Human dendritic cells genetically engineered to express a melanoma polyepitope DNA vaccine induce multiple cytotoxic T-cell responses

PURPOSE

To assess the therapeutic potential of a melanoma polyepitope vaccine in human cells. Polyepitope DNA vaccines encoding T-cell epitopes have been demonstrated in murine systems to generate multiple cytotoxic T-cell responses to different antigens. Here, for the first time we demonstrate the ability of a melanoma polyepitope to stimulate lymphocytes from normal human donors to simultaneously generate multiple antigen-specific responses.

EXPERIMENTAL DESIGN

Human dendritic cells (DC), transduced with a melanoma-polyepitope cDNA, were used to activate autologous lymphocytes from naïve donors as an in vitro model of DNA vaccination. Lymphocytes were primed with polyepitope or mock-transduced DC, boosted with peptide, then measured for antigen-specific cytotoxicity.

RESULTS

Lymphocytes primed with polyepitope-transduced DC and boosted with peptide generated multiple cytotoxic responses. By contrast lymphocytes primed with mock-transfected DCs and boosted with peptide gave no specific cytotoxicity. However, when lymphocytes were repeatedly stimulated with polyepitope-transduced DCs immunodominance was seen with CTLs being generated to only one epitope, MART(27-35).

CONCLUSIONS

We show in a human system that a melanoma polyepitope primes CTL to multiple epitopes. However, repeated stimulation by the polyepitope restricts the response to only the MART1 epitope. Thus, although polyepitope vaccines are an effective way of priming multiple naïve T-cell responses, continual boosting with polyepitope vaccines may, as a result of immunodominance, restrict the CTL. These findings have important implications for the use of DNA polyepitope vaccines in cancer immunotherapy.

The COP9/signalosome complex is conserved in fission yeast and has a role in S phase

The COP9/signalosome complex is conserved from plant to mammalian cells. In Arabidopsis, it regulates the nuclear abundance of COP1, a transcriptional repressor of photomorphogenic development [1] [2]. All COP (constitutive photomorphogenesis) mutants inappropriately express genes that are normally repressed in the dark. Eight subunits (Sgn1-Sgn8) of the homologous mammalian complex have been purified [3] [4]. Several of these have been previously identified through genetic or protein interaction screens. No coherent model for COP9/signalosome function has yet emerged, but a relationship with cell-cycle progression by transcriptional regulation, protein localisation or protein stability is possible. Interestingly, the COP9/signalosome subunits possess domain homology to subunits of the proteasome regulatory lid complex [5] [6]. Database searches indicate that only Sgn5/JAB1 is present in Saccharomyces cerevisiae, precluding genetic analysis of the complex in cell-cycle regulation. Here we identify a subunit of the signalosome in the fission yeast Schizosaccharomyces pombe through an analysis of the DNA-integrity checkpoint. We provide evidence for the conservation of the COP9/signalosome complex in fission yeast and demonstrate that it functions during S-phase progression.

Diagnosis of intrauterine growth retardation as a two-step process with morphometric ultrasound and Doppler umbilical artery velocimetry

Ultrasound and Doppler umbilical artery velocimetry have been used to diagnose the small-for-gestational-age (SGA) fetus. Both techniques are relatively inefficient for this diagnosis. The aim of the present study was to see whether their serial use improved diagnostic accuracy. Forty women with an ultrasound diagnosis of SGA within three weeks of delivery were studied with velocimetry, and the outcome was evaluated. Diagnostic accuracy was improved from 65% by ultrasonography alone to 92% by the addition of an abnormal umbilical artery waveform (P < .02). An abnormal waveform was associated with an adverse outcome in 62%, compared to 14% with normal velocimetry (P < .01). The majority of small fetuses have a normal outcome. The combination of ultrasonography and velocimetry improved diagnostic accuracy and identified those small fetuses truly at risk.

[Torsades de pointes and prolongation of the duration of QT interval after injection of droperidol]

Following a case of torsades de pointe (TDP) after the injection of droperidol (D), the authors studied the electrocardiographic variations caused by the drug. Fifty five unselected patients under the same conditions (general anesthesia) were given D (0.25 mg/kg IV). Significant prolongation of the QT interval was seen in 70% of cases by the end of the first minute. QT interval and the ratio of QTm (measured) over QTt increased from 387 +/- 34 ms to 423 +/- 37 ms (p less than 0.0001) and from 1.06 +/- 0.08 to 1.28 +/- 0.1 (p less than 0.001) respectively. These changes could favourise the onset of TDP. Although exceptional in terms of the extensive use of the neuroleptic in question, this possibility indicates the need for monitoring of the duration of QT before and during treatment with droperidol and for prescription of the drug to be avoided in circumstances known to be propitious to this arrhythmia (bradycardia, hypokalemia, anti-arrhythmic drugs).

Medical treatment of residual ectopic pregnancy: RU 486 and methotrexate

A patient with residual ectopic pregnancy after salpingostomy was treated with the anti-P RU 486. This did not result in lowered hCG levels, which subsequently resolved after treatment with methotrexate.

[Electrophysiologic basis of the anti-arrhythmic action of amiodarone in man]

The aim of this study was to analyse the effect of an intra-atrial injection of 5 mg/kg of amiodarone on the heart rate, the A-V conducting pathways, and the right atrium and ventricle of 23 patients. By recording the potentials in the bundle of His, it was possible to measure the nodal A-V conduction time (A-H interval) and the conduction time below the bundle of His (H-V interval) during atrial pacemaking. The refractory periods were calculated by the stimulus-test method. The results were subjected to statistical analysis using Student's test. They may be summarised as follows: - slowing of the sinus rhythm; - depressed conduction in the A-V node, but without any effect on the speed of conduction infranodally; - an increase in the atrial effective refractory period; - persistant lengthening of both the effective and the functional refractory periods of the A-V node; - an increase in the relative refractory period in the His-Purkinje system, and in the effective refractory period of the ventricle. These findings throw light on the mechanism of the anti-arrhythmic action of amiodarone in man.

[Electrophysiologic effects of amiodarone in Wolf-Parkinson-White syndrome]

Eight patients with WPW syndrome were catheterised and, during the course of this investigation, the electrophysiological effects of amiodarone were assessed. By registering the potentials of the bundle of His and by using the stimulus-test technique, we were able to measure the refractory periods of the atrium and of the normal and accessory conducting pathways both before and during the first 40 minutes after an intra-atrial injection of 5 mg/kg of amiodarone chlorhydrate. The action of the conduction time was also studied. In the five cases in which we were able to measure it, the effective refractory period of the abnormal pathway increased, which led in two instances to the temporary suppression of all pre-excitation. At the same time, it was repeatedly found that the refractory periods of the A-V node were increased: the effective refractory period in 3/3 cases, and the functional refractory period in 2/2 cases. The effective refractory period of the right atrium was increased in 5 cases, and did not change in the others. The intranodal conduction time (A-H- interval) was always increased after amiodarone. Finally, in three patients runs of reciprocal tachycardia could be initiated by premature atrial stimulation. In one case, this was no longer possible after amiodarone. In the other two cases, although the attacks could still be brought on, they were slower because of the lengthening of the A-H interval. These findings explain why amiodarone is effective in controlling the tachycardia of WPW syndrome.

[Study of the electrophysiological properties of bretylium tosylate in man]

The electrophysiological changes induced by bretylium tosylate have been studied in 22 patients during the 45 minutes following the intra-atrial injection of the drug at the dose of 5 mg/kg. The potential in the bundle of His was measured, and the stimulus-test method used to determine the refractory period. The results were subjected to Student's test. The sinus rate increased after bretylium. The A-V nodal conduction time (A-H interval) and infra hisian conduction time (HV interval), evaluated at the same imposed frequency, were not affected. The functional refractory period of the A-Vnode was decreased. The relative refractory period of the His-Purkinje system was increased. Finally, the right auricle showed an increase in its effective refractory period, while that of the ventricle remained unchanged. This study suggests that the electrophysiological effects of bretylium are due both to direct action at the cellular level and to sympathetic activity.

[Significance of spontaneous reduction of long term auricular fibrillation. Apropos of a case followed by subtotal auricular paralysis]

The authors report the case of a female patient with mitro-aortic valve disease, whose atrial fibrillation had been recorded over a period of 13 years. There was then a conversion to sinus rhythm, followed by the appearance of a junctional rhythm with retrograde atrial conduction. Intracavitory investigation revealed that the electrical activity of the right atrium could be recorded only from a limited area, and that atrial stimulation was effective only over that area. This subtotal atrial paralysis suggests that the spontaneous conversion from atrial fibrillation was a sign of deterioration in the condition rather than of a "paradoxical improvement".

Reciprocal rhythm in patients with normal electrocardiogram: Evidence for dual conduction pathways

The present study refers to six patients in whom an A-V reciprocal rhythm could be documented; in four cases it took the form of sustained tachycardia. None of the patients showed any ECG feature of ventricular pre-excitation (PR interval of more than 0.12 sec. and normal QRS configuration). The extrastimulus method showed, at first, that the A-V conduction time of the premature beat varied only slightly with the decrease of the coupling interval. From a critical A1A2 interval there was a sudden lengthening of A2H2 preceding the occurrence of re-entrant beats. The curve of H1H2 responses reflected these changes, showing two distinct parts. The second part following the slowing of the impulse included the initiation zone of atrial echoes and of reciprocating tachycardia. These results suggest the existence of two A-V pathways, one fast and the other slow. The point at which the break between the two parts of the curve occurred might be related to the effective refractory period of the fast pathway. In the same way, when atrial pacing reached a critical rate, it induced an abrupt increase of AH in five cases. In the sixth patient, A-V conduction time remained unchanged up to 170 per minute. Ventriculoatrial conduction was always observed, the delay of which did not lengthen with the rate. In one case tachycardia could be induced by a premature ventricular beat without lengthening of the V-A time. It is concluded that in spite of a normal PR interval, the presence of dual A-V pathways may be implied in the genesis of reciprocal rhythm.

[Discussion on therapeutic attitude in Prinzmetal's angina. Apropos of 6 cases]

1. 46 cases of Prinzmetal's angina have been studied: there were 36 males and 10 females, with an average age of 54.6 years. 19 patients (group A) were treated medically, and 12 of these were followed up for more than 6 months (average follow-up period 45.1 months). 27 patients (group B) underwent a coronary by-pass procedure: 22 of these were followed up for more than 6 months after surgery (average postoperative follow-up period 21.6 months). 2. One patient from group A and two patients from group B died, one of them from postoperative renal failure. None of the three deaths could be attributed directly to the coronary artery disease. 2 patients from group A and 5 patients from group B had a myocardial infarction without fatal outcome. 5 of the 12 patients in group A and 16 of the 22 patients in group B were asymptomatic after more than 6 months of follow-up. 3. The treatment policy should take account: - of the prognosis of Prinzmetal's angina, which is on the whole better than that of an unstable angina pectoris of the common type; - of an assessment of the risks in each individual case; these are increased when there is a combination of risk factors for atherosclerosis, and/or severe arrhythmia with syncope, and/or persistant electrical changes in the territory of the anterior descending artery, and/or coronary artery lesions involving two or three major vessels. 4. Surgery is used if there is a failure of treatment with beta-blockers, which are used under cover of a pacemaker when there is a paroxysmal block. If medical treatment is successful, surgery is indicated in high-risk cases.

[Ventricular tachycardia due to premature supra-ventricular beats with a normal QRS complex. Analysis of a case]

Report of attacks of ventricular tachycardia in a 39 year-old man, free from heart disease. Cardiac pacing showed that the tachycardia could be induced by premature supraventricular beats normally propagated to the ventricles, and by atrial acceleration. The same part played by the cardiac rate on triggering of attacks was demonstrated during ventricular pacing. Besides, the possibility to interrupt the tachycardia by one electrically induced ventricular beat, supports the hypothesis of a re-entry machanism. The QRS configuration during the arrythmia suggested a propagation of excitation starting from the posterior-inferior area of the left ventricle. However, the absence of anomalies of the supraventricular beats initiating the tachycardia excluded a circus movement resulting from a unidirectional block on the left anterior hemibranch. More probably there existed an area of micro-reentry, stimulating the left ventricle from the posterior branches of the His-Purkinje system.

[Electrophysiological study of 2 cases of ventricular pre-excitation compatible with the presence of Mahaim's fibers]

Report of two cases of ventricular pre-excitation in which the presence of Mahaim's fibres was suggested by the electro-physiological studies. In both cases, the short-circuit of the His bundle was responsible for the abnormally short HV interval. In a patient, atrial acceleration induced an increase of rh at first, related to an A-V delay without HV variation. For a cycle of 360 ms, HV lengthened suddenly from 15 to 40 ms while QRS changed configuration, which is in favour of a functional exclusion of an accessory pathway. Combination with the pre-excitation of a left bundle-branch block complicated, in this case, the problems of identification. The other case responded also to cardiac pacing by an increase of the A-V delay due mainly to intra-nodal conduction slowing. In the same time HV increases from 20 to 30 ms (for a cycle change from 480 to 315 ms) and the delta wave decreased progressively. For a higher rate there was a 2:1 A-V block proximal to H. The extrastimulus method produced initially the same results. On the contrary, when the coupling-interval decreased to 290 ms, HV increased suddenly from 25 to 45 ms, with disappearance of the pre-excitation pattern. At a still shorter interval, HV shortened again (25 ms) in parallel with a marked lengthening of the A-V nodal conduction times, thus revealing a "gap" phenomenon of the accessory pathway.

[Recurrent ventricular tachycardia due to hydatic cyst of the heart. Recovery after surgical resection. Report of one case]

Report of the case-history of a 66 year-old woman in whom the diagnosis of ventricular aneurysm was reached in 1958 during a systematic X-ray examination, while the electrocardiogram suggested a lateral-wall infarction with no anginal pain. After fifteen years of a practically asymptomatic course there were practically uninterrupted attacks of ventricular tachycardia. Coronary angiography and left ventriculography excluded the hypothesis of an aneurysm and suggested the diagnosis to cystic tumour of the left ventricle. A voluminous hydatic cyst was removed surgically. Ventricular arrhythmia did not recur since.