Catheter length preference in wheelchair-using men who perform routine clean intermittent catheterization.

STUDY DESIGN: Prospective, unblinded, multicenter, randomized, controlled, cross-over study assessing user preference and ease of use characteristics of two gel intermittent catheters in 81 self-catheterizing wheelchair-using men. OBJECTIVES: To evaluate the male user's preference between a 30-cm and a 40-cm intermittent catheter (Apogee Intermittent Catheter, Hollister Incorporated, Libertyville, IL, USA) regarding the ease of insertion and removal, ability to control the catheter during insertion, bladder emptying confidence and ease of draining urine into a receptacle or connecting to a urine bag. SETTING: Multiple institutions in the United States. METHODS: Subjects were randomized to order of catheter use, using both 10 test catheters (30-cm) and 10 control catheters (40 cm). All catheters were 12 or 14 French and identical in design and composition, except length. Safety was assessed during the entire study period regarding adverse events (AE) and adverse device events (ADE). Subjects evaluated their ease of use characteristics after each catheter use and final catheter preference. RESULTS: Subjects preferred the Apogee 40-cm intermittent catheter (91.4%) over the 30-cm length (8.6%). The preference was due to subject confidence of complete bladder emptying (70%), more satisfactory length (74%) and easier to drain into a receptacle (58%) with a portable urinal being the most utilized (37%), followed by toilet (35%). The only AE/ADE reported was minor urethral bleeding in one subject and minor pain in another subject, both with the 30-cm catheter. None were reported with the 40-cm catheter. CONCLUSIONS: The Apogee 40-cm catheter was the preferred intermittent catheter due to subject confidence in bladder emptying, ease of catheter manipulation and the ease of draining urine into a receptacle.

Dose-dependent restoration of dystrophin expression in cardiac muscle of dystrophic mice by systemically delivered morpholino.

We have earlier shown that antisense morpholino oligomers are able to restore dystrophin expression by systemic delivery in body-wide skeletal muscles of dystrophic mdx mice. However, the levels of dystrophin expression vary considerably and, more importantly, no dystrophin expression has been achieved in cardiac muscle. In this study, we investigate the efficiency of morpholino-induced exon skipping in cardiomyoblasts and myocytes in vitro, and in cardiac muscle in vivo by dose escalation. We showed that morpholino induces targeted exon skipping equally effectively in both skeletal muscle myoblasts and cardiomyoblasts. Effective exon skipping was achieved in cardiomyocytes in culture. In the mdx mice, morpholino rescues dystrophin expression dose dependently in both skeletal and cardiac muscles. Therapeutic levels of dystrophin were achieved in cardiac muscle albeit at higher doses than in skeletal muscles. Up to 50 and 30% normal levels of dystrophin were induced by single systemic delivery of 3 g kg(-1) of morpholino in skeletal and cardiac muscles, respectively. High doses of morpholino treatment reduced the serum levels of creatine kinase without clear toxicity. These findings suggest that effective rescue of dystrophin in cardiac muscles can be achieved by morpholino for the treatment of Duchenne muscular dystrophy.

Microwave irradiation enhances gene and oligonucleotide delivery and induces effective exon skipping in myoblasts.

Microwave (MW) energy consists of electric and magnetic fields and is able to penetrate deep into biological materials. We investigated the effect of MW (2450 MHz) irradiation on gene delivery in cultured mouse myoblasts and observed enhanced transgene expression. This effect is, however, highly variable and critically dependent on the power levels, duration and cycle conditions of MW exposure. MW irradiation greatly enhances delivery of 2'O methyl-phosphorothioate antisense oligonucleotide (AON) targeting mouse dystrophin exon 23 and induces specific exon skipping in cultured myoblasts. Effective delivery of AON by MW irradiation is able to correct the dystrophin reading frame disrupted by a nonsense point mutation in the H2K mdx myoblasts, resulting in the restoration of dystrophin expression. MW-mediated nucleic acid delivery does not directly link to the increase in system temperature. The high variability in gene and oligonucleotide delivery is most likely the result of considerable irregularity in the distribution of the energy and magnetic field produced by MW with the current device. Therefore, achieving effective delivery of the therapeutic molecules would require new designs of MW devices capable of providing controllable and evenly distributed energy for homogenous exposure of the target cells.

The use of RNAi and transgenics to develop viral disease resistant livestock.

The possibility of genetically engineering poultry to make them resistant to avian influenza is attracting attention and has now become a real possibility with improved methods for genetic modification and the emergence of RNAi as an antiviral strategy. In order to test this possibility, we have generated transgenic mice that express RNAi molecules targeting a conserved region of the influenza A NP gene and are testing these mice for resistance to influenza infection. Transgenes were initially developed that express short hairpin RNAs (shRNAs) targeting multiple influenza A viral genes. The shRNAs were tested for inhibition of H1N1 PR8 virus in vitro. Two potent shRNAs that target the NP and PA genes were chosen for lentiviral mediated generation of transgenic mice. Transgenic founders for the NP shRNA construct and also a negative control shRNAtargeting EGFP were generated. The constitutive expression of the shRNA molecules in a range of tissue types including lung, was confirmed and so far stable transmission of the RNAi transgenes from the F0 to F3 generation has been observed. Resistance to influenza infection in these transgenic mice is now being confirmed.

Health equity monitoring for healthcare quality assurance.

Population-wide health equity monitoring remains isolated from mainstream healthcare quality assurance. As a result, healthcare organizations remain ill-informed about the health equity impacts of their decisions - despite becoming increasingly well-informed about quality of care for the average patient. We present a new and improved analytical approach to integrating health equity into mainstream healthcare quality assurance, illustrate how this approach has been applied in the English National Health Service, and discuss how it could be applied in other countries. We illustrate the approach using a key quality indicator that is widely used to assess how well healthcare is co-ordinated between primary, community and acute settings: emergency inpatient hospital admissions for ambulatory care sensitive chronic conditions ("potentially avoidable emergency admissions", for short). Whole-population data for 2015 on potentially avoidable emergency admissions in England were linked with neighborhood deprivation indices. Inequality within the populations served by 209 clinical commissioning groups (CCGs: care purchasing organizations with mean population 272,000) was compared against two benchmarks - national inequality and inequality within ten similar populations - using neighborhood-level models to simulate the gap in indirectly standardized admissions between most and least deprived neighborhoods. The modelled inequality gap for England was 927 potentially avoidable emergency admissions per 100,000 people, implying 263,894 excess hospitalizations associated with inequality. Against this national benchmark, 17% of CCGs had significantly worse-than-benchmark equity, and 23% significantly better. The corresponding figures were 11% and 12% respectively against the similar populations benchmark. Deprivation-related inequality in potentially avoidable emergency admissions varies substantially between English CCGs serving similar populations, beyond expected statistical variation. Administrative data on inequality in healthcare quality within similar populations served by different healthcare organizations can provide useful information for healthcare quality assurance.

Manipulation of small RNAs to modify the chicken transcriptome and enhance productivity traits.

In recent years there has been a revolution in our understanding of genes and how they come to control the physical outcomes of development. Central to this has been the understanding of the cellular processes of RNA interference (RNAi), for which the Nobel Prize for Physiology or Medicine was awarded in 2006. Coupled with this has been the recognition that microRNAs are key mediators of this process within cells. RNAi whether mediated exogenously by synthetic oligonucleotides or vector-delivered double stranded RNA or endogenously by microRNAs can have a profound and specific effect on gene expression. Elucidating and understanding these processes in the chicken will provide critical information to enable more precise control over breeding strategies for improvement of traits in production poultry, either by direct or indirect means. It will also provide alternative strategies for the control and prevention of important avian diseases.

Characterization of human sebaceous cells in vitro.

Human sebaceous cells, isolated from adult human skin, were cultured on either bovine type I collagen or mitomycin-C-treated 3T3 fibroblasts. Sebaceous cells, termed "sebocytes", were determined to be epithelial in nature by positive staining with monoclonal antikeratin antibodies BG2 and BG12. However, sebocyte colonies were also negative for keratins found in differentiated cells of keratinocyte colonies, as defined by monoclonal antikeratin antibodies CC2 and CC6. Sebocytes did not produce cornified envelopes in vitro and could only be induced to produce small quantities (less than 5%) of envelopes with a calcium ionophore. Sebocyte growth characteristics in a variety of serum, dexamethasone, and hydrocortisone combinations were significantly different from those of human facial keratinocytes. Sebocytes also displayed a growth curve and plating efficiency that were different from those of keratinocytes. Large lipid droplets within growing sebocytes could be visualized with oil red o staining. Additionally, squalene and wax/cholesterol esters were made by sebocytes in vitro in greater amounts than by facial keratinocytes, as determined by thin-layer chromatography of organic extracts of 3H2O-labeled sebocytes. Sebocytes synthesized greater quantities of lipid, on a per-cell and protein basis, than did keratinocytes.

Retinoid effects on sebocyte proliferation.

The human sebocyte model offers several advantages over the current animal models. Foremost among these is the correlation of in vitro activity with clinical results, which was not true for arotinoids in the animal models. It is also possible to study several parameters (total cell number, [3H]thymidine uptake, protein and lipid composition/synthesis, hormone response, receptor regulation, etc.) in the same system. The proliferation of isolated sebocytes is inhibited by retinoids, such as isotretinoin and tretinoin, which are known to be clinically active in human acne. Sebocytes are not responsive to the arotinoid temarotene, which is active in the aforementioned animal models and against dimethylbenz[a]anthracene (DMBA)-induced rat mammary carcinoma but inactive clinically in acne. Additionally, this model is not responsive to etretinate, a compound known to be active in psoriasis but inactive in acne. The in vitro model is, therefore, more predicative of clinical efficacy than the animal models alone.

A conformationally defined 6-s-trans-retinoic acid isomer: synthesis, chemopreventive activity, and toxicity.

A conformationally defined retinoic acid analog (1) which contains a dimethylene bridge to maintain the 6-s-trans orientation for two terminal double bonds in the polyene chain was synthesized. A Reformatsky reaction was utilized to extend the polyene chain of the starting enone, which provided exclusively the 9Z-configuration for the intermediate aldehyde. A Horners-Emmons condensation with this aldehyde then produced retinoic acid analogs with both 9Z- and 9Z,13Z-configurations. An I2-catalyzed isomerization of the intermediate 9Z-aldehyde yielded the all-E-aldehyde, which was olefinated as above to yield the (all-E)- and (13Z)-retinoic acid analogs of 1. Each configurational isomer of 1 was evaluated for its ability to inhibit the binding of retinoic acid to CRABP (chick skin) and to inhibit the chemical induction of ornithine decarboxylase in mouse skin. In each assay (all-E)-1 was the most active isomer, and this activity was comparable to or better than that for (all-E)-retinoic acid. (all-E)-1 and (13Z)-1 were both shown to be equally effective as (13Z)-retinoic acid in suppressing the proliferation of human sebaceous cells in vitro. (all-E)-1 was further evaluated for its ability to prevent the induction of mouse skin papillomas and to induce signs of vitamin A toxicity in mice. The cancer chemopreventive activity of (all-E)-1 was comparable to that of (all-E)-retinoic acid, and the toxicity was comparable to or slightly better than that of the natural vitamin.

IgA class antibodies and flow cytometric cross-matching in renal transplantation.

BACKGROUND: The established method of pretransplant cross-matching does not detect IgA antibodies, and IgA antibodies have thus been ignored when assessing patients for transplantation. The aim of this study was to detect IgA allo- and autoreactive antibodies using flow cytometry and to correlate the results with transplant outcome. METHODS: Pretransplant sera from 231 sequential renal recipients were tested for serum IgA levels and antibodies directed against the Fab portion of the human IgG molecule. Fifty-nine recipients with sufficient stored donor lymphocytes were also tested by flow cytometry for donor-specific alloantibodies of the IgA isotype. RESULTS: Graft survival was improved in recipients with higher IgA levels. High IgA anti-Fab levels led to a significantly higher 1-year graft survival (P<0.05). Graft survival was further enhanced where both serum IgA and IgA anti-Fab were raised (P<0.01). Although the mean IgA level tended to be higher for recipients with a positive IgA flow cytometric cross-match (FCXM), the IgA FCXM was not associated with increased IgA anti-Fab, suggesting that the IgA FCXM is detecting a different subset of IgA reactivity. Additionally, for primary grafts, a positive IgA FCXM was not associated with enhanced graft survival. CONCLUSIONS: Within the repertoire of IgA activity, there are two recognizable groups, the IgA anti-Fab specificity, which is significantly associated with enhanced graft survival, and that detected by the IgA FCXM, which surprisingly is more likely to be positive in less sensitized first grafts and is not associated with enhanced graft survival.

A large, single center investigation of the immunogenetic factors affecting liver transplantation.

BACKGROUND: Reports on the relevance of immunogenetic factors in liver transplantation are often conflicting or inconclusive. We have, therefore, investigated a range of factors that may underlie liver graft survival. METHODS: The influences of HLA, flow cytometric, and enhanced cytotoxic crossmatching and immunoglobulin (Ig)A levels on graft survival, and acute and chronic rejection were investigated for a single center involving 446 patients over 13 years. RESULTS: The effect of HLA mismatching on graft survival was significant (P<10(-2)) and was reversed in recipients with autoimmune diseases (P<0.5x10(-2)), whereas the effect of HLA mismatches on the level of acute rejection was detrimental in all recipients. There was a significant effect of a positive cytotoxic crossmatch on 3-month (P<10(-5)) and 1-year (P<10(-4)) graft survival, and an additional effect of the flow cytometric crossmatch was seen for chronic rejection (P<10(-2)) and acute rejection (P<10(-2)). Recipients with HLA-A1,B8,DRB1*0301 had higher levels of acute rejection (P<0.5x10(-2)), and recipients who received an ABO compatible-nonidentical transplant have a significantly higher risk (P<10(-2)) of developing chronic rejection. Finally, the beneficial effect of high serum IgA and, specifically, IgA anti Fab, seen in renal transplants was not evident in liver transplants, and in fact the opposite may be true, at least for acute rejection (P<0.5x10(-2)). CONCLUSIONS: By separating the recipients with autoimmune disease from other patients and by including acute and chronic rejection as outcome parameters, we have used the power of a large single-centre study to delineate the significance of some of the important immunogenetic factors involved in liver transplantation.

Unmasking and redistribution of lysosomal sulfated glycoconjugates in phagocytic polymorphonuclear leukocytes.

Rabbit heterophil and human neutrophil primary granules contain sulfated glycosaminoglycans (GAGs) and acid phosphatase, which can be readily stained in immature but not mature lysosomes. To determine whether this loss of staining represents masking of reactive components or removal of these components, we examined rabbit heterophils to see if high-iron diamine (HID)-reactive sulfate and acid phosphatase staining reappears in phagocytic vacuoles. Rabbit heterophils, obtained by peritoneal lavage, were incubated in vitro with latex beads or Pseudomonas aeruginosa for 15-60 min. Pre-embedment HID staining was enhanced in thin sections of unosmicated specimens with thiocarbohydrazide and silver proteinate (TCH-SP). Phagocytosis of latex beads or bacteria was progressively more prominent with time. Primary granules that were degranulated or in the process of degranulating into phagocytic vacuoles demonstrated intense sulfate staining with large (13 +/- 7 nm) HID-TCH-SP stain deposits. Smaller (6 +/- 1 nm) HID-TCH-SP stain deposits were present in tertiary granules, which were less frequently observed degranulating into phagosomes. Acid phosphatase staining was most intense during early phagolysosome formation. HID-TCH-SP staining was also observed in extracellular degranulated lysosomal matrices and on the surface of many peritoneal heterophils. These results indicate that loss of sulfate staining in mature heterophil granules is the result of masking by intragranular substances rather than of removal, and that these components may be unmasked during phagocytosis and/or redistributed to the cell surface after exocytosis.

Aseptic meningitis in infants younger than 2 years of age: acute illness and neurologic complications.

OBJECTIVE: We report the clinical features and cerebrospinal fluid (CSF) laboratory values for 277 children younger than 24 months of age with aseptic meningitis who were prospectively evaluated at three Baltimore hospitals between July 1986 and December 1990. A major objective was to define the incidence, etiology, and outcome of neurologic complications occurring during the acute illness. METHODS: Cases were identified by surveillance in the ambulatory care departments of each of the three hospitals, pertinent historical and clinical data were obtained by interview of the parents and by review of the medical records, initial CSF laboratory values were recorded, and appropriate specimens were submitted to determine the viral etiology. A subset of 216 children who participated in a long-term natural history study were followed periodically with neurologic examinations and formal neurodevelopmental testing. RESULTS: Most cases occurred in very young infants; 63.5% of patients were 8 weeks of age or younger, and 84.1% were younger than 16 weeks of age. In this very young cohort, the dominant symptoms were fever and irritability; only 8.7% had evidence of meningeal irritation at the initial examination. The acute illness was complicated by either complex seizures, physical evidence of increased intracranial pressure, or coma in 25 (9.0%) cases. Within the age group under study, these complications were each significantly more likely to occur in patients older than 12 weeks of age than in younger infants. The risk of neurologic complications was similar among infants infected with group B coxsackieviruses and echoviruses, the two major enterovirus classes observed to cause disease. Acute central nervous system (CNS) complications could not be correlated with extremely abnormal CSF laboratory indices. Importantly, there was no risk of long-term neurologic sequelae attributable to acute CNS complications. CONCLUSIONS: While approximately 9% of infants and children younger than 2 years of age with aseptic meningitis experience acute CNS complications in the form of complex seizures, increased intracranial pressure, or coma, the prognosis for long-term cognitive development appears to be as favorable as the prognosis for children with aseptic meningitis who do not experience these complications.

Amino acid sequences recognized by T cells: studies on a merozoite surface antigen from the FCQ-27/PNG isolate of Plasmodium falciparum.

Twenty-six overlapping peptides, spanning the entire FCQ-27/PNG sequence of the Plasmodium falciparum antigen known as merozoite surface antigen 2 were screened for their ability to induce the proliferation of peripheral blood lymphocytes (PBL) obtained from 12 donors living in Honiara, Solomon Islands where P. falciparum is endemic. A recombinant (r) form of MSA2, known as Ag 1609 was also screened in these assays and tetanus toxoid (TT) antigen was included as a control. The location of the predicted T cell determinants within MSA2 was examined using the algorithm, AMPHI and by scanning MSA2 for amino acid sequences showing the Rothbard motif. There were 13 predicted amphipathic helical sites and five examples of Rothbard sequences in the antigen. The location of these with regard to the peptides tested is shown. Nine of the 12 individuals responded to TT with high stimulation indices (greater than 4) being obtained in the majority of donors. Only three individuals responded to r-MSA2 with the stimulation indices (SI) in the range of 2.4-4.1. Peptides from both the constant and variable regions of MSA2 were recognized in the proliferative assays. However, the majority of the positive proliferative responses were to peptides which spanned the central variable region which included the two copies of the 32-amino-acid repeat occurring in the antigen. High SI comparable to those obtained to TT were seen in some individuals with some peptides. There was considerable variation between donors in number and nature of the peptides recognised and two donors did not respond to any of the antigens tested. The significance of these findings to vaccine development is discussed.

Evidence for the involvement of HLA-DR antigens in restricted cytotoxicity by fetal calf serum-specific human T cells.

Fetal calf serum (FCS) generated at least two distinct populations of human cytotoxic cells in vitro. One population expressed natural killer (NK) cell-like activity and lysed K562 and HSB-2 targets more effectively than autologous or allogeneic lymphoblastoid cell lines (LCLs). The other population contained FCS-specific cytotoxic T cells which preferentially lysed the autologous LCLs and showed minimal lysis of K562. E-rosette separation and cold target competition experiments clearly established that NK cells were not involved in the self-reactive lysis. Moreover, the lytic activity of the E-rosetted T cells was reduced by up to 95% when autologous target cells were grown in human AB serum rather than FCS, showing that FCS-associated determinants on targets were essential in the cytolytic phase. Autologous LCLs grown in FCS were also considerably stronger competitors than human serum-grown LCLs. The consistent self-preferred lysis suggested that HLA antigen-related restriction was involved, but the patterns of lysis did not implicate HLA-A or B antigens, and monoclonal antibody (W6/32) to an A, B, and C monomorphic determinant failed to block FCS-specific lysis. In contrast, monoclonal antibody (DA.2) to a monomorphic determinant of DR effectively blocked FCS-specific lysis. Cytotoxicity tests with a small panel of DR-typed donors indicated that strong cross-reactions were invariably associated with sharing of DR antigens, particularly DR2, and to a lesser but significant extent DR7. Although DR antigen sharing did not always result in lysis of allogeneic targets, the overall evidence strongly suggests that FCS-specific T-cell cytotoxicity in humans is restricted by products encoded by or associated with the DR genes.

Idiopathic haemochromatosis in the Australian population: HLA linkage and recessivity.

Studies of 78 unrelated patients and 19 families with idiopathic haemochromatosis are reported. The unrelated patients showed a highly significant association between the disease and HLA-A3. There was a less strong association with HLA-B7 and HLA-DRw2 attributed to the linkage disequilibrium between HLA-A3, B7, and DRw2. Lod scores and haplotype analysis of the families indicated a recessive mode of inheritance for an idiopathic haemochromatosis susceptibility factor in close linkage with the HLA region. These results, for Australian caucasoid patients, are not in total agreement with those reported in studies of other populations.

HLA studies of Highland and Coastal New Guineans.

The HLA profile of three New Guinean populations, two Highland (Asaro, Watut), and one Coastal is presented. The Highland populations are characterized by a low average number of alleles segregating at the HLA loci and also by a low mean value of heterozygosity at these loci. The genetic affinities of the two Highland groups with other Melanesian populations in the Pacific are remote. The Coastal group, on the other hand, shows strong similarities in its antigenic diversity and haplotypic combinations with other Melanesian populations. Nonetheless, the two Highland groups show significant divergence from each other in terms of allelic and haplotypic frequencies. Two different waves of migration settled in the Highlands of New Guinea between 10,000 and 15,000 years ago, and it is possible that the Watut, an Angan speaking group, represents the remnants of the first migration into the interior, whereas the Asaro, members of the Eastern Central family of the Trans-New Guinea phylum, arrived at a later date.

Family and twin studies in systemic lupus erythematosus.

We have estimated how much of the total genetic predisposition to SLE may be attributable to genes outside the HLA region by comparing figures for concordance of SLE in monozygotic twins with those for concordance in HLA identical siblings in Australia. None of six dizygotic co-twins of white Australian SLE probands was concordant for SLE. One of four (25%) monozygotic co-twins of white Australian SLE probands was concordant for SLE which when added to previously published figures for Caucasoid populations gives an overall concordance rate for SLE in monozygotic twins of 25%. None of 18 HLA identical, same sex siblings of SLE probands, had definite SLE by the study criteria (i.e. less than 6%). The comparison of these figures shows that most of the genetic predisposition to SLE is attributable to genes outside the HLA region.

Mother-to-child transmission of the human immunodeficiency virus in Texas.

BACKGROUND: The Pediatric Spectrum of HIV Diseases (PSD) project has been collecting data on HIV-exposed children in Texas since 1989. These data have now been analyzed to describe mother-to-child transmission in Texas and to provide much needed information on the magnitude of the pediatric HIV epidemic in the state. METHODS: We examined trends in the numbers of perinatally exposed children and perinatally acquired cases of HIV in the Texas PSD cohort. We calculated transmission rates and relative risks for 656 children born from January, 1995, to July, 1998, that received all or part of the ACTG 076 regimen. RESULTS: Only a small proportion (38%) of pairs of an HIV-infected mother and her HIV-exposed child received the full AIDS Clinical Trial Group 076 (ACTG 076) regimen; only 73% of the mothers received at least some prenatal care. In recent years, however, the numbers of perinatally exposed children and perinatally acquired cases of HIV have decreased in Texas. Univariate analyses showed that a reduction in the vertical transmission of HIV was associated with receipt of a full ACTG 076 regimen, receipt of a partial ACTG 076 regimen and residence in Dallas County. CONCLUSIONS: Findings identify a gap in meeting the health care needs of pregnant HIV-infected women and suggest missed opportunities to prevent mother-to-child transmission of HIV. At the same time this study confirms progress in prevention efforts to reduce mother-to-child transmission of HIV in Texas.

Pilot study of low-dose azathioprine in presensitized patients awaiting heart or lung transplantation.

In an effort to reduce the level of presensitization in patients on our heart and lung transplant waiting list, ten patients with random panel reactivity above 10% on monthly screening for durations of 2 to 59 months were given low-dose azathioprine (25 to 75 mg/day) for 1 to 22 months. All patients had positive T-cell panel reactivity (10% to 70%) against specific (n = 6), multi-specific (n = 1), or undefined (n = 3) HLA loci, and four additional patients had positive B-cell panel reactivity (5% to 40%). No effect of azathioprine on panel reactivity was seen in four of ten patients (40%), whereas a significant and sustained reduction in panel reactivity occurred in six patients (60%), all within 2 months of commencing azathioprine. All nonresponders had antibodies with class I (A locus) specificity, whereas all six responders had multi-specific or undefined antibody specificities. A formal trial of low-dose azathioprine in presensitized recipients is warranted.