Early outcomes of usage of cryoFORM® probe for cryomaze procedure in congenital heart surgery.

OBJECTIVES: This study aimed to evaluate the early outcomes of patients who underwent a concomitant therapeutic maze procedure for congenital heart surgery. MATERIALS AND METHODS: Between 2019 and 2020, eight patients underwent surgical cryoablation by using the same type of cryoablation probe. RESULTS: Three patients had atrial flutter, two had Wolf-Parkinson-White syndrome, two intra-atrial reentrant tachycardia, and one had atrial fibrillation. Four patients underwent electrophysiological study. Preoperatively, one patient was on 3, two were on 2, five were on 1 antiarrhythmic drug. Six patients underwent right atrial maze and two underwent bilateral atrial maze. Five out of six right atrial maze patients underwent right atrial reduction. Nine different lesion sets were used. Some of the lesions were combined and applied as one lesion. In Ebstein's anomaly patients, the lesion from coronary sinus to displaced tricuspid annulus was delicately performed. The single ventricle patient with heterotaxy had junctional rhythm at the time of discharge and was the only patient who experienced atrial extrasystoles 2 months after discharge. Seven of the eight patients were on sinus rhythm. No patient needed permanent pacemaker placement. CONCLUSION: Cryomaze procedure can be applied in congenital heart diseases with acceptable arrhythmia-free rates by selecting the appropriate materials and suitable lesion sets. The application of cryomaze in heterotaxy patients can be challenging due to differences in the conduction system and complex anatomy. Consensus with the electrophysiology team about the choice of the right-left or biatrial maze procedure is mandatory for operational success.

Comparison of trace element levels after cardiopulmonary bypass between cyanotic and acyanotic patients.

Trace elements are essential micronutrients for the human body. In this study, we evaluated the alterations in copper, chromium, manganese, selenium, magnesium, zinc, iron, arsenic, boron, and silicon levels in children with cyanotic and acyanotic CHD who underwent cardiac surgery with cardiopulmonary bypass. Participants were divided into the following three groups: patients acyanotic CHDs (n=34), patients with cyanotic CHDs (n=30), and healthy controls (n=30). Blood samples were collected before the surgery and 1 hour after the sternum was closed. Serum trace elements were determined by Inductively Coupled Plasma Optical Emission Spectrometer-ICAP 6000. The baseline serum arsenic, manganese, and zinc levels of both patient groups were lower compared with controls, but there was no significant difference between baseline serum trace element levels of cyanotic and acyanotic patients. In both the patient groups, there was a significant decrease in postoperative serum arsenic, boron, copper, and zinc levels, and a significant increase in postoperative serum iron and magnesium levels. Silicon levels increased in cyanotic patients. Alterations in trace element levels were in the same direction in cyanotic and acyanotic patients. Copper, zinc, and manganase replacement may be needed after on-pump cardiac surgery.

Alterations in antioxidant and oxidant status of children after on-pump surgery for cyanotic and acyanotic congenital heart diseases.

OBJECTIVE: Oxidative stress refers to an imbalance between reactive oxidative species and antioxidants. In this case-controlled, prospective, observational study, we investigated the total oxidant status, total antioxidant status, oxidative stress index, and albumin and C-reactive protein levels of children with cyanotic and acyanotic congenital heart diseases who had undergone on-pump cardiac surgery. METHOD: The study groups consisted of 60 patients with congenital heart disease, who were operated under cardiopulmonary bypass, and a control group of 30 healthy individuals. The patients were classified into two groups. Among them, one was a patient group that consisted of 30 patients with acyanotic congenital heart disease and the other group consisted of 30 patients with cyanotic congenital heart disease. In the patient groups, blood samples were collected before surgery and at one and 24 hours following surgery. In control groups, blood samples were collected once during hospital admission. RESULTS: No statistically significant differences were found between the groups in terms of baseline total oxidant status, total antioxidant status, and oxidative stress index values. Regarding the postoperative first-hour and 24-hour total oxidant status and total antioxidant status levels as well as oxidative stress index values, there were no significant differences between the groups, except for an increase in total antioxidant status levels (p=0.002) 24 hours after surgery in cyanotic patients. CONCLUSION: There was no difference between oxidative stress status of cyanotic and acyanotic congenital heart disease patients and healthy individuals. Oxidative stress status of cyanotic and acyanotic patients does not change after cardiac surgery under cardiopulmonary bypass.

A comparison of three tumescent delivery systems in endovenous laser ablation of the great saphenous vein.

Different systems for delivering tumescent solution exist in endovenous laser ablation (EVLA). This study evaluated three different tumescent delivery systems in patients with primary varicose veins due to great saphenous vein reflux who were treated with EVLA. In this prospective non-randomized study, 60 patients with isolated GSV varicose veins were divided into three groups. All patients received EVLA treatment. Three different tumescent solution delivery systems were used. Systems consisted of a needle and a syringe in Group 1, a needle connected to an infusion bag system in Group 2 and a peristaltic infiltration pump in Group 3. Tumescent delivery durations were in Group 1: 6.56 SD 1.18 minutes, Group 2: 6.05 SD 2.19 minutes and Group 3: 5.19 SD 1.15 minutes (P = 0.014). In the outcomes of the study there were no significant difference between groups. Although peristaltic pump systems might provide shorter tumescent delivery durations without hand fatigue, shorter duration does not have any practical importance (about 1 minute and also it is not cost-effective. For delivering tumescent solutions in EVLA procedures, there was no major superiority between systems.

Repair of a stenotic bicuspid aortic valve by extensive leaflet shaving and commissuroplasty.

The surgical repair of the bicuspid aortic valve in children has been shown to have good outcomes. The repair can be done by the delicate use of native valve tissue without using patch material. The patient is an 8-year-old boy diagnosed with a stenotic bicuspid aortic valve and supravalvular aortic stenosis. He had a balloon valvuloplasty when he was 6 years old. This video tutorial gives detailed information on how to repair the aortic valve by reshaping the aortic cusps and reconstructing the aortic commissures.

Human transporters associated with antigen processing (TAPs) select epitope precursor peptides for processing in the endoplasmic reticulum and presentation to T cells.

Antigen presentation by major histocompatibility complex (MHC) class I molecules requires peptide supply by the transporters associated with antigen processing (TAPs), which select substrates in a species- and, in the rat, allele-specific manner. Conflicts between TAPs and MHC preferences for COOH-terminal peptide residues in rodent cells strongly reduce the efficiency of MHC class I antigen presentation. Although human TAP is relatively permissive, some peptide ligands for human histocompatibility leukocyte antigen class I molecules are known to possess very low TAP affinities; the significance of these in vitro findings for cellular antigen presentation is not known. We studied two naturally immunodominant viral epitopes presented by HLA-A2 that display very low affinities for human TAP. Low TAP affinities preclude minimal epitope access to the endoplasmic reticulum (ER) and assembly with HLA-A2 in vitro, as well as presentation by minigene-expressing cells to cytotoxic T lymphocytes. However, NH(2)-terminally but not COOH-terminally extended epitope variants with higher TAP affinities assemble in vitro and are presented to cytotoxic T lymphocytes with high efficiency. Thus, human TAP can influence epitope selection and restrict access to the ER to epitope precursors. Analysis of TAP affinities of a panel of viral epitopes suggests that TAP selection of precursors may be a common phenomenon for HLA-A2-presented epitopes. We also analyzed HLA-A2-eluted peptides from minigene-expressing cells and show that an NH(2)-terminally extended variant with low A2 binding affinity undergoes ER processing, whereas another with high affinity is presented unmodified. Therefore, the previously reported aminopeptidase activity in the ER can also act on TAP-translocated peptides.

Pentraxin 3 in primary percutaneous coronary intervention for ST elevation myocardial infarction is associated with early irreversible myocardial damage : Kinetic profile, relationship to interleukin 6 and infarct size.

BACKGROUND: The inflammatory marker long pentraxin 3 (PTX3) has been shown to be a strong predictor of 30-day and one-year mortality after acute myocardial infarction. The aim of this study was to evaluate the kinetic profile of PTX3 and its relationship with interleukin 6 (IL-6), high-sensitive C-reactive protein (hs-CRP) and infarct size. METHODS: PTX3, IL-6 and hs-CRP were measured at predefined time points, at baseline (before percutaneous coronary intervention (PCI)), at 12 and 72 hours after PCI in 161 patients with first-time ST elevation myocardial infarction (STEMI). RESULTS: PTX3 and IL-6 levels increased in the early phase, followed by a gradual decrease between 12 and 72 hours. There were statistically significant correlations between PTX3 and IL-6 in general, for all time points and for changes over time (0-72 hours). In a linear mixed model, PTX3 predicted IL-6 (p < 0.001). PTX3 is also correlated with hs-CRP in general, and at each time point post PCI, except at baseline. PTX3, IL-6 and hs-CRP were all significantly correlated with infarct size in general, and at the peak time point for maximum troponin I. In addition, there was a modest correlation between IL-6 levels at baseline and infarct size at 72 hours after PCI (ρ = 0.23, p = 0.006). CONCLUSIONS: PTX3 had a similar kinetic profile to IL-6, with an early increase and decline, and was statistically significantly correlated with markers of infarct size in STEMI patients post primary PCI. Baseline levels of IL-6 only predicted infarct size at 72 hours post PCI.

Early Infant Symptomatic Patients With Tetralogy of Fallot With Absent Pulmonary Valve: Pulmonary Artery Management and Airway Stabilization.

BACKGROUND: Tracheobronchomalacia and airway obstruction from severely dilated pulmonary arteries in tetralogy of Fallot with absent pulmonary valve (TOF-APV) has been associated with high rates of respiratory failure and mortality (15% to 25%). It is not known whether aggressive pulmonary artery (PA) or direct airway intervention during early definitive cardiac repair improves outcomes. METHODS: A retrospective observational study was made of all patients undergoing surgical repair for TOF-APV at our center between 2006 and 2018. RESULTS: Twenty patients underwent repair at a median age of 51 days and PA Z-scores of 8.1. Twelve patients had a valve implanted, 6 of whom required reoperation for valve replacement at a median of 9 months (range, 3 to 28) compared with 8 who had initial transannular patch, and only 1 patient required subsequent valve replacement (P < .05). Seven patients had central PAs replaced with thin-walled Gore-Tex (WL Gore, Flagstaff, AZ) grafts; none of these required PA reoperation during a median follow-up of 26.5 months, whereas 3 of 13 patients who did not have PA replacement with Gore-Tex required subsequent PA reoperation (P < .05). Concomitant airway interventions (eg, tracheobronchopexy/plasty) were performed in 4 patients and none required subsequent airway interventions, whereas 2 patients not having initial airway intervention required subsequent tracheopexy (P < .05). Three patients in the cohort eventually required tracheostomy (15%), and 2 patients died (10%; on postoperative days 30 and 326); none had received initial airway intervention. CONCLUSIONS: Pulmonary artery replacement and aggressive direct airway management at initial definitive repair of cardiac TOF-APV can be performed safely with acceptable survival outcomes and low rates of airway and PA reintervention.

Haemostatic actions of the folkloric medicinal plant extract Ankaferd Blood Stopper.

Ankaferd Blood Stopper (ABS), a standardized mixture of five plants, has been used historically as a haemostatic agent but its mechanism of action remains unknown. This study investigated the in vitro effects of ABS on haemostatic parameters. When added to plasma or serum, ABS induced the very rapid formation of a protein network and erythrocyte aggregation. The levels of coagulation factors II, V, VII, VIII, IX, X, XI, and XIII were not affected by ABS. Plasma fibrinogen activity and antigen levels were decreased following the addition of ABS, in parallel with the prolonged thrombin time. Total protein, albumin, and globulin levels decreased after the addition of ABS. Our findings suggest that ABS stimulates the formation of an encapsulated protein network that provides focal points for erythrocyte aggregation. ABS has the therapeutic potential to be used for the management of haemorrhage and this agent should be investigated further in clinical trials.

Cytotoxic T cell response against the chimeric p210 BCR-ABL protein in patients with chronic myelogenous leukemia.

Human chronic myelogenous leukemia (CML) is characterized by a translocation between chromosomes 9 and 22 that results in a BCR-ABL fusion gene coding for chimeric proteins. The junctional region of the BCR-ABLb3a2 molecule represents a potential leukemia-specific antigen which could be recognized by cytotoxic T lymphocytes (CTL). In fact, we identified a junctional nonapeptide (SSKALQRPV) which binds to HLA-A2.1 molecules. This peptide, as well as those binding to HLA-A3, -A11, and -B8 molecules (previously identified by others), elicits primary CTL responses in vitro from PBLs of both healthy donors and CML patients. Such CTL recognize HLA-matched, BCR-ABL-positive leukemic cells, implying efficient natural processing and presentation of these junctional peptides. Specific CTL were found at high frequency in 5 of 21 CML patients, suggesting that these epitopes are, to some extent, immunogenic in vivo during the course of the disease. These peptides could be useful for the development of specific immunotherapy in CML patients.

Impact of Coronary Artery Anatomy in Arterial Switch Procedure on Early Mortality and Morbidity.

OBJECTIVE: Arterial switch operation has become the treatment of choice for neonates with transposition of the great arteries. The most important step of the procedure is transferring the coronary arteries to the neoaorta successfully. This study shows the impact of coronary anatomy on early mortality and morbidity after arterial switch operation. METHODS: Ninety-two patients with transposition of the great arteries who underwent arterial switch operation between October 2010 and September 2014 were included in this retrospective study. The patients were classified into two groups: group I (n = 68, patients with usual coronary artery anatomy) and group II (n = 24, patients with unusual coronary artery anatomy). Median age was 10 days (6-25 days) in group I and 14 days (7-29 days) in group II. In group I, 25 patients had ventricular septal defect, nine patients had coarctation of the aorta or distal aortic arch hypoplasia, seven patients had Taussig Bing anomaly. In group II, nine patients had ventricular septal defect, one patient had coarctation of aorta, and one patient had Taussig Bing anomaly. RESULTS: Regarding the postoperative variables, no significant statistical difference was found between two groups. But cardiopulmonary bypass time is significantly longer in group II (P = .004). There was no difference in complications including the mortality (P = .265). It is statistically found that associated anomalies did not affect the mortality and complication rates. All mortality cases (n = 4) were related to ventricular dysfunction in group II, whereas only four of the eight patients died because of ventricular dysfunction in group I. CONCLUSION: Coronary artery pattern was not a predictor of mortality in early postoperative period. There may be an impact of unusual coronary artery pattern on the development of ventricular dysfunction as a cause of mortality.

Neutrophil-to-lymphocyte ratio in obstructive sleep apnea; a multi center, retrospective study.

OBJECTIVE: Systemic inflammation is important in pathophysiology of obstructive sleep apnea (OSA) and its comorbidity. Neutrophil to lymphocyte ratio (N/L ratio) is a novel inflammation index that has been shown to independently predict poor clinical outcomes. In this study, we aimed to evaluate the role of N/L ratio in OSA patients and comparing with other well-known inflammatory marker, C-reactive protein (CRP). PATIENTS AND METHODS: We conducted a retrospective analysis of 481 patients with mild, moderate and severe OSA (163,158 and 160 patients, respectively) and leukocyte profiles of 80 sex-, age- and body mass index- matched healthy controls. Patients were excluded if they had underlying cancer, chronic inflammatory disease, any systemic infection, uncontrolled hypertension and diabetes mellitus, a known acute coronary syndrome, valvular heart disease, a known thyroid, renal or hepatic dysfunction. RESULTS: We found that N/L Ratio in severe OSA patients was significantly higher compared with mild, moderate, OSA patients and healthy controls (p < 0.001). However, there was no difference between mild and moderate OSA patients (p = 0.636). There was also no significant difference between mild-moderate OSA patients and healthy groups (p = 0.150). CRP levels were not different in all OSA stages (p = 0.595). By Spearman correlation, there was no correlation between CRP and N/L ratio. CONCLUSIONS: N/L ratio, which is quick, cheap, easily measurable novel inflammatory marker with routine complete blood count analysis, is a surrogate marker of obstructive sleep apnea severity.

Left coronary artery stenosis causing left ventricular dysfunction in two children with supravalvular aortic stenosis.

Congenital supravalvar aortic stenosis (SVAS) is an arteriopathy associated with Williams-Beuren syndrome (WBS) and other isolated elastin gene deletions. Cardiovascular manifestations associated with WBS are characterized by obstructive arterial lesions such as SVAS and pulmonary artery stenosis in addition to bicuspid aortic valve and mitral valve prolapse. However, coronary artery ostial stenosis may be associated with SVAS, and it increases the risk of sudden death and may complicate surgical management. In this report, we present our experience with two patients having SVAS and left coronary artery ostial stenosis with associated left ventricular dysfunction.

Complete atrioventricular septal defect and pulmonary stenosis diagnosed in a 49-year-old woman after 10 uneventful births.

Atrioventricular septal defects constitute 4% of all congenital cardiac malformations. Patients with complete atrioventricular septal defect rarely survive for decades without surgical treatment. Pulmonary stenosis can provide a delicate balance between the pulmonary and systemic circulations and thereby increase longevity. We present the case of a 49-year-old woman whose complete atrioventricular septal defect and associated pulmonary stenosis were diagnosed only after she had given birth to 10 live children through uneventful spontaneous delivery. We discuss her successful surgical treatment in terms of the available medical literature.

Endovenous laser ablation for saphenous vein insufficiency: short- and mid-term results of 230 procedures.

OBJECTIVE: The present study aimed to evaluate the efficacy of endovenous laser ablation with a 1470-nm laser and to analyze the short- to mid-term results of endovenous laser ablation procedures to treat great saphenous vein insufficiency. METHOD: In this retrospective study, 200 patients (230 limbs) with symptomatic varicose veins secondary to great saphenous vein insufficiency treated with 1470-nm endovenous laser ablation were studied. Patients were evaluated clinically on the first day, first week, first month, and sixth month after the operation. Treated limbs were evaluated as separate treatment events. RESULTS: The short-term occlusion rate was 99% and mid-term occlusion rate was 100%. Induration or swelling was the most common minor complication (13%). No major complication such as deep venous thrombosis and pulmonary embolus occurred. Preoperatively documented mean venous clinical severity score significantly reduced from 4.9±2.3 to 2.5±1.1 (p<0.05). CONCLUSION: Endovenous laser ablation procedure of great saphenous vein with a 1470-nm diode laser is a minimally invasive, safe, and efficient treatment option in all-suitable patients with high short- and mid-term success rate.

Flt 3 ligand, MGDF, Epo and G-CSF enhance ex vivo expansion of hematopoietic cell compartments in the presence of SCF, IL-3 and IL-6.

The aim of the study is to define the ability of Flt3 ligand, MGDF, Epo and G-CSF to modulate the expansion of different hematopoietic compartments in association with a basic cocktail of SCF + IL-3 + IL-6 (S36). CD34+ cells from normal bone marrow were cultured in stroma-free, serum-free medium for 10 days. Using various concentrations of cytokines, total cells could be expanded up to 5200-fold, CD34+ cells up to 78-fold, CFU-GM up to 143-fold, BFU-E up to 46-fold, CFU-MK up to six-fold and LTC-IC up to four-fold. The results were assessed by multiparametric analysis of variance. Three factors had a significant stimulatory effect on the late precursor compartment: Epo (P < 10(-5)), G-CSF (P=5 x 10(-3)) and FL (P=10(-5)). Two were critical for CD34+ cell expansion: FL (P=4 x 10(-5)) and Epo (P=6 x 10(-5)), while two were critical for BFU-E expansion: MGDF (P=8 x 10(-4)) and FL (P=0.017). FL strongly stimulated CFU-GM expansion (P < 10(-5)), whereas none of the growth factors studied had any effect on CFU-MK. FL (P=10(-4)) and MGDF (P=0.002) were essential to obtain high levels of expansion of LTC-IC as determined in limiting dilution assays. In the light of the above results showing a preferential effect on the expansion of precursor cells (3080-fold), CD34+ cells (53-fold), CFU-GM (134-fold), BFU-E (46-fold) and LTC-IC (five-fold), the combination SCF, IL-3, IL-6, FL, MGDF, Epo and G-CSF was chosen as a putative cytokine cocktail for further studies on long-term culture. Sustained production of precursor cells, progenitor cells, LTC-IC and E-LTC-IC for up to 100 days reflects the persistence of very primitive stem cells. This suggests that these populations are probably able to undergo self-renewal divisions. The above combination of cytokines meets the required criterion for potential clinical application, which may be defined as an effective capacity to expand all cell compartments, using as the starting material high concentrations of low purity CD34+ cells.

Ex vivo expansion of CD34-positive peripheral blood progenitor cells from patients with non-Hodgkin's lymphoma: no evidence of concomitant expansion of contaminating bcl2/JH-positive lymphoma cells.

The aim of the present study was to evaluate the capacity to expand of hematopoietic stem cell (HSC) samples from eight patients with NHL, and to follow in parallel the fate of tumor cells in four of eight samples still containing bcl2/JH+ tumor cells after CD34+ or CD19-/20-/34+ cell selection. The presence of bcl2/JH+ cells was also investigated after expansion in four of eight samples, two of which were bcl2/JH at harvesting and two which were initially bcl2/JH+ but became bcl2/JH (below the level of PCR detection) after cell selection, to assess a possible reappearance of occult tumor cells after expansion culture. We used culture conditions that we previously had established to allow high level expansion of normal precursors, progenitors and LTC-ICs. In this study, particular attention was given to the role of Flt3-ligand, known to favor the growth of B cells. The expansion conditions were: 1.5 x 10(3) cells/ml in serum-free medium containing stem cell factor (SCF), interleukin-3 (IL-3), IL-6, granulocyte-stimulating factor (G-CSF), erythropoietin (Epo) +/- Flt3-ligand (Flt3-L) for 10 days. After culture, total cells, CFU-GMs, BFU-Es and LTC-ICs were expanded to a mean of 833-, 6.6-, 4.6-, and 1.8-fold, respectively with the cocktail of cytokines not including Flt3-L. When Flt3-L was added, the mean expansion values were 1095-, 31-, 15- and three-fold, respectively. Residual bcl2/JH+ cells present in four of eight samples before expansion were not detected after expansion. Similarly, no tumor cells reappeared after expansion of the two samples which had become negative after selection, as well as in the two samples which were bcl2/JH- at harvesting. These results suggest first that ex vivo expansion of hematopoietic stem cells in patients with non-Hodgkin's lymphoma is feasible without incurring the parallel risk of amplifying tumor cells; second, that Flt3-L did not stimulate the growth of tumor cells while it clearly favored the growth of normal progenitors.

Cell culture bags allow a large extent of ex vivo expansion of LTC-IC and functional mature cells which can subsequently be frozen: interest for a large-scale clinical applications.

The aim of this study was to evaluate the ex vivo expansion of normal CD34+ cells in gas-permeable polypropylene bags suitable for clinical use. Cells were cultured for 14 days in serum-free medium supplemented with SCF, IL3, IL6, FLT3-1, G-CSF + MGDF or Epo. The bags supported the expansion of hematopoietic cells in a similar manner to small scale well or flask systems, allowing mean expansions of up to 2193-fold for total nucleated cells, 140-fold for CFU-GM and 66-fold for LTC-IC. Increasing the initial cell concentration from 5 x 10(3) to 1 x 10(5)CD34+ cells/ml induced the production of granulocytic cells with terminal differentiation while simultaneously decreasing the overall extent of expansion of the white blood cells produced. We tested the phagocytic activity and oxidative metabolism of the white blood cells produced. The percentage of phagocytic cells was 39+/-0.5% in expanded cultures derived from fractions initiated at 5 x 10(3), 10(4) or 10(5) cells/ml and 45+/-6% in cultured cells obtained from starting fractions containing 5 x 10(4) cells/ml, as compared to 58+/-4% in normal controls. A study of the potential for oxygen-dependent microbe killing showed that the expanded cells produced H2O2, although in lesser quantities than control cells. We subsequently investigated the possibility of freezing expanded cells. Total cell recovery after thawing was 45+/-4%, while recoveries of progenitors and stem cells ranged from 65 to 90%, without any influence of the initial cell concentration. This new approach could be of major interest for clinical practice, as it would allow evaluation of the quality of a graft prior to its infusion and employs experimental conditions which meet the criteria for potential clinical use.

Comparison of CD34+ bone marrow cells purified by immunomagnetic and immunoadsorption cell separation techniques.

We tested two positive selection techniques for separation of CD34+ cells from bone marrow and analyzed the yields of CD34+ cells, BFU-E, CFU-GM, CFU-MK and LTC-IC after selection and expansion. An immunoadsorption procedure (CellPro) and an immunomagnetic (Baxter) CD34+ cell separation method were employed to purify the same bone marrow samples from seven normal subjects. Mean yields of CFU-GM and CFU-MK and absolute numbers of LTC-ICs were not different in the two purified cell populations. In contrast, the mean recovery of BFU-E was significantly lower for the immunoadsorption (21 +/- 14%) than for the immunomagnetic technique (44 +/- 27%). After separation, CD34+ cells were evaluated in 10-day liquid cultures for their expansion capacity in terms of total cells and progenitors. The expansion capacity of progenitors such as CFU-GM, CFU-MK and especially BFU-E selected by immunoadsorption was higher than the capacity of progenitors obtained by immunomagnetism, although final total and progenitor cell numbers are similar. Our results suggest that the populations separated by the two techniques differ mainly in the expansion capacity of progenitors and in the recovery of BFU-E after the selection procedure. These differences between two methods, which already are widely employed in research and in clinical transplantation, should be taken into account when considering the aims of the experiments.

Determination of myeloid antigen expression on childhood acute lymphoblastic leukaemia cells: discrepancies using different monoclonal antibody clones.

Prospective clinical studies including large numbers of patients have led to the conclusion that co-expression of myeloid antigens in childhood acute lymphoblastic leukaemia (My+ ALL) does not have prognostic significance. However, reports of the frequency of My+ ALL in children vary widely across laboratories using different mAb clones and staining and analysing procedures. Taking two commonly accepted thresholds of positivity for myeloid antigens (20 and 30%), we analysed the immunoreactivity of the most widely employed mAb clones against CD13 (SJ1D1, L138 and My7) and CD33 (My9, P67.6 and D3HL60) and compared the proportions of My+ ALL detected by these clones in childhood ALL. The correlation between myeloid antigen expression and the presence of the t(12;21) translocation was analysed concomitantly in the same samples. The percentage of ALL cases positive for myeloid markers varied significantly depending on the mAb clone and the positive threshold. Among patients with B-ALL, the proportion of CD13+ ALL was significantly lower using SJ1D1 than using L138 or My7, while the proportion of CD33+ ALL was significantly higher for My9 than for P67.6 or D3HL60. Analysis of the co-expression of CD13 and CD33 on B-ALL cells using combinations of mAb clones showed that this frequency was either underestimated by the SJ1D1/D3HL60 or overestimated by the L138/P67.6 and My7/My9 combinations. A correlation between CD13/CD33 positivity and the t(12;21) translocation was uniformly observed in B-ALL patients for a positive threshold of 30%, whereas SJ1D1/D3HL60 detected no correlation between t(12;21) and CD13/CD33 positivity when the threshold was lowered to 20%. These data show that the mAb clones commonly used to detect the CD13 and CD33 surface antigens have variable immunoreactivity against childhood ALL cells, which may partly explain the conflicting reports concerning the prognostic significance of myeloid antigen expression in paediatric ALL and its association with different translocations. The present findings may also be of clinical importance for therapeutic choices.