / 10(5) patient cells. All patients had detectable early MC, ranging from 5 to 100% positive PCRs in the 1st 3 months after transplantation. The kinetic analysis demonstrated that MC decreased during the 1st year in 6 of 7 patients. All of the 4 patients with the lowest MC had rejection episodes, vs. none among the 3 patients with MC >50%. However, cytotoxic T-lymphocyte reactivity (CTL) against HLA class I donor antigens could be demonstrated 1 year posttransplant in 2 patients with a high level of early MC. MC is a dynamic process, which is easily detectable <3 months after liver transplantation. In conclusion, a correlation between the level of early MC and the absence of rejection episodes was observed. However, high levels of early MC did not abrogate the persistence of an alloreactive response measured in vitro 1 year after transplantation, which suggests that MC did not lead to clonal deletion of donor-specific CTL.

Microchimerism in immune competent patients related to the leukocyte content of transfused red blood cell concentrates

BACKGROUND

Microchimerism may play a part in transfusion complications. The aim of this study was to examine whether establishment of post-transfusion microchimerism was related to leukocyte content.

METHODS

Twenty non-pregnant female patients, without known malignant or immunological diseases, mean age 68 years, receiving 2-4 units of red blood cell concentrates during elective surgery, were included. One or two of the units were from male donors. Ten patients received buffy-coat depleted red blood cell concentrates, leukocyte count 108-109 per unit, and 10 patients received red blood cells leukoreduced by prestorage leukocyte filtration, with a leukocyte count of <106 per unit. EDTA samples were collected in vacuum tubes before and after 1 week and 6 months after transfusion. The tubes were frozen and stored at -400 degrees C. Genomic DNA was isolated and PCR performed using four primer sets amplifying markers on the Y-chromosome.

RESULTS

Microchimerism was detected in a total of eight out of the 20 patients. In three patients microchimerism was detected only before transfusion. These patients had given birth to one or two boys each, and had no history of previous transfusion. Two patients receiving buffy-coat depleted red blood cell concentrates and two patients receiving leukoreduced red blood cell concentrates had detectable microchimerism 1 week after transfusion. The age of the transfused red blood cell concentrates was 6, 24, 8 and 7 days, respectively. One patient receiving leukoreduced red blood cell concentrates had detectable microchimerism after 6 months. The age of this concentrate was 22 days.

DISCUSSION

This study demonstrates that microchimerism after transfusion does not seem to be dose dependent, and can be induced even by a >3 week old leukoreduced red blood cell concentrate with a very low leukocyte content.

Genotyping patients with recent blood transfusions

BACKGROUND

Many studies have used polymerase chain reaction amplification (PCR) to genotype for common polymorphisms in intensive-care units (ICUs) where blood transfusions are common. Evidence that donor leukocytes in transfused blood can be detected by PCR of the recipient blood suggests that this minor population of donor white cells (microchimerism) can interfere with genotyping of allelic polymorphisms in critically ill transfused patients. To investigate this possibility, we assayed DNA extracted from the blood and buccal cells of ICU patients for 2 common polymorphisms in the TNF-beta gene and the surfactant protein-B (SP-B) gene.

METHODS

Study subjects were ICU patients from the Massachusetts General Hospital (Boston, MA) enrolled into a study on the molecular epidemiology of acute respiratory distress syndrome between January 1999 and October 2000. Blood and buccal cells were collected and DNA was extracted from 145 patients. Genotyping was performed by enzyme digestion and pyrosequencing.

RESULTS

The Kappa statistics comparing the genotype results from blood and buccal cells were 0.98 (95% confidence interval [CI] = 0.94-1.01) for TNFB and 0.95 (CI = 0.87-1.02) for SP-B. When the analysis was restricted only to the 107 patients who were transfused, the Kappa statistic remained high at 0.97 (CI = 0.93-1.01) for TNFB and 0.93 (CI = 0.84-1.03) for SP-B.

CONCLUSION

We conclude that microchimerism from allogeneic blood transfusion is unlikely to have major effects on the genotype results of common polymorphisms in large molecular epidemiology studies conducted in the critical care setting if DNA is collected within a day after transfusions.

Multiplex amplification and fluorimetric detection of short tandem repeats for mixed chimerism after bone marrow transplant

We present the clinical application of a simple method for mixed chimerism analysis after allogeneic bone marrow (BM) or peripheral blood stem cell (PBSC) transplant. A commercial kit which enables multiplex amplification of 9 highly polymorphic short tandem repeats in a single reaction tube was used. Molecular size and relative quantities of each amplified fragment are subsequently measured using an automated fluorimeter. The sensitivity and linearity were tested using whole blood or genomic DNA from two subjects, mixed in various proportions from 0.25% to 99.75%. In 70 donor-recipient pairs the median number of informative alleles for the assessment of relapse was 5.9 (range 3-11). Results showed that the linearity between the measured and expected relative quantities of amplified DNA showed a regression coefficient of 0.99 in the interval 10-90%. The mean sensitivity was 1.5% (range 0.5-2.5), greater than previously reported. A total of 70 cases of allogeneic transplant (49 with family and 21 with unrelated donors) were monitored before transplant and after 1, 2, 4, 6 or 12 months thereafter and then at 6 months intervals (range 6-36). In 18 patients mixed chimerism was observed 1 month from transplant, with donor allele percentage ranging from 1 to 6%. Fragment dimension reproducibility (CV 0.34, range 0.52-0.66) was confirmed by an internal DNA control and by amelogenin fragment length repeatability on all patients. In conclusion, the proposed method is sufficiently simple, rapid, sensible, specific and cost effective for the evaluation of mixed chimerism after BM or PBSC transplant in a clinical setting.

HLA-DRB1 allele polymorphisms in genetic susceptibility to esophageal carcinoma

AIM: To probe into the genetic susceptibility of HLA-DRB1 alleles to esophageal carcinoma in Han Chinese in Hubei Province.

METHODS: HLA-DRB1 allele polymorphisms were typed by polymerase chain reaction with sequence-specific primers (PCR-SSP) in 42 unrelated patients with esophageal cancer and 136 unrelated normal control subjects and the associated HLA-DRB1 allele was measured by nucleotide sequence analysis with PCR.SAS software was used in statistics.

RESULTS: Allele frequency (AF) of HLA-DRB1*0901 was significantly higher in esophageal carcinoma patients than that in the normal controls (0.2500 vs 0.1397, P = 0.028, the odds ratio 2.053, etiologic fraction 0.1282). After analyzed the allele nucleotide sequence of HLA-DRB1*0901 which approachs to the corresponded exon 2 sequence of the allele in genebank. There was no association between patients and controls in the rested HLA-DRB1 alleles.

CONCLUSION: HLA-DRB1*0901 allele is more common in the patients with esophageal carcinoma than in the healthy controls, which is positively associated with the patients of Hubei Han Chinese. Individuals carrying HLA-DRB1*0901 may be susceptible to esophageal carcinoma.

Restriction fragment length polymorphism and polymerase chain reaction: HLA-DQA1 and polymarker analysis of blood samples from transfusion recipients

The effect of blood transfusion on DNA profiles of an individual is a significant issue in the forensic context. In the present study, the effects of blood transfusion in 5 recipients were studied by performing restriction fragment length polymorphism and polymerase chain reaction HLA-DQA1 and Polymarker (LDLR, GYPA, HBGG, D7S8, and GC) assays (Roche Molecular Systems, Branchburg, NJ) on serial posttransfusion blood samples. Pretransfusion and posttransfusion DNA profiles of all 5 recipients were consistent with no evidence of the donor genetic material. Currently used DNA profiling techniques in forensic science are reliable and informative for paternity and identity purposes in situations involving transfusion of 1 or 2 U of blood up to 24 hours posttransfusion.

Real-time sequence-specific primer polymerase chain reaction amplification of HLA class II alleles: a novel approach to analyze microchimerism

The careful assessment of microchimerism is essential to investigate the effects of donor bone marrow-derived cells in transplantation. We have developed a protocol to assess microchimerism based on the HLA mismatch between the recipient and the donor. Our approach combines real-time polymerase chain reaction (PCR) with sequence-specific primer PCR (SSP-PCR) to selectively amplify and measure the abundance of donor HLA alleles in DNA samples extracted from the recipient after transplant. To optimize and validate the reliability of this method at different levels of microchimerism, we tested serial dilutions of donor DNA into recipient DNA. We demonstrate that donor alleles can be readily detected and reliably measured at concentrations as low as 0.1%. This method is simple and rapid and could find practical application in the assessment of microchimerism in patients receiving organ or cellular transplants in conjunction with donor bone marrow cells infusion.

Survival of transfused donor white blood cells in HIV-infected recipients

The appearance and expansion of donor white blood cells in a recipient after transfusion has many potential biologic ramifications. Although patients with HIV infection are ostensibly at high risk for microchimerism, transfusion-associated graft-versus-host disease (TA-GVHD) is rare. The purpose of this study was to search for sustained microchimerism in such patients. Blood samples were collected from 93 HIV-infected women (a subset from the Viral Activation Transfusion Study, an NHLBI multicenter randomized trial comparing leukoreduced versus unmodified red blood cell [RBC] transfusions) before and after transfusions from male donors. Donor lymphocytes were detected in posttransfusion specimens using a quantitative Y-chromosome-specific polymerase chain reaction (PCR) assay, and donor-specific human leukocyte antigen (HLA) alleles were identified with allele-specific PCR primers and probes. Five of 47 subjects randomized to receive nonleukoreduced RBCs had detectable male lymphocytes 1 to 2 weeks after transfusion, but no subject had detectable male cells more than 4 weeks after a transfusion. In 4 subjects studied, donor-specific HLA haplotypes were detected in posttransfusion specimens, consistent with one or more donors' cells. None of 46 subjects randomized to receive leukoreduced RBCs had detectable male lymphocytes in the month after transfusion. Development of sustained microchimerism after transfusion in HIV-infected patients is rare; HIV-infected patients do not appear to be at risk for TA-GVHD.

Prospective study of microchimerism in renal allograft recipients: association between HLA-DR matching, microchimerism and acute rejection

The presence of donor-derived hematopoietic cells in blood and various tissues of the organ recipients, termed allogeneic microchimerism, has been considered to play an essential role in establishment of organ acceptance. In this study, we prospectively determined the presence of peripheral blood microchimerism (PBM) in 20 male-to-female renal allograft recipients up to 30 months post-transplantation. Recipients were categorized according to the pattern of microchimerism into microchimeric and nonmicrochimeric groups, and then state of human leukocyte antigens (HLA) Class II (DR/DQ) matching, episodes of acute rejection, age at transplantation, renal function, and history of blood transfusion were compared. DNA was extracted from donor, pre-transplant, and post-transplant (1 wk; 1, 3, 6, 12, 18, 24, and 30 months) peripheral blood samples. We analyzed PBM using nested polymerase chain reaction (PCR) amplification specific for the SRY region of the Y chromosome with a sensitivity up to 1:1 000 000. Microchimerism was detected in 13 (65%) of 20 recipients at various intervals. The highest frequency of microchimerism was at 1 wk (55%). Among microchimeric recipients, none were positive on all post-transplant analyses. Interestingly, nonmicrochimeric cases were negative throughout the study. The three recipients with an episode of acute rejection during the first week after transplantation were all in the nonmicrochimeric group with completely mismatched HLA-DR antigens. HLA-DR incompatibility was significantly lower (t-test, p<0.05) in microchimeric cases (1.0+/-0.58) than in nonmicrochimeric ones (1.9+/-0.38). But regarding HLA-DQ and other clinical parameters mentioned above, significant difference was not observed. We propose that there is an association between HLA-DR matching, microchimerism and acute graft rejection in our recipients. Our study demonstrates that, with routine immunosuppressive protocols, higher compatibility of HLA-DR antigens facilitates microchimerism induction. Then, development of new stronger immunosuppressive protocols (including conditioning) or augmentation of chimeric state (by donor-specific bone marrow infusion), especially in completely mismatched HLA-DR renal allograft recipients, may be useful for graft acceptance.

Differentiation of autologous ABO, RHD, RHCE, KEL, JK, and FY blood group genotypes by analysis of peripheral blood samples of patients who have recently received multiple transfusions

BACKGROUND

After multiple transfusions, the serologic typing of autologous blood group phenotypes is difficult, because of mixed RBC populations. The genotyping of ABO, Rh, Kell, Kidd, and Duffy systems could be used to determine autologous blood group antigen status.

STUDY DESIGN AND METHODS

Blood samples from patients and donors were analyzed before and after 26 multiple-transfusion events. An average of 6.9 non-WBC-reduced RBC units with an average age of 5.9 days were administered per transfusion event. The average period of blood sampling after transfusions was 5.3 days. All samples were serologically phenotyped for ABO, Rh, Kell, Kidd, and Duffy. Pretransfusion, posttransfusion, and buccal samples from patients were genotyped for the corresponding alleles by a uniform PCR sequence-specific primer protocol that allowed their simultaneous determination within 3 hours.

RESULTS

All posttransfusion samples exhibited mixed-cell populations of various blood group systems on serologic testing. Genotyping from peripheral blood produced results identical to the autologous blood group phenotypes, regardless of the amount of blood transfused or of the length of the sampling period after transfusion.

CONCLUSION

A fast and reliable PCR-sequence-specific primer DNA genotyping assay for simultaneous determination of autologous ABO, Rh, Kell, Kidd, and Duffy blood groups can be performed on peripheral blood samples, even though the patients have recently received multiple transfusions.

Microchimerism in bone marrow–derived CD34+ cells of patients after liver transplantation

Lymphoid and dendritic cells of donor origin can be detected in the recipient several years after a solid organ transplantation. This phenomenon is termed microchimerism and could play a role in the induction of tolerance. The fate of other hematopoietic cells transferred by liver transplantation, in particular of stem and progenitor cells, is unknown. For this reason, we studied peripheral blood and bone marrow samples of 12 patients who had received a liver transplant from an HLA-DR mismatched donor. Eight patients were long-term survivors between 2.8 and 10.1 years after allografting. CD34+ cells from bone marrow were highly enriched with the use of a 2-step method, and a nested polymerase chain reaction was applied to detect donor cells on the basis of allelic differences of the HLA-DRB1 gene. Rigorous controls with DRB1 specificities equal to the donor and host were included. In 5 of 8 long-term liver recipients, donor-specific CD34+ cells could be detected in bone marrow. Microchimerism in the CD34+ cell fraction did not correlate to the chimeric status in peripheral blood. In conclusion, our results demonstrate a frequent microchimerism among bone marrow–derived CD34+ cells after liver transplantation. The functional role of this phenomenon still needs to be defined.

Microchimerism in bone marrow–derived CD34+ cells of patients after liver transplantation

Lymphoid and dendritic cells of donor origin can be detected in the recipient several years after a solid organ transplantation. This phenomenon is termed microchimerism and could play a role in the induction of tolerance. The fate of other hematopoietic cells transferred by liver transplantation, in particular of stem and progenitor cells, is unknown. For this reason, we studied peripheral blood and bone marrow samples of 12 patients who had received a liver transplant from an HLA-DR mismatched donor. Eight patients were long-term survivors between 2.8 and 10.1 years after allografting. CD34+ cells from bone marrow were highly enriched with the use of a 2-step method, and a nested polymerase chain reaction was applied to detect donor cells on the basis of allelic differences of the HLA-DRB1 gene. Rigorous controls with DRB1 specificities equal to the donor and host were included. In 5 of 8 long-term liver recipients, donor-specific CD34+ cells could be detected in bone marrow. Microchimerism in the CD34+ cell fraction did not correlate to the chimeric status in peripheral blood. In conclusion, our results demonstrate a frequent microchimerism among bone marrow–derived CD34+ cells after liver transplantation. The functional role of this phenomenon still needs to be defined.

Kinetic analysis of microchimerism induced by intrathymic injection of allogeneic splenocytes in mice

Allograft survival facilitated by intrathymic (i.t.) injection of allogeneic cells have shown that modifications of T-cell development induce specific tolerance. One hypothesis is that the resulting microchimerism may play a role in preparing the host immune system for the allograft. To investigate whether the deliberate introduction of allogeneic splenocytes into the thymus of adult mice allows the establishment of a lasting donor/recipient microchimerism, a full allogeneic mouse system (H-2 and Mls) with additional sex mismatch was used. Male cells injected into female mice were detected using an optimized nested-polymerase chain reaction which specifically amplifies the SRY gene with a sensitivity of 1/10(4). After i.t. injection, donor cells were observed early both in the lymph nodes and spleen (75 and 25% of mice, respectively). They were still present on day 6, although preferentially in the thymus (100% of mice) than in the lymph nodes (50% of mice) or in the spleen (22% of mice). After intraperitoneal (i.p.) or subcutaneous (s.c.) injection, donor cells were early (2 h) but transiently detected in the thymus, since on day 6 they were detected in 0 and 17% of mice after i.p. and s.c. injection, respectively. Kinetics of donor-cell detection was similar both in the spleen and lymph nodes with a clear decrease in the percentage of mice with donor-cell detection between day 2 and day 6 (20 and 17% of positive mice for the spleen after i.p. and s.c. injections, respectively--20 and 33% of positive mice for the lymph nodes after i.p. and s.c. injections, respectively). Our results clearly show that i.t. injection of allogeneic splenocytes induces a microchimerism which is both more lasting and detected in a higher percentage of mice than by the i.p. and s.c. routes, both at the central (thymus) and peripheral (spleen) levels.

Nested Polymerase Chain Reaction With Sequence-Specific Primers Typing for HLA-A, -B, and -C Alleles: Detection of Microchimerism in DR-Matched Individuals

It is widely accepted that donor leukocytes survive within the recipient periphery after blood transfusion or solid organ transplantation. The significance of this microchimerism remains unclear, partially because of the insecurity of assays used to detect the donor-derived material. The techniques used to detect donor-derived DNA within recipient peripheral blood rely largely on major histocompatibility complex class II polymorphism. We and others have shown that the sensitivity of polymerase chain reaction with sequence-specific primers (PCR-SSP) typing for HLA class II alleles can be increased 100-fold by the addition of a primary amplification step (nested PCR-SSP). We have now extended this technique to encompass typing for HLA class I alleles, thereby adding flexibility to microchimerism testing by enabling testing of recipients HLA-DR matched with their donors. However, the high level of sensitivity achieved with the technique (1:100,000) leads to a concomitant decrease in the specificity that results in the amplification of unexpected products, a phenomenon we encountered in the development of our nested PCR-SSP typing system for HLA class II alleles. We describe here how it is possible to compensate for these anomalies by including multiple testing of a pretransfusion sample that acts as a specificity control, establishing a rigorous baseline for subsequent analysis.

Nested Polymerase Chain Reaction With Sequence-Specific Primers Typing for HLA-A, -B, and -C Alleles: Detection of Microchimerism in DR-Matched Individuals

It is widely accepted that donor leukocytes survive within the recipient periphery after blood transfusion or solid organ transplantation. The significance of this microchimerism remains unclear, partially because of the insecurity of assays used to detect the donor-derived material. The techniques used to detect donor-derived DNA within recipient peripheral blood rely largely on major histocompatibility complex class II polymorphism. We and others have shown that the sensitivity of polymerase chain reaction with sequence-specific primers (PCR-SSP) typing for HLA class II alleles can be increased 100-fold by the addition of a primary amplification step (nested PCR-SSP). We have now extended this technique to encompass typing for HLA class I alleles, thereby adding flexibility to microchimerism testing by enabling testing of recipients HLA-DR matched with their donors. However, the high level of sensitivity achieved with the technique (1:100,000) leads to a concomitant decrease in the specificity that results in the amplification of unexpected products, a phenomenon we encountered in the development of our nested PCR-SSP typing system for HLA class II alleles. We describe here how it is possible to compensate for these anomalies by including multiple testing of a pretransfusion sample that acts as a specificity control, establishing a rigorous baseline for subsequent analysis.