Radiofrequency catheter ablation for AV nodal reentrant tachycardia associated with persistent left superior vena cava

Slow AV nodal pathway ablation using RF is highly effective for patients with refractory AV nodal reentrant tachycardia (AVNRT). We report three catheter ablation cases using RF current in patients associated with persistent left superior vena cava (PLSVC). Three patients with drug refractory AVNRT of common variety were involved in this study. An electrode catheter introduced through the left subclavian vein inserted directly into the coronary sinus, a typical anatomical finding of PLSVC. The ablation procedure was initially performed at the posteroinferior region of Koch's triangle. A slow pathway potential could not be found from that area; nonsustained junctional tachycardia (NSJT) did not occur during the delivery of RF current; there was failure to eliminate slow AV nodal pathway conduction. The catheter then was moved into the bed of the proximal portion of the markedly enlarged coronary sinus. A slow AV nodal pathway potential was recorded through the ablation catheter, and the delivery of RF current caused NSJT in two patients. Complete elimination of slow AV nodal pathway conduction was accomplished in these two patients by this method. No adverse effects were provoked by this procedure. Catheter ablation of the slow AV nodal pathway guided by a slow pathway potential and the appearance of NSJT was feasible and safe in the area of the coronary sinus ostium in patients associated with PLSVC.

Isolation from fetal bovine serum of a fragment b of complement factor B-like protein improving a long-term survival of human endothelial cells

It is known that serum is a most important factor supporting cell survival and growth. Particularly, the deprivation of serum would result in the death of human endothelial cell. Our previous paper reported an endothelial cell-viability maintaining factor (EC-VMFa) purified from fetal bovine serum and identified as an apolipoprotein. In the present further study, it is demonstrated that another potent serum factor (refer as EC-VMFb) is also possessed of the endothelial cell-viability maintaining activity, improving a long-term survival of human endothelial cells in serum-free medium. EC-VMFb has a molecular weight of 66,000 (reduced and nonreduced), pI of 4.5 and has been identified as fragment b of complement factor B (Bb)-like protein by amino-terminal amino acid sequence.

Effects of mechanical stimulation in measurement of thermal pain threshold

The improved thermal dolorimeter developed by Fukumoto has made it easy to measure thermal pain thresholds, but mechanical stimulations may be included as the probe is pressed into the skin. In order to evaluate these effects of mechanical stimulation on the improved thermal dolorimeter, the pain threshold temperatures were measured by a probe pressed to the human skin surface with weighting loads from 0.5 to 2.5 kgf. The loads of 2.0-2.5 kgf felt invasive to 8 of the 12 subjects, i.e., they experienced pain and numbness. The threshold temperature of one of these subjects, who developed water blisters around load-added area on the skin after the experiments, exceeded 50 degrees C. The result that no significant difference could be found among the thresholds at the loads of over 2.0 kgf suggests the load of less than 2.0 kgf should be kept to execute proper experiments. In order to investigate other effects on thermal property by compressing, the blood flow was measured when the skin was compressed and three dimensional heat transfer simulations were conducted. The results of the simulations demonstrated that the temperatures of the heat source which were measurable in practice differed approximately 1 to 2 degrees C from the true thresholds. The velocity of heating is also increased and subjects will be given stronger feelings of heating.

[A case of primary HIV-1 infection]

A previously healthy 28 year old Japanese man came to us with a genital ulcer which appeared 13 days before admission to our hospital. He had subsequently fever (40 degrees C), arthralgia, a sore throat and oral aphtha 6 days before admission. He had a history of sexual contact with a female commercial sex worker one week before his illness. On the day of admission, he had shallow ulcers on the lip, tongue and penis. Initial laboratory test included leukopenia and thrombocytopenia. His fever abated 3 days after admission. His condition and bicytopenia recovered completely after 12 days of admission. Although, his serum HIV-1 antibody was negative when he was admitted, 3 months later the antibody was seroconverted. And p24 antigen and HIV-1 RNA of stocked serum were positive. Diagnosis of primary HIV-1 infection was made. Recently, HIV-1 infection has been increasing in Japan. Consideration of this disease in differential diagnosis of acute febrile illness is necessary.

Effect of heat-induced structural perturbation of secondary and tertiary structures on the chaperone activity of alpha-crystallin

alpha-Crystallin, a major protein of the lens, is known to have chaperone activity to protect other proteins against thermal aggregation. Heat-induced structural change of alpha-crystallin was previously shown to increase its chaperone activity. In this report, we studied the thermal reversibility of alpha-crystallin and the effect of change in secondary structure on its chaperone function in vitro. The heat-induced conformational changes in the aromatic region of near-UV CD spectra showed only a small degree of reversibility. The structural transitions from 50 to 70 degrees C were largely reversible if the incubation time was short. However, the protective ability to inhibit thermal aggregation of alcohol dehydrogenase by alpha-crystallin was essentially similar at 48 and 70 degrees C. Under long-term heating at high temperatures, there was a time-dependent irreversibility of structural change in alpha-crystallin as revealed by CD spectroscopy. Such denatured alpha-crystallin by long-term heating can still preserve its ability to prevent UV-induced aggregation of gamma-crystallin at room temperature, indicating relatively little effect of heat-induced changes in secondary structure on the chaperone activity of alpha-crystallin.

[Intrathecal midazolam attenuates renal sympathetic nerve activity in rabbits]

We hypothetized that intrathecal (IT) midazolam (M) affects renal sympathetic nerve activity (RSNA) via benzodiazepine receptors (BZR) at the spinal cord. Under alpha-chloralose anesthesia, 26 rabbits underwent surgical procedures for the cannulation to femoral artery and vein for measuring blood pressure and infusing lactated Ringer solution, respectively. Intrathecal cannulation was performed at the 7th thoracic vertebral level. RSNA was recorded from the nerve raw between the renal artery and vein using a left flank incision. In the neuraxis-intact rabbits, IT administration of low dose M (0.50%) did not affect heart rate (HR), mean arterial pressure (MAP), and integrated RSNA (IRSNA). High concentration of M (0.5%) increased HR, decreased MAP and attenuated IRSNA significantly. In the sino-aortic denervated rabbits, IT administration of 0.5% M decreased MAP and IRSNA, but intravenous 0.2 flumazenil rapidly and significantly increased MAP and IRSNA. This finding suggests that the decrease in IRSNA followed by IT M derives from BZR. In conclusion, IT high concentration of M attenuated RSNA through BZR.

Sensitivity of rat cortical neurons in distinguishing taste qualities by individual and correlative activities

To examine the possibility that different taste qualities are represented by the correlative activity of cortical gustatory neurons, we made simultaneous recordings of neuron pairs during application of four basic tastes into the oral cavity of anesthetized rats and the following observations were made: (i) in 30 of 67 pairs of taste responsive neurons, peaks (troughs in a few cases) were produced in the cross-correlograms (CCs) during stimulation with some tastants; (ii) the correlative discharges occupied 6-8% of the total spikes discharged by individual neurons during taste stimulation and occurred, in a considerable number of cases, even during stimulation with tastants to which one or both of the component neurons of a pair were apparently non-responding (often sucrose and quinine); (iii) the number of tastants to which a neuron pair responded with a significant correlative activity was often greater than the number of tastants to which the component neurons of the same pair responded with significant changes in discharge rate; (iv) there was no significant difference between the correlative (formation of peaks or troughs in the CC) and individual (change in discharge rate of individual neurons) ways of coding in the sensitivity to distinguish between two taste qualities ranked to be adjacent on the basis of the number of spikes composing the response; and (v) the peaks or troughs appearing in two CCs during stimulations with two kinds of tastants were compared with regard to overlapping of their delay ranges and widths. The spikes in the non-overlapping portion of each peak (suppressed spike number in the case of troughs) are supposed to be able to contribute to two-taste discrimination: the correlated discharges occurring with a delay time that corresponds to the overlapping portion can in no way be judged differently, but the spikes falling in the non-overlapping portion may contribute to the differentiation. The ratio of the non-overlapping portion to the entire peak (or trough) was 0.35 on average. It is concluded that temporal coding of taste qualities seems to operate effectively in the gustatory cortex.

Minimum alveolar concentration of sevoflurane for tracheal extubation in children

BACKGROUND

One advantage of tracheal extubation during deep anaesthesia is that respiratory complications are reduced. Sevoflurane is a suitable anaesthetic agent for children. This study was conducted to determine the minimum alveolar concentration of sevoflurane required to prevent cough or movement during and after tracheal extubation (MACextubation).

METHODS

We studied 30 nonpremedicated children, aged 2-10 yr, undergoing plastic surgery. They were allocated randomly to five groups (end-tidal sevoflurane concentrations: 2.0, 2.5, 3.0, 3.5, 4.0%). After surgery, 60% nitrous oxide was discontinued and the target concentration of sevoflurane was maintained for at least 10 min in 100% oxygen, then the trachea was extubated to determine MACextubation. Logistic regression was used to estimate MACextubation of sevoflurane.

RESULTS

MACextubation was 2.3 (0.2; standard error)% (95% confidence limits: 1.2% and 2.7%).

CONCLUSIONS

Tracheal extubation in 50% of anaesthetized children age 2-10 yr may be accomplished without coughing or moving at 2.3% end-tidal concentration of sevoflurane.

Synthesis and antimetastatic activity of L-iduronic acid-type 1-N-iminosugars

L-Iduronic acid-type 1-N-iminosugars, (3R,4S,5R,6R)- and (3R,4S,5S,6R)-6-acetamido-4-amino-5-hydroxypiperidine-3-carboxylic acid (6 and 7, respectively), (3R,4S,5R,6R)-6-acetamido-4- guanidino-5-hydroxypiperidine-3-carboxylic acid (8), and (3R,4S,5R,6R)-4-amino- and -guanidino-5-hydroxy-6-(trifluoroacetamido) piperidine-3-carboxylic acid (9 and 10, respectively), were synthesized from siastatin B (1), isolated from Streptomyces culture, by the intramolecular Michael addition of O-imidate to its alpha,beta-unsaturated ester through cis oxiamination as a key step. Preincubation of B16 BL6 cells with these compounds inhibited invasion of the cells through reconstituted basement membranes. Pulmonary metastasis of B16 BL6 cells in mice was remarkably inhibited by pretreatment of the cells with these compounds in culture.

Postnatal ontogeny of the thyrotropin-releasing hormone receptor messenger ribonucleic acids in the rat forebrain

Postnatal developmental change of the thyrotropin-releasing hormone receptors (TRHR) in the rat forebrain was investigated using TRH binding assays and Northern blot analyses from postnatal day 8 to the age of 2 years. TRH binding assays, with [3H]MeHisTRH as the radioactive ligand, demonstrated that the binding capacity in the forebrain was lowest at postnatal day 8 and increased to a maximum level at postnatal day 20. The TRH binding significantly decreased to adult levels between days 20 and 35, and no significant change was observed thereafter. Northern blot analysis, with a 32P-labeled TRHR cRNA probe, revealed that expression of the TRHR gene in the forebrain was not detectable on day 8 after birth, whereas apparent gene expression could be detected in the anterior pituitary. In contrast to the binding capacities, TRHR mRNA levels were very low until postnatal day 20, and increased significantly between days 20 and 35. No significant alteration in mRNA levels was observed after day 35. These results indicated that: (1) TRH binding capacities in the forebrain increased to a maximum levels between the second and third postnatal week and thereafter decreased to adult level, (2) the levels of TRHR mRNA and the TRH-binding capacities did not correlate in that period, suggesting that the TRHR number in the immature forebrain might be regulated by a posttranscriptional mechanism, and (3) expression of the TRHR gene in the forebrain and pituitary seemed to be regulated differentially during development.

The dmsR gene encoding a dimethyl sulfoxide-responsive regulator for expression of dmsCBA (dimethyl sulfoxide respiration genes) in Rhodobacter sphaeroides f. sp. denitrificans

Upstream of the dmsCBA genes encoding dimethyl sulfoxide (DMSO) reductase in the phototrophic bacterium Rhodobacter sphaeroides f. sp. denitrificans, there was found one gene (referred to dmsR) which encoded a protein composed of 232 amino acid residues and was divergently transcribed from the dmsCBA genes. The deduced amino acid sequence was homologous to the OmpR subfamily of response regulators in two-component systems for transcriptional regulation. The encoded protein DmsR was shown to bind to a DNA fragment containing the four direct repeats of a decameric nucleotide motif located between the dmsR and dmsCBA genes. The DNA-binding activity of DmsR was observed when the organism was grown anaerobically in the presence of DMSO. A dmsR-defected mutant strain showed no synthesis of DMSO reductase. These results indicate that the dmsR gene product acts as a positive regulator for expression of the dmsCBA genes in response to DMSO under anaerobic growth conditions.

Arrestins expressed in killifish photoreceptor cells

Two kinds of cDNA fragments (KfhArr-R and KfhArr-C) encoding the putative arrestins of killifish, Oryzias latipes, were isolated. The distributions of these transcripts were investigated by in situ hybridization, and it was demonstrated that KfhArr-R and KfhArr-C are expressed in, respectively, rod and all four types of cone cells. The deduced amino acid sequences of KfhArr-R and KfhArr-C are closely related to human S-antigen (rod arrestin) and X-arrestin (cone arrestin), respectively. Phylogenetic analysis of arrestin sequences suggests that vertebrate visual arrestins form a single cluster distinct from other arrestins and diverged to form rod and cone subtypes before the divergence between teleosts and tetrapods. It is speculated that the divergence pattern of vertebrate visual arrestins may prove to be reflected in the divergence of the proteins participating in the respective phototransduction cascades.

Loss of the xeroderma pigmentosum group A gene (XPA) enhances apoptosis of cultured cerebellar neurons induced by UV but not by low-K+ medium

To study the involvement of the xeroderma pigmentosum group A gene (XPA) in neuronal apoptosis, we cultured cerebellar neurons from mice lacking XPA gene (XPA-/-) and induced apoptosis by exposure to UV irradiation or medium containing a low concentration of potassium (low-K+ medium). When cerebellar neurons from postnatal days 15-16 wild-type mice were treated with UV irradiation, apoptotic neuronal death was observed after 24-48 h. About 60% of neurons survived 48 h after UV irradiation at a dose of 5 J/m2. On the other hand, neurons from XPA-/- mice showed a significantly increased vulnerability to UV irradiation, and >90% of neurons died 48 h after UV irradiation at a dose of 5 J/m2. In contrast, low-K+ medium induced apoptosis of neurons from mice of each genotype with the same kinetics. These results suggest that the XPA gene is involved in neuronal DNA repair and that it thereby influences apoptosis induced by DNA damage in cultured cerebellar neurons.

[A case of fulminant hepatitis caused by antiandrogen, flutamide in a patient with prostate cancer]

Luteinizing hormone-releasing hormone analogue, 3.6 mg goserelin acetate and flutamide, 375 mg per day were used to treat metastatic prostate cancer in a 66-year-old male. Marked increase in serum aminotransferases and total bilirubin levels was noted after 7 weeks of treatment. The enzyme levels returned to normal at 2 months following discontinuation of the treatment. Though incidences of severe hepatotoxicity are rare (0.003-0.18%), cases of flutamide-induced death have been reported. Careful monitoring of patients is mandatory while administering flutamide.

Adenovirus isolation from spleen lymphocytes of apparently healthy pigs

A polyethylene glycol treatment was given to fuse KSEK6 cells, an established cell line derived from porcine embryo kidney, with the lymphocytes, separated from spleens of 35 apparently healthy slaughtered pigs. Eight cytopathic virus strains were isolated from the lymphocytes of these pigs. Two virus strains were isolated by inoculating the spleen tissue homogenates to KSEK6 monolayer cultures. All of viruses were identified as porcine adenoviruses according to their physicochemical, serological and immunological properties. One of these virus strains was serologically proved to be independent from six serotypes of porcine adenoviruses ever known. The electrophoretic property of viral DNA of this strain was indicated to be different from those of other reference porcine adenoviruses. This means the presence of a 7th serotype in porcine adenoviruses.

Changes in electrophysiological and mechanical responses of the rat papillary muscle to alpha- and beta-agonist in streptozotocin-induced diabetes

To clarify the changes occurring in diabetic animals in the responsiveness of the myocardium to alpha 1- and beta-adrenoceptor agonists, we examined both alpha- and beta-adrenoceptor-mediated electrophysiological and mechanical responses in the depolarized right ventricular papillary muscle of streptozotocin (STZ) induced diabetic rats and age-matched controls. Both methoxamine (10(-7)-10(-4) M) and isoproterenol (10(-9)-10(-6) M) enhanced the slow response action potential in a concentration-department manner. The amplitude and the APD50 (time required for 50% repolarization) of the methoxamine-induced slow response action potential were both markedly increased in STZ-induced diabetic rats in comparison with control rats, whereas those of the isoproterenol-induced slow response were significantly decreased. The methoxamine-induced contraction in depolarized muscle was slightly but not significantly increased in STZ-induced diabetic rats, whereas the isoproterenol-induced contractile response was significantly attenuated. The maximum number of binding sites (Bmax) for [3H]dihydroalprenolol and for [3H]prazosin were both significantly decreased in diabetic rats, compared with age-matched control rats, without any change in the affinity constants. The slow response action potential induced by methoxamine but not isoproterenol was attenuated by IAP (islet-activating factor) treatment (50 micrograms/kg, i.v. for 3 days). These results suggest that an alpha-adrenoceptor-mediated electrophysiological response is unmasked when the beta-adrenoceptor-mediated response is desensitized in the papillary muscle of STZ-induced diabetic rats.

Eccentric simple bone cysts of the femoral neck in adults

The purpose of this communication is to describe atypical simple bone cysts of the femoral neck seen in adult patients. Two patients, aged 56 and 49, having cystic lesions which did not conform to a typical simple bone cyst, are reported. Common features including eccentric location, and thick lining tissue and sclerotic margin are not those of typical simple bone cysts seen in children. Local mechanical characteristics might be related to the atypical presentations.

[Application of Internet technology in public health]

Recent advances in telecommunication technology have been enormous. Application of this technology in public health has the potential to markedly improve global health through better surveillance and information systems. With this assumption the GHNet was established in 1994 by representatives from academia, WHO, Pan American Health Organization, the World Bank, NASA, IBM, and AT & T. The GHNet consists of seven components: 1) promotion of networking with the Internet among people in public health; 2) disease tele-monitoring; 3) distance learning system with the internet; 4) connection of non-governmental health organizations; 5) training cyberdocs who are educated in both public health and telecommunications; 6) establishment of an electronic scientific research server; and 7) a home page on the World Wide Web (WWW). In order to effectively incorporate the Internet into the field, connectivity and knowing how to use it are of critical concern. More and more facilities are connected to the Internet in Japan. However, few courses teaching how to utilize the Internet are provided for people in this field. An Internet training course for people in public health was held as joint venture of the World Health Organization (WHO) and the Global Health Network (GHNet) on October 31, 1996, at the 55th Annual Meeting of Japanese Society of Public Health. Most of the participants for the course were from local public health departments and very few had previous experience with the Internet before the course. During this course participants learned how to use e-mail, how to find health resources on the WWW, how to construct a home page, and how the Internet could be utilized to improve public health, with their computers actually hooked to the Internet. From this experience, we found that this kind of course is feasible and beneficial and hope that this course would serve as a model for training people in public health.

[Emergent mitral valve replacement in the second trimester of pregnancy]

A 28-year-old woman with heart failure was hospitalized at 21 weeks of gestation. Nine years previously mitral regurgitation was diagnosed, and she underwent mitral valve replacement with a Carpentier-Edwards pericardial valve. Echocardiography revealed primary tissue failure of the mitral prosthesis. Emergent mitral valve replacement was performed. Normothermic high-flow high-pressure pulsatile perfusion was performed during cardiopulmonary bypass. Fetal heart rate was monitored, and it remained above 150 bpm throughout the operation. No bradycardia was observed. The degenerated prosthetic valve was replaced with another Carpentier-Edwards pericardial valve to ensure a safe pregnancy and delivery. Pregnancy was carried to term, and a healthy baby was delivered vaginally.

[Alteration of p15 and p16 gene in gastric cancer]

We analyzed p15 and p16 gene alterations in gastric cancer. Only MKN45 showed both homozygous deletions but other cell lines and all of tumor specimens did not show any alterations. Using RT-PCR analysis, decreased or no expression of the p16 gene was found in 1 of 7 cell lines (except MKN45) (14.2%) and in 8 of 20 tumors (40%), whereas no abnormalities of p15 gene expression were found. These results suggest that the p16 gene may correlate with tumorigenesis and tumor expansion due to decrease or loss of gene products in gastric cancer.

Endothelin-1 induces vasoconstriction and nitric oxide release via endothelin ET(B) receptors in isolated perfused rat liver

Endothelin-1 (0.1, 1 and 10 nM) induced a significant increase in portal pressure and nitric oxide (NO) release in the isolated rat liver. The endothelin ET(B) receptor agonist, IRL 1620 (Suc-[Glu9,Ala(11,15)]endothelin-1-(8-21)) (0.1, 1 and 10 nM) also elicited a marked increase in portal pressure and NO release. The potency of endothelin-1 was higher than that of IRL 1620. The endothelin ET(A) receptor antagonist, BQ-123 (cyclo(-D-Trp-D-Asp-Pro-D-Val-Leu)) (1 and 10 microM), had no effect on the endothelin-1-induced change in portal pressure and NO current. In contrast, the endothelin ET(B) receptor antagonist, BQ-788 (N-cis-2,6-dimethylpiperidinocarbonyl-L-gamma-methyl-leucyl-D-1-++ +methoxycarbonyltryptophanyl-D-norleucine) (1 and 10 nM), attenuated the endothelin-1-induced change in portal pressure and NO current. Administration of N(G)-monomethyl-L-arginine (L-NMMA), a NO synthase inhibitor, completely abolished the endothelin-1- or IRL 1620-induced NO release. L-NMMA enhanced the increase in portal pressure and decrease in O2 consumption caused by endothelin-1. These results indicated that endothelin ET(B) receptors mediate both vasoconstriction and NO release and that NO plays a significant role in stabilizing microcirculation in isolated perfused rat liver.

[Pulmonary hemodynamics and long-term outcome in patients with chronic pulmonary thromboembolism and pulmonary hypertension]

We examined pulmonary hemodynamics and long-term outcome in 78 consecutive patients with chronic pulmonary thromboembolism and pulmonary hypertension. These patient's ages ranged from 19 to 75 years; the mean was 51.0 +/- 13.8 years and there was no difference in sex distribution. Mean pulmonary-artery pressure (PAm) was 44 +/- 14 mmHg and total pulmonary resistance (TPR) was 1138 +/- 634 dyne.sec.cm-5. Overall five-year survival was 58.4%, but in patients whose PAm was below 30 mmHg, the outcomes were better: all of these patients survived for at least 5 years. In patients whose PAm was above 30 mmHg, no correlation was found between the outcome and the magnitude of PAm. We divided the patients into four subgroups according to their TPR: 500 dyne.sec.cm-5 (TPR, 500 > or = TPR < 1000 dyne.sec.cm-5, 1000 < or = TPR < 1500 dyne.sec.cm-5, and 1500 dyne.sec.cm-5 < or = TPR. The five-year survivals in these groups were 100%, 88.9%, 52.4%, and 40.0%, respectively. Outcome correlated with the magnitude of TPR. TPR was useful for predicting the outcome of chronic pulmonary thromboembolism.

Enantioselective fluorination of organic molecules. I. Synthetic studies of the agents for electrophilic, enantioselective fluorination of carbanions

In order to develop novel methods for electrophilic and enantioselective fluorination of active methine compounds, preliminary experiments were carried out. The N-tosyl derivative 5 obtained from D-phenylglycine was fluorinated with FClO3 or diluted F2 gas to give the N-fluoro-N-tosyl derivative 6. N-tosyl- or N-mesyl-(S)-alpha-phenethylamine 7 or 8 was subjected to FClO3 fluorination to produce the corresponding N-fluoro derivative, 10 or 11, respectively. Enantioselective fluorination of some methine compounds was attempted employing the above N-fluoro agents. Best result was obtained when 2-benzyl-1-tetralone/KHMDS was treated with 10 to produce the fluorinated tetralone 17 in 53% yield with enantiomeric excess (ee) of 48%.

Interferon-gamma differentially regulates CD80 (B7-1) and CD86 (B7-2/B70) expression on human Langerhans cells

CD80 (B7-1) and CD86 (B7-2/B70) have recently been identified in cultured human Langerhans cells (LCs), although their role and regulatory properties remain unclear. We present our comparison of the expression of the molecules, mRNAs and the function between CD80 and CD86 in human LCs treated by interferon gamma (IFN-gamma). We examined the regulatory properties of CD80 and CD86 expression in human LCs pretreated with IFN-gamma. Flow cytometric analysis indicated that the mean fluorescence intensity of CD86 but not CD80 was enhanced. However, the percentage modulation of both CD80 and CD86 positive cells were significantly up-regulated in a dose-dependent manner, after 48-h culturing with IFN-gamma. The regulatory properties of CD80 and CD86 mRNA expressions in human LC were studied using polymerase chain reaction methods. We found that both CD80 and CD86 mRNA of enriched LCs following IFN-gamma pretreatment for 12 h were higher than those without pretreatment. We have demonstrated that the primary allogeneic mixed epidermal cell-lymphocyte reaction induced by human LCs treated by IFN-gamma increased in a dose-dependent manner. There was a 61.5% inhibition by anti-CD86 monoclonal antibody and a 32.5% inhibition by anti-CD80 monoclonal antibody. These data indicate that the CD80 and CD86 expression of human LCs may be differently regulated by IFN-gamma.