Material radiopurity control in the XENONnT experiment

The selection of low-radioactive construction materials is of the utmost importance for rare-event searches and thus critical to the XENONnT experiment. Results of an extensive radioassay program are reported, in which material samples have been screened with gamma-ray spectroscopy, mass spectrometry, and \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$^{222}$$\end{document}222Rn emanation measurements. Furthermore, the cleanliness procedures applied to remove or mitigate surface contamination of detector materials are described. Screening results, used as inputs for a XENONnT Monte Carlo simulation, predict a reduction of materials background (\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\sim $$\end{document}∼17%) with respect to its predecessor XENON1T. Through radon emanation measurements, the expected \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$^{222}$$\end{document}222Rn activity concentration in XENONnT is determined to be 4.2 (\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$^{+0.5}_{-0.7}$$\end{document}-0.7+0.5) \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\upmu $$\end{document}μBq/kg, a factor three lower with respect to XENON1T. This radon concentration will be further suppressed by means of the novel radon distillation system.

Variation in a range of mTOR-related genes associates with intracranial volume and intellectual disability

De novo mutations in specific mTOR pathway genes cause brain overgrowth in the context of intellectual disability (ID). By analyzing 101 mMTOR-related genes in a large ID patient cohort and two independent population cohorts, we show that these genes modulate brain growth in health and disease. We report the mTOR activator gene RHEB as an ID gene that is associated with megalencephaly when mutated. Functional testing of mutant RHEB in vertebrate animal models indicates pathway hyperactivation with a concomitant increase in cell and head size, aberrant neuronal migration, and induction of seizures, concordant with the human phenotype. This study reveals that tight control of brain volume is exerted through a large community of mTOR-related genes. Human brain volume can be altered, by either rare disruptive events causing hyperactivation of the pathway, or through the collective effects of common alleles.

A single-center experience of cytomegalovirus infections in Asian pediatric patients undergoing allogeneic hematopoietic stem cell transplant for leukemia in Singapore

INTRODUCTION

Cytomegalovirus (CMV) infection remains a significant cause of morbidity and mortality in pediatric patients undergoing allogeneic hematopoietic stem cell transplantation (HSCT) despite improved surveillance and the current preemptive approach. Few data on its prevalence in the Asian pediatric population exist.

METHODS

We retrospectively reviewed the prevalence of CMV infections in 33 patients with 37 transplants who received HSCT for leukemia from 1998 to 2008, and who were managed preemptively for infections.

RESULTS

In the 37 transplants, 16 patients (43%) had CMV DNAemia. Of the patients who were CMV seropositive before transplant and received stem cells from seropositive donors (R+/D+), 69% had DNAemia; of those who received stem cells from seronegative donors (R+/D-), 36% had CMV DNAemia. Of the patients who were CMV naïve before transplant and received stem cells from seropositive donors (R-/D+), 25% had CMV DNAemia. In CMV-seronegative donor-recipient transplants (R-/D-), 20% of patients had CMV DNAemia. The median time to the first episode of CMV DNAemia was 21 (range: 10-107) days after the transplants, and the median duration of CMV DNAemia was 22 (range: 2-315) days. CMV DNAemia recurred in 44% (7 of 16) of these patients. Only 1 patient developed CMV disease (retinitis). No deaths were related to CMV infections.

CONCLUSIONS

CMV infection manifesting as DNAemia is a common complication in pediatric patients undergoing allogeneic HSCT for leukemia. Pre-transplant serostatus predicts reactivation risks; invasive CMV disease is rare using the preemptive approach in our patient population.

Severe Kikuchi's disease responsive to immune modulation

Kikuchi's disease, although an uncommon entity, has been increasingly reported since it was first discovered in 1972. The most common manifestation of Kikuchi's disease, cervical lymphadenopathy, has no clinically distinguishable features. Therefore, a diagnosis of Kikuchi's disease has largely been based on clinical suspicion and histopathological confirmation. We present a 15-year-old Chinese girl with severe Kikuchi's disease, whose relapsing course was only responsive to highdose steroid and intravenous immunoglobulin therapy.

The ability of ultrasound to detect gynaecological neoplasms and their ultrasound morphological features

To determine first, the accuracy of a gynaecological ultrasound service in the detection of four clinically significant pathologies, namely, uterine body malignancy, ovarian malignancy, ovarian dermoid cysts and other benign ovarian pathologies and second, to review the ultrasound imaging appearances of ovarian masses with histopathological correlation. Retrospective data collection from consecutive weekly multidisciplinary team meetings over a 12-month period. All patients had undergone ultrasound examination before surgery. Data included patient demographics, menopausal status, indications for ultrasound, type of practitioner carrying out the scan, operative findings and final histopathological diagnosis. Ultrasound imaging appearances were correlated to histology. Of the 47 cases of uterine malignancy, 45 had endometrial carcinoma. All had either a thickened or poorly seen or not seen endometrium. Twenty-four per cent of these women were premenopausal. Forty-seven of the 48 cases of ovarian malignancy had abnormal ultrasound findings. In six of these, the findings were of a purely cystic lesion. There were 62 cases of benign ovarian pathology (excluding dermoid cyst), all of which had an abnormal ultrasound; 16 of these had possible ultrasound features of malignancy. All 30 cases of ovarian dermoid cyst had an abnormal ultrasound with a specific diagnosis being made in 27. This study shows that ultrasound is accurate in the detection of both endometrial and ovarian disease. The endometrium that is not seen or is poorly seen is an indication for endometrial biopsy in women with postmenopausal bleeding. There is considerable overlap in the ultrasound appearances of benign and malignant ovarian lesions. Ultrasound is a good method for the accurate and specific diagnosis of an ovarian dermoid cyst.

Bilateral pleural effusions following central venous cannulation

We describe a patient who developed bilateral pleural effusions as a delayed complication following central venous catheter insertion. Respiratory distress should not only raise the clinical suspicion of a pneumothorax but also of erosion and perforation of the central vein. The mechanism, diagnosis, management and prevention of this complication are discussed.

The Transplantation Society--new key opinion leaders of tomorrow 2006

One of the new initiatives taken by the immediate past president of The Transplantation Society, KJ Wood, is to introduce a new series of meetings named 'New Key Opinion Leaders of Tomorrow'. The Transplantation Society invites the leading young investigators in the field of transplantation to participate in this meeting together with the present leaders of the field. The key objective of this meeting is to identify the potential key opinion leaders of tomorrow. Each presentation during the meeting was jointly given by the senior and junior investigators. The meeting in Buenos Aires covered six main topics on clinical, translational and basic transplantation. These included: innate immunity and inflammation; transplant infectious diseases; tumour and transplantation; medical and ethical aspects of transplantation; dendritic cells (stimulating and manipulating the immune response to a transplant); and ABO incompatible donor recipient pairs. This report focuses on the emerging biological therapeutics and their ramifications on clinical transplantation.

Diffusion weighted magnetic resonance imaging for acute stroke: practical and popular

AIM

To evaluate the feasibility and impact of diffusion weighted magnetic resonance imaging (DW MRI) as the first line neuroimaging of stroke at a district general hospital.

METHODS

Prospective audit of all in-patients admitted with clinically suspected acute stroke and referred for imaging over a consecutive 17 week period. The data collected included scan type, time from cerebral event to imaging request, and time from formal radiological request to neuroimaging. Clinicians' (general physicians, neurologists, and radiologists) perceptions were assessed by a questionnaire.

RESULTS

148 patients had neuroimaging for clinically suspected stroke during this period. Eighty one per cent of patients (120 of 148) had DW MRI as first line. Ninety two per cent of these patients had DW MRI within 24 hours of the formal radiological request. Twenty eight patients did not undergo DW MRI because lack of MRI safety, clinical state, unavailability because of maintenance service or lack of trained staff. Clinicians found the introduction of the DW MRI based service a significant improvement on computed tomography, especially for equivocal cases.

CONCLUSION

DW based MRI service is both feasible and sustainable in the setting of a district general hospital and most clinicians feel that this is a significant improvement to stroke services.

Cerclage-wiring-assisted fixation of difficult hand fractures

Difficult hand fractures with multiple butterfly fragments, multiple cortical splits or intraarticular extension continue to pose a challenge for optimal stable fixation that allows early postoperative mobilisation. In this study, we describe the use of cerclage-wire-assisted fixation of 17 difficult hand fractures in 16 patients. The cerclage wires helped to maintain the reduction, so providing sufficient initial stability for placement of a plate and screws. Stable fixation of the fracture was then accomplished without losing the reduction. One to three cerclages of stainless-steel wires were used for the preliminary fixation. Stable fixation was then accomplished by a bridging or neutralising plate technique. Postoperatively, the fixation was sufficiently stable to allow immediate mobilisation. With an average follow up of 44.5 months, all 17 fractures united without loss of reduction. At final follow-up, the average total active range of motion was 247 degrees (range 220-260 degrees ).

MRI of the diabetic foot: differentiation of infection from neuropathic change

The aim of this review is to illustrate the magnetic resonance imaging features that can help differentiate osteomyelitis from neuropathic osteoarthropathy in the foot.

Central venous catheters: the role of radiology

The insertion and management of long-term venous catheters have long been the province of anaesthetists, intensive care physicians and surgeons. Radiologists are taking an increasing role in the insertion of central venous catheters (CVCs) because of their familiarity with the imaging equipment and their ability to manipulate catheters and guide-wires. The radiological management of the complications of CVCs has also expanded as a result. This article reviews the role of radiology in central venous access, covering the detection and management of their complications.

Radiological appearances in the pelvis following rectal cancer surgery

Radiology has a significant role in the evaluation of surgery for rectal cancer. With recent developments in surgical techniques, the number of neorectal reservoir configurations has increased. It is important to recognize the normal and abnormal appearances, both early and late, following pelvic surgery. The aim of this pictorial review is to demonstrate the imaging techniques that are used in both the investigation and the follow-up of patients who have undergone uncomplicated or complicated rectal resection.

Incidental heterotopic pregnancy demonstrated on magnetic resonance imaging

We report a case of an assisted pregnancy in an asymptomatic woman who was found to have an extrauterine mass on ultrasound and MRI. This complex mass had equivocal imaging features and was found to be a ruptured ovarian ectopic pregnancy at surgery. This case illustrates that vigilance is required regarding the possibility of coexisting ectopic and intrauterine pregnancy following assisted conception, even in entirely asymptomatic cases.

A randomised placebo controlled trial of delipidated, deglycolipidated Mycobacterium vaccae as immunotherapy for psoriatic arthritis

OBJECTIVES

To test the hypothesis that PVAC, delipidated, deglycolipidated heat killed Mycobacterium vaccae, is an effective and safe treatment for psoriatic arthritis (PsA). This treatment has shown promising results in psoriasis.

METHODS

36 patients with PsA in two centres were studied in this double blind, placebo controlled, randomised trial. Patients were randomised to receive two intradermal injections of 50 micro g PVAC or placebo and were followed up for 24 weeks. The primary end point was the Psoriatic Arthritis Response Criteria (PsARC), a composite measure based on changes in joint tenderness and swelling scores and physician and patient global assessments.

RESULTS

The PsARC response at either 12 or 24 weeks was achieved by 9/18 (50%) placebo and 9/18 (50%) PVAC patients (p = 1.0). No significant differences in the Psoriasis Activity and Severity Index (PASI), patient or physician global assessments, CRP, or Health Assessment Questionnaire score over time were found between the two groups. However, changes in the pain visual analogue scale over time did differ between the two groups (p = 0.006): at 24 weeks the mean score in the PVAC group had declined by 19.2 mm and in the placebo group had increased by 4.8 mm. PVAC was well tolerated with no increased incidence of adverse events compared with placebo.

CONCLUSIONS

PVAC was not shown to be as effective as immunotherapy for PsA. The striking response to placebo in this study reinforces the importance of adequately controlling therapeutic trials in PsA.

Thiopurine methyltransferase polymorphisms in a multiracial asian population and children with acute lymphoblastic leukemia

The purpose of this study was to determine the frequency of thiopurine methyltransferase (TPMT) polymorphisms in a multiracial Asian population and to assess its relevance in the management of childhood acute lymphoblastic leukemia (ALL). Six hundred unrelated cord blood samples from 200 Chinese, Malay, and Indian healthy newborns were collected at the National University Hospital, Singapore; an additional 100 children with ALL were analyzed for five of the commonly reported TPMT variant alleles using polymerase chain reaction/restriction fragment length polymorphism and allele-specific polymerase chain reaction-based assays. In the cord blood study, the TPMT*3C variant was detected in all three ethnic groups; Chinese, Malays, and Indians had allele frequencies of 3%, 2.3%, and 0.8%, respectively. The TPMT*3A variant was found only among the Indians at a low allele frequency of 0.5%. The TPMT*6 variant was found in one Malay sample. Among the children with ALL, two white and one Chinese were heterozygous for the TPMT*3A variant and showed intermediate sensitivity to 6-mercaptopurine during maintenance therapy. Three Chinese patients and one Malay patient were heterozygous for the TPMT*3C variant. Mercaptopurine sensitivity could be validated in only one out of four TPMT*3C heterozygous patients. The overall allele frequency of the TPMT variants in this multiracial population was 2.5%. The TPMT*3C was the most common variant allele; TPMT*3A and TPMT*6 were rare. These results support the feasibility of performing TPMT genotyping in all children diagnosed with acute leukemia to minimize toxicity from thiopurine chemotherapy.

In vitro activity of moxifloxacin against local bacterial isolates

INTRODUCTION

The emergence of resistance to common antimicrobials in bacteria has been increasingly reported in various countries. Empirical antimicrobial therapy of various infections would therefore need to be reviewed. The introduction of new fluoroquinolones has created an interest in the use of these as possible agents in the empirical treatment of respiratory tract infections.

MATERIALS AND METHODS

The minimum inhibitory concentration (MIC) of the new fluoroquinolone, moxifloxacin, against 400 clinical bacterial isolates was determined by the E-test method.

RESULTS

All Streptococcus pneumoniae isolates (penicillin sensitive or resistant) were susceptible to moxifloxacin. Similarly, both beta-lactamase and non beta-lactamase producing Haemophilus influenzae and Moraxella catarrhalis isolates were susceptible to moxifloxacin. As for Enterobacteriaceae, 88.6% of the isolates tested were susceptible to moxifloxacin with MIC < 8 mg/L, but resistance was noted for some of Proteus mirabilis, Klebsiella spp. and Escherichia coli. Enterococci and Acinetobacter baumannii were resistant to moxifloxacin, whilst the anaerobes tested were susceptible to moxifloxacin.

CONCLUSION

Moxifloxacin has good in vitro activity against common organisms associated with community and nosocomial infections, with the exception of enterococci, methicillin-resistant Staphylococcus aureus and ciprofloxacin-resistant gram-negative bacteria. There was good anti-anaerobic activity against Bacteroides fragilis and Clostridum spp. Results of this study are consistent with other similar published in vitro studies.

The effect of delipidated deglycolipidated (DDMV) and heat-killed Mycobacterium vaccae in asthma

Experimental and epidemiological evidence supports the hypothesis that exposure to mycobacteria has the potential to suppress the development of asthma and/or atopy and there are reports in the Chinese medical literature of repeated vaccination with inactivated BCG being effective in the management of asthma. Forty-three patients with stable moderately severe asthma who were skin prick test positive to house dust mite were randomized to receive two intradermal injections of either phosphate-buffered saline (placebo), heat-killed Mycobacterium vaccae (0.5 mg), or delipidated deglycolipidated Mycobacterium vaccae (DDMV) (0.05 mg). Markers of asthma severity were measured for 3 mo and blood eosinophil, IgE levels, and the T cell proliferative and cytokine responses were monitored. There were no significant differences between either treatment group and the placebo group for any of the outcome variables. There was also no difference between the treatment groups and placebo for eosinophil, IgE levels, or the T cell proliferative and cytokine response. The results indicate no effect of low dose intradermal DDMV or M. vaccae on asthma severity in patients with established asthma.

Improvement in psoriasis after intradermal administration of delipidated, deglycolipidated Mycobacterium vaccae (PVAC): results of an open-label trial

The aim of new treatments for psoriasis is to induce extended remissions with fewer side-effects. Previous studies suggest that Mycobacterium vaccae, a harmless organism prepared as a heat-killed suspension, may induce periods of remission in some psoriasis patients after intradermal administration. To assess a more potent derivative of M. vaccae, we conducted an open-label study in which 20 patients with moderate to severe psoriasis (Psoriasis Area and Severity Index of 12-35) received two intradermal inoculations of heat-killed, delipidated, deglycolipidated M. vaccae (DD-MVAC or 'PVAC') in lesion-free deltoid skin, separated by a period of 3 weeks. Twelve weeks after the injections, 13 out of 20 patients (65%) showed marked improvement in the PASI score (> 50% reduction), three were unchanged (< 25% reduction), three had worsened (> 5% increase), and one was withdrawn from the trial because of an exfoliative flare. At 24 weeks, 13 out of 19 patients continued to show > 50% improvement that, in some, lasted for 6 months or longer. Patients classified as good responders at 12 or 24 weeks were then offered additional PVAC injections after 24 weeks if the PASI reached 8 or higher. Intra-dermal administration of PVAC was safe, well tolerated, and induced clinically significant improvement in many psoriasis patients. A randomized, double-blind, controlled study is warranted.

Twin studies of immunogenicity--determining the genetic contribution to vaccine failure

CONTEXT

Estimating the magnitude of the genetic contribution to the overall variation of antibody levels among individuals should help clarify the role of genetic association in the biological mechanism of vaccine response and failure. This, in turn, should help guide the design of improved vaccines with enhanced efficacy.

OBJECTIVE

To explore the magnitude of genetic influence on antibody levels following measles, mumps and rubella vaccines.

DESIGN

Cross-sectional survey study.

SETTING

Olmsted County, Minnesota.

PARTICIPANTS

Healthy twin-pairs. Of the 100 twin-pairs enrolled, 45 were monozygotic.

INTERVENTIONS

Determinations of zygosity, vaccine status, and quantitative IgG to measles, mumps, and rubella.

MAIN OUTCOME MEASURE

Heritability (ratio of genetic variance to total variance).

RESULTS

The number of vaccine-doses, the age at initial immunization, and the time between immunization and sampling did not differ between monozygotic and dizygotic twin pairs. The genetic variance - the variance in antibody levels presumably due to genetic effects - was 0.49 for measles, 0.54 for mumps, and 0.13 for rubella. Heritability, the ratio of genetic variance to total variance, was 88.5% for measles, with the lower bound of a one-sided 95% confidence interval equal to 52.4%. The heritability was, for mumps, 38.8% with a lower bound of 1.60%. The heritability for rubella was 45.7% with a lower bound of 4.94%.

CONCLUSION

Our data support the concept that genetic influences play a substantial role in the variation of antibody levels following immunization against measles and, to a lesser extent, mumps and rubella.

The ability of heat-killed Mycobacterium vaccae to stimulate a cytotoxic T-cell response to an unrelated protein is associated with a 65 kilodalton heat-shock protein

Exogenous antigens are generally presented by Class II major histocompatibility (MHC) molecules. When administered with an adjuvant, however, they are capable of inducing a CD8+ T-cell response where antigen recognition is associated with Class I MHC. Accordingly, immunization with soluble ovalbumin (OVA) alone does not activate CD8+ cytotoxic T cells (CTL) but when given in complete Freund's adjuvant (CFA), or in formulations of a number of novel adjuvants, an OVA-specific CD8+ CTL response can be detected. We show in this report that immunization with soluble OVA mixed with heat-killed Mycobacterium vaccae, but not with other common pathogenic and saprophytic mycobacteria, can activate OVA-specific CD8+ CTL. An OVA-specific CTL response is detected when mice are immunized by either the intraperitoneal or intranasal route and their spleen cells are re-stimulated in vitro. Adjuvant activity of heat-killed M. vaccae is present in M. vaccae culture filtrate, in soluble protein components of whole M. vaccae and in the 65 kDa heat-shock protein (hsp) of M. vaccae. Mycobacterium vaccae has previously been shown to have no adverse side-effects in humans. The current results suggest that M. vaccae may be useful as an adjuvant for vaccines and other immunotherapies where CD8+ CTL responses to exogenous proteins are crucial.

Dysregulated expression of CD69 and IL-2 receptor alpha and beta chains on CD8+ T lymphocytes in flaky skin mice

T-cell activation is considered to be an important element in the pathogenesis of psoriasis, a human skin disease characterized by keratinocyte hyperproliferation, altered keratinocyte differentiation and inflammation of the dermis and epidermis. Mice homozygous for the flaky skin (fsn) mutation develop a skin disorder that has histopathological and biochemical features resembling some forms of psoriasis. It has been reported recently that peripheral lymph nodes (PLN) in fsn/fsn mice exhibit various abnormalities in T-cell development suggestive of dysregulated T- and B-cell activation. In the present study, the expression of the inducible T-cell activation antigens CD69 and IL-2 receptor alpha chain (CD25) on PLN cells from fsn/fsn mice and their phenotypically normal littermates is examined. Expression of CD69 was significantly increased on PLN cells in fsn/fsn mice (mean +/- SD, 49.9 +/- 14.7% of cells) compared with control mice (14.6 +/- 4.2%). Analysis of CD4+ and CD8+ T cell subsets revealed that expression of CD69 in fsn/fsn PLN was significantly biased toward CD8+ cells. Although expression of CD25 was preferentially associated with CD4+ rather than CD8+ cells in both fsn/fsn and control PLN, with most CD4+ CD25+ cells being CD25hi, the proportion of CD4+ cells expressing CD25 was higher in fsn/fsn than control PLN. In contrast, CD25 was expressed by 2-3% of CD8+ PLN cells in both fsn/fsn and control mice and CD25hi cells accounted for < 1% of CD8+ cells in fsn/fsn PLN. The paucity of CD25 on CD8+ cells in fsn/fsn PLN did not appear to be due to a defect in the ability of these cells to upregulate CD25, because T cell receptor stimulation in vitro induced high expression of CD25 on both CD4+ and CD8+ cells. A striking and consistent finding was that most CD8+ cells in fsn/fsn PLN expressed high levels of IL-2R beta chain (CD122). In contrast, CD122 was expressed at low levels on CD8+ cells in control mice. Analysis of PLN cells from newborn fsn/fsn mice revealed that the high expression of CD122 on CD8+ cells was established by 2 weeks of age, prior to the appearance of clinical skin disease. These data indicate that large numbers of T cells in fsn/fsn mice are activated and reinforce the view that fsn is an important regulator of lymphocyte development and function. The relationship between T-cell activation and flaky skin disease in these mice remains to be established.

Gene expression in rat dermal papilla cells: analysis of 2529 ESTs

Dermal papilla (DEPA) cells are resident at the base of hair follicles and are fundamental to hair growth and development. Cultured DEPA cells, in contrast to normal fibroblast cells, are capable of inducing de novo hair follicle growth in vivo. By differential screening of a DEPA cDNA library, we have demonstrated that dermal papilla cells are different from fibroblasts at the molecular level. We further studied these cells by random sequencing of 5130 clones from the DEPA cDNA library. Fifty percent had a BLASTX E value < or =1 x 10(-25). Twenty-one percent had similarity to proteins involved in cell structure/motility with 4 of the top 10 most abundant clones encoding extracellular matrix proteins. Clones encoding growth factor molecules were also abundant. The remaining 50.7% of clones had low similarity scores, demonstrating many novel molecules. For example, we identified a new CTGF family member, the rat homologue of Elm1.

A 1-year follow-up study of dynamic magnetic resonance imaging in early rheumatoid arthritis reveals synovitis to be increased in shared epitope-positive patients and predictive of erosions at 1 year

OBJECTIVES

Dynamic magnetic resonance imaging (MRI) allows visualization of the synovial membrane and measurement of synovitis within the joint. A cohort of patients with early rheumatoid arthritis (RA) were studied using MRI of the dominant wrist and clinical assessments. Associations between synovitis and the shared epitope genotype (SE) were looked for and synovitis as a predictor of joint erosion was examined.

METHODS

Gadolinium-enhanced MRI scans of the dominant wrist were performed in 42 early RA patients at baseline (median disease duration = 4 months) and after 1 yr. Images were obtained at 42-s intervals over the first 6 min after gadolinium-diethylenetriamine pentaacetic acid injection using six cuts in the coronal plane, 2 mm apart. The site of maximal synovial enhancement was selected as the region of interest (ROI). The rate of enhancement (E-rate) was calculated and compared with synovitis scores from static MRI scans, clinical disease activity scores and HLA-DRB1*04/01 genotyping [sequence-specific primer polymerase chain reaction (SSP-PCR) and DNA sequencing].

RESULTS

Reproducibility of the E-rate measurement was assessed by re-evaluating 10 randomly selected scans in a blinded fashion. Intra-observer reliability was high with an intraclass correlation coefficient of 0.91, 95% confidence interval (CI) 0.65-0.97. The E-rate correlated strongly at baseline with the maximum level of synovial enhancement (E-max) (r = 0.88, P < 0.0001) and the static MRI synovitis score (r = 0.52, P = 0.0004). There was also a weaker but significant correlation between E-rate and the pain score (r = 0.29, P = 0.04). The E-rate fell from baseline to 1 yr (P = 0.02) concordant with clinical improvement after treatment with standard therapies. E-rate scores were higher in SE+ than SE - patients (F(1,25) = 5.19, P = 0.03) and were predictive of MRI erosions at 1 yr [chi-square = 5.0 (1 d.f.), P = 0.03]. The baseline C-reactive protein (CRP) was also predictive of MRI erosions at 1 yr to a similar degree [chi-square = 4.7 (1 d.f. ), P = 0.03] but the mean static synovitis score at baseline was the strongest predictor [chi-square = 9.2 (1 d.f.), P = 0.003].

CONCLUSIONS

These results show that dynamic MRI can be used to score synovitis objectively in early RA patients. Synovitis was greater in SE+ patients, suggesting an early genetic influence on joint inflammation, and was predictive for the development of erosions at 1 yr.

The peripheral lymphoid compartment is disrupted in flaky skin mice

Flaky skin (fsn) is an autosomal recessive mutation on mouse chromosome 17 that causes severe anaemia, forestomach papillomatosis and a papulosquamous skin disease that resembles psoriasis in humans. In the present paper, it is reported that fsn causes peripheral lymphadenopathy, CD4/CD8 imbalance and hyperresponsiveness to T cell growth factors. Peripheral lymph nodes (PLN) of adult mutant (fsn/fsn) mice were found to contain almost 10-fold more leucocytes than PLN from phenotypically normal littermates (+/fsn or +/+, hereafter referred to as +/?). Analysis of PLN cells using mAbs and flow cytometry revealed that this predominantly lymphoid hyperplasia was characterized by approximately equivalent increases in the numbers of CD3+ T cells and CD19+ B cells. However, expansion within the T cell compartment was non-random, because fsn/fsn PLN had a considerably reduced ratio of CD4+ to CD8+ T cells (1.08 +/- 0.37) compared to +/? PLN (2.47 +/- 0.44, P < 0.0001). In vitro assays of cellular proliferation in response to T and B cell growth factors showed that fsn/fsn PLN cells were hyperresponsive to IL-2, IL-4 and IL-7 when compared with PLN cells from +/? mice. Studies using mesenteric lymph node and peripheral blood cells showed that hyperresponsive cells are widely distributed in fsn/fsn mice. Experiments in newborn mice showed that the lymphoid disturbances caused by fsn are established at least as early as 2 weeks of age, a time that precedes the onset of the earliest clinical skin lesions. These data implicate a role for the fsn gene product in regulating the size and content of the peripheral lymphoid compartment.

Improvement in psoriasis after intradermal administration of heat-killed Mycobacterium vaccae

BACKGROUND

New treatments for psoriasis are being developed, but many are associated with limited efficacy, side-effects, or rapid recurrence after discontinuation. Thus, the aim of new agents is to induce longer term remissions with fewer side-effects. Preliminary studies have shown that Mycobacterium vaccae, a nonpathogenic organism prepared as a heat-killed suspension, may induce periods of remission in some psoriasis patients when administered intradermally.

METHODS

To further assess the efficacy and tolerability of M. vaccae in patients with moderate to severe psoriasis (psoriasis area and severity index (PASI) of 12-35), we conducted an open label study whereby 24 patients received two intradermal inoculations of M. vaccae in lesion-free deltoid skin, separated by a period of 3 weeks.

RESULTS

Twelve weeks after starting treatment, 14 of 24 patients (58%) showed marked improvement in the PASI score (greater than 50% reduction), two had moderate improvement (25-50% reduction), six were unchanged (< 25% reduction), and two had worsened (> 5% increase). By 24 weeks, 11 of 22 patients continued to show greater than 50% improvement. Five patients had complete clearance of skin lesions that lasted for at least 6 months.

CONCLUSIONS

Intradermal administration of heat-killed M. vaccae suspension was well tolerated and induced clinically significant improvement in a majority of psoriasis patients in this cohort. Placebo-controlled testing to further define the efficacy of this treatment is warranted.

Magnetic resonance imaging of the wrist in early rheumatoid arthritis reveals progression of erosions despite clinical improvement

OBJECTIVES

To investigate the progression of joint damage in early rheumatoid arthritis (RA) using magnetic resonance imaging (MRI) of the wrist and determine whether this technique can be used to predict prognosis.

METHODS

An inception cohort of 42 early patients has been followed up prospectively for one year. Gadolinium enhanced MRI scans of the dominant wrist were obtained at baseline and one year and scored for synovitis, tendonitis, bone marrow oedema, and erosions. Plain radiographs were performed concurrently and scored for erosions. Patients were assessed clinically for disease activity and HLA-DRB1 genotyping was performed.

RESULTS

At one year, MRI erosions were found in 74% of patients (31 of 42) compared with 45% at baseline. Twelve patients (28.6%) had radiographic erosions at one year. The total MRI score and MRI erosion score increased significantly from baseline to one year despite falls in clinical measures of inflammation including erythrocyte sedimentation rate (ESR), C reactive protein (CRP), and swollen joint count (p < 0.01 for all). Baseline findings that predicted carpal MRI erosions at one year included a total MRI score of 6 or greater (sensitivity: 93.3%, specificity 81.8%, positive predictive value 93.3%, p = 0.000007), MRI bone oedema (OR = 6.47, p < 0.001), MRI synovitis (OR = 2.14, p = 0.003), and pain score (p = 0.01). Radiological erosions at one year were predicted by a total MRI score at baseline of greater than 13 (OR = 12.4, p = 0.002), the presence of MRI erosions (OR = 11.6, p = 0.005), and the ESR (p = 0.02). If MRI erosions were absent at baseline and the total MRI score was low, radiological erosions were highly unlikely to develop by one year (negative predictive value 0.91 and 0.92 respectively). No association was found between the shared epitope and erosions on MRI (p = 0.4) or radiography (p = 1.0) at one year.

CONCLUSIONS

MRI scans of the dominant wrist are useful in predicting MRI and radiological erosions in early RA and may indicate the patients that should be managed aggressively. Discordance has been demonstrated between clinical improvement and progression of MRI erosion scores.

Magnetic resonance imaging of the wrist in early rheumatoid arthritis reveals a high prevalence of erosions at four months after symptom onset

OBJECTIVES

To evaluate the role of magnetic resonance imaging (MRI) of the wrist in detecting early joint damage in patients with rheumatoid arthritis (RA).

METHODS

MRI was performed on 42 patients with early RA (median symptom duration of four months). Scans were scored separately by two musculoskeletal radiologists using a newly devised scoring system, which was validated. MRI findings were compared with plain radiography, clinical measures, and HLA-DRB*01/04 genotyping.

RESULTS

Interobserver reliability for the overall MRI score was high (r = 0.81) as was intraobserver reliability (r = 0.94 for observer 1 and 0.81 for observer 2). There was more variation in scoring synovitis (interobserver reliability: r = 0.74). Erosions were detected in 45% of scans (19 of 42), compared with 15% of plain radiographs. The most common site for erosions was the capitate (39%), for synovitis the ulnar aspect of the radiocarpal joint, and for tendonitis, the extensor carpi ulnaris tendon. The total MRI score and MRI synovitis score correlated most significantly with C reactive protein (r = 0.40 and 0.42 respectively, p < 0.01). The MRI erosion score was highly correlated with MRI bone marrow oedema (r = 0.83) as well as the Ritchie score and disease activity score (r = 0.32, p < 0.05). HLA-DRB1*04 or *01 (shared epitope +ve) was found in 76% of patients; 84% of those with MRI erosions and 69% of those without (NS, p = 0.3).

CONCLUSIONS

A high proportion of RA patients develop MRI erosions very early in their disease, when plain radiography is frequently normal. MRI of the dominant wrist may identify those requiring early aggressive treatment.

TCRBV14S1 and rheumatoid arthritis revisited: abnormalities in the percentage of transcribed TCRBV14S1 family genes in PBMC from rheumatoid arthritis patients

The purpose of this study was to identify Vbeta gene families that are associated with rheumatoid arthritis (RA). A PCR-based assay was used to compare the Vbeta repertoire of unstimulated PBMC from 18 RA patients and 18 matched controls. The influence of an HLA-DRB1-binding peptide (HA307-319) on the Vbeta repertoire of PBMC in culture was compared in 11 RA patients and 10 controls. There was a larger variance in the percentage of BV14S1 transcripts in unstimulated PBMC from RA patients than from controls (p = 0.0003). The mean percentage of BV14S1 transcripts was higher in RA patients when prednisone-treated RA patients were excluded from the analysis (p = 0.0006). In vitro stimulation with the HA307-319 peptide increased the percentage of BV14S1 transcripts in PBMC from RA patients (+ 1.5 +/- 0.4%, p < 0.005) but not controls (+ 0.3 +/- 0.2%, ns), and the difference between RA patients and controls was significant (p = 0.03). In conclusion, there is an association between RA and the BV14S1 gene family in New Zealand patients.

Immunization with heat-killed Mycobacterium vaccae stimulates CD8+ cytotoxic T cells specific for macrophages infected with Mycobacterium tuberculosis

Immune responses to Mycobacterium tuberculosis are analyzed in mice which have been immunized with Mycobacterium vaccae to examine novel ways of altering protective immunity against M. tuberculosis. The spleen cells of mice immunized with M. vaccae proliferate and secrete gamma interferon (IFN-gamma) in response to challenge with live M. tuberculosis in vitro. Immunization with M. vaccae results in the generation of CD8+ T cells which kill syngeneic macrophages infected with M. tuberculosis. These effector cytotoxic T cells (CTL) are detectable in the spleen at 2 weeks after immunization with M. vaccae but cannot be found in splenocytes 3 to 6 weeks postimmunization. However, M. tuberculosis-specific CTL are revealed following restimulation in vitro with heat-killed M. vaccae or M. tuberculosis, consistent with the activation of memory cells. These CD8+ T cells secrete IFN-gamma and enhance the production of interleukin 12 when cocultured with M. tuberculosis-infected macrophages. It is suggested that CD8+ T cells with a cytokine secretion profile of the Tc1 class may themselves maintain the dominance of a Th1-type cytokine response following immunization with M. vaccae. Heat-killed M. vaccae deserves attention as an alternative to attenuated live mycobacterial vaccines.

Left ventricular function in scleroderma

Scleroderma affects the left heart directly and indirectly via the effects of systemic hypertension. Using transthoracic echocardiography, we evaluated 35 patients with scleroderma and compared them with matched control subjects. Compared with controls, there were no differences between left ventricular dimensions, wall thickness, calculated mass or fractional shortening. However, the left atrium was enlarged (P = 0.006) and the mitral deceleration time was prolonged (P = 0.0005) in patients with scleroderma; suggesting abnormal diastolic function. After adjusting for potential confounders, duration of Raynaud's was found to be an independent predictor of deceleration time (P = 0.04), E/A peak velocity ratio (P = 0.04), A peak velocity (P = 0.004) and A velocity time integral (P = 0.0001), all measures of diastolic function. This group of individuals with scleroderma have evidence of abnormal diastolic function of the left ventricle despite normal left ventricular size and systolic function, and in the absence of hypertrophy. This finding is independent of the use of vasoactive medications and history of systemic hypertension, and thus may be due to primary myocardial involvement by scleroderma. The tendency to abnormal diastolic function of the left ventricle correlated with the duration of Raynaud's phenomenon.

Repertoire of transcribed peripheral blood T-cell receptor beta chain variable-region genes in acute rheumatic fever

Patients with severe group A streptococcal infections have abnormalities in the Vbeta repertoire of peripheral blood T cells that are consistent with superantigen stimulation by cytoplasmic membrane proteins. The purpose of this study was to determine whether similar changes in Vbeta repertoire could be found for patients with acute rheumatic fever (ARF). The mean Vbeta repertoire of peripheral blood T cells in nine hospitalized ARF patients was similar to that of 34 controls and did not change during 6 months of follow-up in 6 of the ARF subjects. We were unable to detect changes in the Vbeta repertoire of peripheral blood T cells from patients with ARF that could be attributed to the influence of a superantigen.

The influence of a recombinant-HBsAg vaccine on the repertoire of transcribed T-cell receptor beta chain variable region genes in peripheral blood in humans

The purpose of this study was to determine whether in vivo changes in the repertoire of Tcr beta chain variable region (V beta) genes could be detected in peripheral blood mononuclear cells after immunization of humans with recombinant hepatitis B virus envelope protein (rHBsAg). We measured the percentage of Tcr RNA transcripts carrying each of 20 V beta genes in human PBMC before and after immunization with rHBsAg in Polynesians (8 non-immunized controls, 26 immunized subjects) and Europeans (9 non-immunized controls, 11 immunized subjects). The per cent of RNA transcripts containing V beta 7.4 family genes was increased in immunized vs control Polynesian (+ 1.6 +/- 0.5%) vs -1.1 +/- 0.3%, P = 0.0002) and European (+1.6 +/- 0.6% vs -0.1 +/- 0.5%, P = 0.05) subjects at 48 h and 28 h post-immunization, respectively. No changes in V beta repertoire were found after 48 h in either race. Thus, there is a transient increase in frequency of T cells with Tcr containing V beta 7.4 family genes within 48 h of an immunization containing rHBsAg in humans. There are a number of explanations for this finding, including the possibility that V beta 7.4 gene family products may be preferentially involved in the primary immune response to HBsAg.

The influence of a maternal chronic hepatitis B virus infection on the repertoire of transcribed T-cell receptor beta chain variable region genes in human cord blood

We used an anchor polymerase chain reaction method to compare the repertoires of transcribed T-cell receptor beta chain variable region (V beta) genes in cord blood T cells from neonates of hepatitis B surface antigen (HBsAg) positive (n = 40) and HBsAg negative (n = 40) women. Fifteen of the HBsAg positive women were hepatitis B e antigen (HBeAg) positive, and 25 were HBeAg negative. The percentage of V beta 7.4 transcripts was lower in cord blood T cells from neonates of HBsAg-positive relative to HBsAg-negative women (9.7% +/- 0.5% vs. 12.7% +/- 0.6%, P = .002). The percent of V beta 5.1 transcripts was higher in cord blood T cells from neonates of HBeAg-positive relative to HBeAg-negative women (9.3% +/- 0.7% vs. 7.0% +/- 0.3%, P < .001). There were no correlations between neonatal maturity at birth and V beta repertoire. In summary, a maternal chronic hepatitis B virus (HBV) infection is associated with changes in the repertoire of transcribed T-cell receptor genes in neonatal cord blood T cells. It is possible that the T-cell response to the HBV is associated with a limited repertoire of V beta genes. The mechanism of vertical chronic HBV infection in human neonates may involve changes in the T-cell response to the virus that are induced in utero.

Peripheral blood T lymphocytes in systemic vasculitis: increased T cell receptor V beta 2 gene usage in microscopic polyarteritis

Antigen recognition by T lymphocytes is mediated by cell surface receptors T cell specificity depends on the variable, diversity and junctional (VDJ) regions of the alpha and beta polypeptide chains of the T cell receptor (TCR). The expression of the variable region genes of the beta chain (V beta) has been analysed to study the involvement of peripheral blood T cells in systemic vasculitis. RNA was extracted from peripheral blood lymphocytes of 12 patients with microscopic polyarteritis, 10 with Wegener's granulomatosis, six with unclassified vasculitis, and 28 healthy age- and sex-matched individuals. Complementary DNA was made from RNA and amplified by the anchored polymerase chain reaction (PCR) using redundant oligonucleotide primers for the TCR V beta genes. To determine if the dominant usage of a V beta gene family reflected the presence of particular T cell clones, cDNA was amplified with primers for the specific V beta gene family. The product was screened for sequence homogeneity by single-stranded conformational polymorphism (SSCP) and cloned to sequence the adjoining TCR (D beta) J beta region. A significant increase in the mean percentage expression of the V beta 2.1 gene was seen in vasculitis patients (11.4 + 1.0% (mean + s.e.m.)) compared with controls (6.6 + 0.6%; P < 0.003). The most marked increase was seen in microscopic polyarteritis (13.9 + 1.7%; P < 0.0001). There were also increases in the expression of V beta 3, 13 and 14 in peripheral blood of vasculitis patients compared with controls. SSCP analysis of V beta 2.1 amplified products indicated the presence of oligoclonal bands in a smaller proportion of patients (8/27) than controls (12/28). There was no strong evidence for the conservation of the TCR V beta 2.1 junctional region sequence data from a sample group of three patients with oligoclonal bands. Thus, a subset of patients with systemic vasculitis, particularly those with microscopic polyarteritis, have increased TCR V beta 2.1 gene expression in their peripheral blood T cell repertoire. As superantigens binding V beta 2.1 are postulated to activate T cells with diverse CDR3 sequences, it is proposed that a superantigen is involved in the immunopathogenesis of vasculitis.

Search for linkage disequilibrium between alleles in the T cell receptor alpha and beta chain loci and susceptibility to rheumatic fever

A population-based linkage disequilibrium study was conducted to search for associations between alleles in T cell receptor alpha and beta chain polymorphic loci and susceptibility to rheumatic fever. The allele frequencies of four T cell receptor locus restriction fragment length polymorphisms were measured in 47 European and 51 Maori subjects with a history of rheumatic fever. These allele frequencies were compared to the allele frequencies in three or four independently recruited, race-matched control groups totalling 125 Europeans and 117 Maoris with no history of rheumatic fever. The polymorphisms studied were (locus/enzyme/probe) C alpha/Taq1/Y14, V alpha/Taq1/Y14, V beta 7/BAMHI/V beta 7.4 and V beta 8/BAMHI/V beta 8.1. There was no evidence for linkage disequilibrium between rheumatic fever and these Tcr alleles in either the Maori or European subjects.

Natural killer cell function and expression of beta 7 integrin in psoriatic arthritis

OBJECTIVE

To examine the cytotoxic activity of natural killer (NK) cells from peripheral blood (PB) and synovial fluid (SF) of patients with psoriatic arthritis (PsA). The influence of selected inflammatory mediators on the cytolytic function and integrin expression of NK cells was also studied.

METHODS

Paired samples of PB and SF lymphocytes (PBL and SFL) were obtained from 8 patients with PsA for comparison of NK activity between PBL and SFL. In 6 patients the phenotype of NK cells was determined by flow cytometry using monoclonal antibodies (Mab) to natural killer associated antigen (NKH-1) and the beta 7 integrin, HML-1 (human mucosal lymphocyte adhesion molecule).

RESULTS

NK activity of PB samples was significantly greater than paired SF (p = 0.015). SF NK activity was enhanced by overnight culture with interleukin 2 (IL-2) (p < 0.05). A trend towards reduction of NK activity by prostaglandin E2 (PGE2) was noted (p = 0.06) whereas interleukin 6 (IL-6) and indomethacin had no significant effect. NK activity did not correlate with the percentage of NK cells in PB or SF. However, all SF samples contained a greater proportion of monocytes than PB samples. The expression of HML-1 on NK cells correlated with expression HML-1 on CD3+ cells (r = 0.82) and was greater in SF than PB in PsA and RA patients. Effects of IL-2 on HML-1 expression by NK cells were variable in the 3 patients studied.

CONCLUSION

In PsA, HML-1 is an activation marker on NK cells. IL-2 expands or maintains the population of HML-1/NKH1 positive cells and increases NK cytolytic activity. However, cytolytic activity of activated NK cells may be inhibited by monocyte derived PGE2.

The effect of prostaglandin E2 and indomethacin on the cytotoxic response to mycobacterial antigens

The effect of prostaglandin E2 and indomethacin on the generation of cytotoxic T-lymphocytes in response to Mycobacterium tuberculosis (MTB) antigens was compared between healthy controls and rheumatoid arthritis patients. Peripheral blood mononuclear cells (PBMC) from 16 healthy individuals and 15 RA patients were stimulated for 7 days with an irradiated, sonicated preparation of MTB in the presence or absence of PGE2 or indomethacin and assayed for cytotoxic activity on autologous target cells prepulsed with MTB. The mean cytotoxic activity generated was lower in patients than in controls. Exogenous PGE2 suppressed the cytotoxicity directed against MTB pulsed targets in 12 of 16 controls, but in only 1 of 11 patients. Indomethacin enhanced this cytotoxicity in only 2 of 16 controls but in 6 of 10 RA patients. When effector cells were derived from the synovial fluid, PGE2 again had no effect and indomethacin enhanced the cytotoxicity. Our data suggest that the depressed cytotoxic response of RA patients to MTB may be due to the production of endogenous PGE2. Cyclooxygenase inhibitors commonly used in the treatment of RA may influence MTB induced cytotoxicity in patients. In addition to their anti-inflammatory effects within the joint, non-steroidal anti-inflammatory drugs may potentially enhance cytotoxic reactions which are induced by antigens, such as MTB cross-reactive heat shock proteins.

Lymphocyte responses to DR1/4 restricted peptides in rheumatoid arthritis

OBJECTIVE

To determine whether analog and unrelated DR1/4 binding peptides alter DR1/4 restricted responses of peripheral blood lymphocytes (PBL) from patients with rheumatoid arthritis (RA).

METHODS

PBL from 25 patients with RA and 12 healthy controls were cultured with DR1/4 restricted peptides of the influenza haemagglutinin, amino acids 307-319 (HA) and matrix proteins, amino acids 17-29 (IM). Responses were determined by 3H-thymidine uptake proliferation assays and limiting dilution analysis. Competitor peptides were analogs HA-R312 and HA-K313 differing from HA by one amino acid at the 312 or 313 position respectively or unrelated peptides which bind to DR1/4.

RESULTS

The responses of eight patients with RA to the two stimulatory influenza peptides did not differ significantly from controls and this was confirmed by the frequency estimate of T cells in PBL which responded to HA (mean frequency: 1 in 9.0 x 10(4), n = 5, in DR1/4+ RA patients, 1 in 7.6 x 10(4), n = 5, in DR1/4+ healthy controls). DR1/4 binding analogs of the HA peptide inhibited HA specific peptide responses of PBL from patients with RA and controls. Inhibition was also detected with unrelated peptides which bind to DR1/4 but to which the individual did not respond.

CONCLUSION

Similar responses to two DR1/4 restricted peptides were observed in patients with RA and controls. Both antigen analog- and unrelated peptide-major histocompatibility complexes (MHC) can result in the inhibition of antigen specific responses in multi-clonal human lymphocyte populations. However, an analog peptide may be stimulatory in some individuals. These results provide some initial data for the development of a rational approach to MHC-specific immunomodulation in rheumatoid arthritis.

T cell receptor polymorphisms in Caucasians and Polynesians

The purpose of this study was to find genetic polymorphisms that might be useful in studies of Polynesian-Caucasian racial admixture and Polynesian disease susceptibility. The allele frequencies of six T cell receptor locus RFLP were measured in 73 Caucasians and two Polynesian ethnic groups comprising 86 Maoris and 95 Samoans. The RFLP studied were (locus/enzyme/probe): C alpha/Taq1/Y14, V alpha/Taq1/Y14, C beta/BglII/Y35, C gamma/Pvu II/HGP02, V beta 7/BamHI/V beta 7.4 and V beta 8/Bam HI/V beta 8.1. Racial differences in allele frequency were present with all six RFLP (P < 0.001). The allele frequencies of the V alpha/Taq1/Y14 and the V beta 7/BamHI/7.4 RFLP were similar in the two Polynesian groups, both of which differed from the Caucasians. The 1.4 kb allele of the V alpha/Taq1/Y14 RFLP and the 8.0 kb allele of the V beta 7/BamHI/7.4 RFLP were present in low frequency in both Polynesian groups compared to the Caucasian group, consistent with a gene flow effect. These alleles may be useful in studies of Caucasian-Polynesian racial admixture.