Improved specificity of determination of immature erythrocytes (reticulocytes) by multiparameter flow-cytometry and thiazole orange using combined staining with monoclonal antibody (anti-glycophorin-A)

Applying thiazole orange stain and multiparameter flow-cytometry, immature erythrocytes, e.g., reticulocytes, can be discriminated from the mature erythrocytes by virtue of their higher RNA-content. One major problem of this method, however, consists in the inclusion of nucleated cells (leucocytes) and large RNA-containing platelets in the population defined by light scatter-patterns as erythrocytes. Due to the high intensity of staining with thiazole orange of all these cellular elements, all of them in the analysis are prone to be classified erroneously as reticulocytes. In order to classify elements in analysis properly as erythroid (reticulocytes+mature erythrocytes) or as non-erythroid (leucocytes+platelets), an alternative staining method is shown in this paper, consisting of thiazole orange combined to anti-glycophorin-A-PE-monoclonal antibody.

Immune parameters in patients with anxiety or depression during psychotherapy

BACKGROUND

Numerous studies have described distinctive immunological findings in patients with depression. In contrast, only very little is known about the possible influence of anxiety disorders on the immune system. It is also unknown whether treatment with psychotherapy alone has any influence on immunological variations in patients with psychiatric disorders.

METHODS

We measured immunological and psychological parameters in patients with minor depression (N=10) or anxiety disorder (N=13) over an 8-week course of inpatient psychotherapy. Data for patients and a group of healthy controls (N=11) were recorded three times in 4-week intervals. A FACS analysis revealed the composition of lymphocyte subpopulations. The production of reactive oxygen species (ROS) by phagocytes was analyzed using lucigenin-enhanced chemiluminescence.

RESULTS

On admission, patients with anxiety disorder showed a markedly elevated ratio of CD4(+) (T helper) versus CD8(+) (T suppressor/cytotoxic) lymphocytes compared to healthy controls (P<0.001) and minor depressives (P<0.01). The increased ratio in patients with anxiety disorder could mainly be attributed to a reduced count in CD8(+) T cells compared to healthy controls (P<0.01) and depressives (P<0.05). There were no differences between patients with depression and healthy controls with respect to the CD4(+)/CD8(+) ratio. We did not observe any differences in the production of ROS by phagocytes in patients compared to healthy controls. The CD4(+)/CD8(+) ratio remained elevated in patients with anxiety disorders during the following 8 weeks. There were no significant changes in this parameter over the course of the inpatient treatment.

LIMITATIONS

As a pilot study on the immune status in patients with anxiety disorders, the study's main limitation is the relatively low number of patients observed.

CONCLUSIONS

In this study we demonstrated for the first time marked immunological changes in patients with anxiety disorders. In addition, our results provide preliminary evidence that these immunological variations are not reversible by an 8-week course of inpatient psychotherapy alone.

Acute psychological stress simultaneously alters hormone levels, recruitment of lymphocyte subsets, and production of reactive oxygen species

Very little is known about the effects of acute psychological stress on the production of reactive oxygen species (ROS) by human phagocytic cells and the interplay between subjectively perceived stress, mediating hormones, variations in the number of peripheral leukocytes and ROS production. We measured psychological reactions, cardiovascular parameters, plasma catecholamines, plasma prolactin and cortisol as well as peripheral lymphocyte subsets in 13 experimental subjects undergoing a brief psychological stressor, and production of ROS, as indicated by chemiluminescence (CL), in stressed subjects and in healthy controls. The stressor elevated anger (p<0.01) and cardiovascular activation (p<0.01). There were significant changes in plasma levels of cortisol (p<0.01) and prolactin (p<0.001). During psychological stress natural killer (NK) cells (p<0.01) and CD8/CD38 cells (p<0.05) increased and returned to baseline only 25 minutes later. Significant changes in the number of naive CD4+/CD45RA+ (p<0.01) and antigen-experienced CD8+/CD45RO+ T cells (p<0.05) occurred. Subjects with stronger cardiovascular reaction showed higher stress-related plasma levels of norepinephrine (p<0.05) and were mainly responsible for the increase in NK cells. We observed a significantly reduced production of ROS following the stress test (p<0.05). Our results show that psychological stress is expressed simultaneously on psychological, hormonal and immunological levels of the organism. We show the existence of a circadian rhythm leading to a pronounced increase in CL during the morning hours. This first study taking this circadian rhythm in account revealed a significant suppressive effect of stress on ROS production.

Rituximab therapy of patients with B-cell chronic lymphocytic leukemia

Rituximab (IDEC-C2B8) is a chimeric antibody that binds to the B-cell surface antigen CD20. Rituximab has significant activity in follicular non-Hodgkin lymphomas. Much less is known about the effects in chronic lymphocytic leukemia (CLL). We have initiated a phase II trial to evaluate the efficacy and safety of rituximab in patients with CD20+ pretreated CLL. To avoid the rituximab-associated toxicity, we restricted the tumor cell load, as measured by the number of circulating lymphocytes and the spleen size, in the first 2 cohorts of patients included in the study. Patients received 4 intravenous infusions of 375 mg/m2 once a week over a period of 1 month. Of the 28 patients evaluable for response, 7 patients showed a partial remission (National Cancer Institute criteria) lasting for a median of 20 weeks, with 1 patient still in remission after 71 weeks. Based on lymphocyte counts only, we found at least a 50% reduction of lymphocyte counts lasting for at least 4 weeks in 13 (45%) of 29 patients. Fifteen patients from 3 institutions were monitored for the immunophenotype profile of lymphocyte subsets. The number of CD5+CD20+ cells decreased significantly and remained low until day 28 after therapy. T-cell counts were not affected. With the exception of one rituximab-related death, adverse events in the remaining patients were mild. The results suggest that rituximab has clinical activity in pretreated patients with B-CLL. Toxicity is tolerable. Response duration after withdrawal of rituximab is rather short. Therefore, other modes of application and the combination with other agents need to be tested.

Inverse relationship between patient peripheral blood CD34+ cell counts and collection efficiency for CD34+ cells in two automated leukapheresis systems

BACKGROUND

The purpose of this study was to analyze the CD34 cell collection efficiency (CE) of automated leukapheresis protocols of two blood cell separators (Spectra, COBE [AutoPBSC protocol] and AS104, Fresenius [PBSC-Lym, protocol]) for peripheral blood progenitor cell (PBPC) harvest in patients with malignant diseases.

STUDY DESIGN AND METHODS

PBPCs were collected by the Spectra AutoPBSC protocol in 95 patients (123 collections) and the AS104 PBSC-Lym protocol in 87 patients (115 harvests). Patients underwent a median of one (range, 1-4) conventional-volume apheresis procedure of 10.8 L (9.0-13.9) to obtain a target cell dose of > or =2.5 x 10(6) CD34+ cells per kg.

RESULTS

The median overall CD34 CE was significantly better on the AS104 than on the Spectra: 55.8 percent versus 42.4 percent (p = 0.000). This was also true below (59.2% vs. 50.1%; p = 0.022) and above (51.2% vs. 41.3%; p = 0.001) the preleukapheresis threshold of 40 CD34+ cells per microL needed to collect a single-apheresis autograft. However, at > or =40 circulating CD34+ cells per microL, both cell separators achieved the target of > or =2.5 x 10(6) CD34+ cells per kg. The CD34 CE dropped significantly, from 59.2 percent at <40 cells per microL to 51.2 percent at > or =40 cells per microL on the AS104 (p = 0.017) and from 50.1 percent to 41.3 percent on the Spectra (p = 0.033).

CONCLUSION

Whereas the CD34 CE was significantly different with the AS104 and the Spectra, the CD34 CE of both machines correlated inversely with peripheral blood CD34+ cell counts, showing a significant decline with increasing numbers of circulating CD34+ cells. Nevertheless, at > or 40 preapheresis CD34+ cells per microL, sufficient hematopoietic autografts of > or =2.5 x 10(6) CD34+ cells per kg were harvested by a single conventional-volume (11 L) leukapheresis on both cell separators.

Monoclonal antibody FMC7 detects a conformational epitope on the CD20 molecule: evidence from phenotyping after rituxan therapy and transfectant cell analyses

Numerous studies have reported that monoclonal antibody (mAb) FMC7 detects an antigen present on only a subset of circulating B lymphocytes. In particular, this mAb may distinguish typical B-cell chronic lymphocytic leukemia (FMC7 negative) from other types of B-cell non-Hodgkin lymphoma (B-NHL; FMC7 positive). We treated patients with B-NHL with Rituxan, a chimeric CD20 mAb, and observed abrogation of staining not only with prototype CD20 mAb B-1 but also with mAb FMC7. To investigate the relation between antigens CD20 and FMC7, we performed mutual blocking studies that showed mutual inhibition of FMC7 and CD20. In addition, FMC7 modulated CD23 expression and confirmed the presence of mAb B-1 in B-lymphoblastoid cell lines CESS and JVM. Transient transfection of myeloid cell line K562 with plasmid containing CD20-encoding cDNA produced de novo expressions of CD20 and FMC7. Our data indicate that FMC7 binds to a particular conformation of the CD20 antigen, probably to a multimeric CD20 complex. We assume that FMC7 stains positively only when CD20 antigen is present in high densities and in the postulated multimeric complex formation.

A European reference protocol for quality assessment and clinical validation of autologous haematopoietic blood progenitor and stem cell grafts

Recently, the regulatory authorities have begun to show interest in haematopoietic stem cell products. On a professional rather than a regulatory basis, the International Society for Hematotherapy and Graft Engineering (ISHAGE) has established the Foundation for the Accreditation of Haematopoietic Cell Therapy (FACHT), which has drawn up guidelines for standards and accreditation of such activity. In Europe, the regulatory environment with regard to haematopoietic stem cell grafts, processing and storage are currently less stringent. However, in 1998 the European Joint Accreditation Committee Euro-ISHAGE/EBMT (JACIE) prepared a regulatory document 'Standards for Blood and Marrow Progenitor Cell Collection, Processing and Transplantation' which was approved by the EBMT General Assembly. The major objectives were to promote quality of medical and laboratory practice in haematopoietic progenitor cell transplantation. The standards extend and detail the pre-existing activity of EBMT centres including all phases of collection, processing and administration of these cells. This is the platform for the proposed reference protocol for CD34(+) cell enumeration and clinical validation of quality assessment to ensure that appropriate standards of work and product quality are established and will be maintained.

Automated collection of peripheral blood stem cells with the COBE spectra for autotransplantation

BACKGROUND

A convenient, effective and safe peripheral blood stem cell (PBSC) apheresis procedure is desirable to cope with the increasing requirements for PBSC collections. We performed PBSC harvesting with the novel COBE Spectra AutoPBSC(TM) system using the default software configuration recommended by the manufacturer. We analyzed collection parameters and clinical efficiency of harvested autografts following high-dose chemotherapy (HDCT).

PATIENTS AND METHODS

Eighty-one patients underwent 102 harvests after standard chemotherapy plus filgrastim (5-10 microg/kg/day) to obtain a target of >/=2.5 x 10(6) CD34+ cells/kg for autologous blood stem cell transplantation. Conventional-volume leukaphereses (median: 11 liters) were performed using the manufacturer's standard software default regarding inlet flow, harvest/chase volume (3/7 ml) and number of collection cycles. The ratio of ACD-A to whole blood was initially set at 1:12 (56 collections), later at 1:10 (46 aphereses).

RESULTS

With respect to preapheresis counts of 93 (9-876) CD34+ cells/microl, 69 patients (85.2%) achieved >/=2.5 x 10(6) CD34+ cells/kg by the first apheresis. PBSC products contained medians of 5.0 x 10(6) (0.7-77.3) CD34+ cells/kg and 13.8 x 10(4) (2.3-105.0) CFU-GM/kg. A preapheresis count of >/=40 CD34+ cells/microl predicted a single-apheresis yield of >/=2.5 x 10(6) CD34+ cells/kg. Apheresis products showed a high mononuclear cell (MNC) purity of >/=89%. The median overall collection efficiency of CD34+ cells (CD34-CE) was 42.6% (12.2-87.4). The CD34-CE decreased significantly with increasing numbers of circulating CD34+ cells: 52.5% at CD34+ cells <40/microl versus 41.0% at CD34+ cells >/=40/microl (p </= 0. 002). Coagulation problems occurred in 3 of 56 procedures at an ACD-A to whole blood ratio of 1:12, but in no case at 1:10. Patients who underwent HDCT and autologous blood stem cell transplantation (n = 40) engrafted in a median time of 9 (8-13) days for absolute neutrophil counts >0.5 x 10(3)/microl, 10 (8-13) days for WBC >1.0 x 10(3)/microl and 11 (8-17) days for platelets >20 x 10(3)/microl.

CONCLUSIONS

As a result of efficient PBSC mobilization, a single conventional-volume leukapheresis with the COBE Spectra AutoPBSC system resulted in hematopoietic autografts with >/=2.5 x 10(6) CD34+ cells/kg in 85% of patients. Following the standard PBSC apheresis recommendations of the manufacturer, the AutoPBSC system assures PBSC products with a high MNC purity and a moderate CD34-CE that declines significantly at increasing levels of circulating CD34+ cells. Leukaphereses performed at an ACD-A to whole blood ratio of 1:10 should run without coagulation problems.

PBPC mobilization with paclitaxel, ifosfamide, and G-CSF with or without amifostine: results of a prospective randomized trial

BACKGROUND

The impact of amifostine on PBPC mobilization with paclitaxel and ifosfamide plus G-CSF was assessed.

STUDY DESIGN AND METHODS

Forty patients with a median age of 34 years (range, 19-53) who had germ cell tumor were evaluated for high-dose chemotherapy. Patients were randomly assigned to receive either a single 500-mg dose of amifostine (Group A, n = 20) or no amifostine (Group B, n = 20) before mobilization chemotherapy with paclitaxel (175 mg/m(2)) given over 3 hours and ifosfamide (5 g/m(2)) given over 24 hours (TI) on Day 1. G-CSF at 10 microg per kg per day was given subsequent to TI with or without amifostine from Day 3 until the end of leukapheresis procedures.

RESULTS

In 2 (10%) of 20 patients receiving amifostine and 3 (15%) of 20 patients not receiving it, no PBPC separation was performed because of mobilization failure. No significant differences were observed in the study arms with regard to the time from chemotherapy until first PBPC collection or the number of apheresis procedures needed to harvest more than 2.5 x 10(6) CD34+ cells per kg. Furthermore, leukapheresis procedures yielded comparable doses of CD34+ cells per kg (3.4 x 10(6) vs. 3.6 x 10(6); p = 0.82), MNCs per kg (2.7 x 10(8) vs. 2.6 x 10(8); p = 0.18), and CFU-GM per kg (15.9 x 10(4) vs. 19.3 x 10(4); p = 0.20). Patients in Group A had higher numbers of circulating CD34+ cells on Day 10 (103.0/microL vs. 46.8/microL; p = 0.10) and on Day 11 (63.0/microL vs.14.3/microL; p = 0.04) than did patients in Group B.

CONCLUSION

Administration of a single dose of amifostine before chemotherapy with TI mobilized higher numbers of CD34 cells in the circulation, but did not enhance the overall collection efficiency in the present trial.

Circulating CD4+ T lymphocytes with intracellular but no surface CD3 antigen in five of seven patients consecutively diagnosed with angioimmunoblastic T-cell lymphoma

Angioimmunoblastic T-cell lymphoma (AITL) accounts for less than 1% of all lymphatic malignancies. Oligoclonality or monoclonality for any of the T-cell receptor (TCR) chain genes can be demonstrated in the majority of the cases. During systematic screening for the presence of circulating lymphocytes with atypical coexpression of differentiation antigens in patients with T-cell lymphomas, we have discovered a minor population (accounting for 0.2% to 10.% of all lymphocytes) of atypical lymphocytes in the blood of five of seven patients consecutively diagnosed in 1997/1998 by lymph node histology to have AITL. The major distinguishing feature of these cells consists of the lack of the surface expression of the CD3 antigen, but not of the intracellular expression. These cells express the T-cell antigens CD2 and CD5 on their surface, but not CD7, and they express CD4 and CD45 at numbers of molecules per cell typical for T lymphocytes. Gene scan analyses for the TCR gamma chain revealed oligoclonality of these flow-sorted cells in one patient and monoclonality in two patients, the same patterns of TCR gamma chain gene as determined processing the respective diagnostic lymph nodes. Circulating CD4-expressing T lymphocytes with exclusively cytoplasmic expression of CD3 appear to represent the malignant population in patients with histologically diagnosed AITL.

Immunomagnetic selection of CD34+ cells: factors influencing component purity and yield

BACKGROUND

In immunomagnetic selection of CD34+ cells from HPC transplants, not all factors that affect yield and purity of CD34+ cells are known.

METHODS

Forty-three consecutive procedures of immunomagnetic selection of CD34+ cells from peripheral blood HPCs and bone marrow harvests (autologous harvests, n = 27; allogeneic harvests; n=16) were performed by use of a cell selection system (Isolex 300i, Baxter Immunotherapy). The composition of the starting component and the subsets of CD34+ cells were analyzed for correlation with the yield and purity of the final component.

RESULTS

The mean purity of the final components was 84.3 percent (range, 27-99%), and the mean yield was 51.4 percent (range, 9.4-80. 4%). Partial regression analysis showed that, among the factors correlating with purity and/or yield, the RBC volume in the starting fraction had the highest predictive impact on the purity and yield of CD34+ cells, even after the exclusion of procedures using bone marrow harvests as an HPC source (beta coefficient, -0.704; p = 0. 001).

CONCLUSION

The use of the Isolex 300i system allows efficient recovery of CD34+ cells in routine selection procedures. The volume of RBCs in the starting component should be minimized to ensure a high yield and purity of the final component.

Important role of nondiagnostic blood loss and blunted erythropoietic response in the anemia of medical intensive care patients

OBJECTIVE

To determine incidence, severity, characteristics, and causes of anemia and transfusion requirements in medical intensive care patients.

DESIGN AND SETTING

Open prospective clinical study in a 24-bed medical intensive care unit in a tertiary-care university hospital.

PATIENTS

Patients (N = 96) treated in the intensive care unit for >3 days.

INTERVENTIONS

None.

MEASUREMENTS

Parameters of erythropoiesis and red blood cell metabolism, including hemoglobin, reticulocyte counts, serum iron, transferrin, ferritin, haptoglobin, vitamin B12, folic acid, and erythropoietin concentrations were determined serially. Diagnostic blood loss and red blood cell transfusions were recorded, and the total blood loss was estimated from changes in hemoglobin concentrations and the amount of hemoglobin transfused.

MAIN RESULTS

The median hemoglobin concentration was 12.1 g/dL at admission and 11.2 g/dL at the end of the intensive care unit stay. A total of 74 patients (77%) suffered from anemia and received 257 red blood cell units, approximately half of which were given within the first 5 days. Three patients who received 19 red blood cell units were admitted with acute gastrointestinal bleeding, but in the remainder, a median total blood loss of 128 mL/d was not (n = 60) or not solely (n = 11) a result of overt bleeding. Diagnostic blood loss declined from a median of 41 mL on day 1 to <20 mL after 3 wks and contributed 17% (median) to total blood loss. Acute renal failure, fatal outcome, and simplified acute physiology score >38 on admission were associated with a 5.8-, 7.0-, and 2.8-fold increase in total blood loss. Reticulocyte counts and erythropoietin concentrations were inappropriately low for the degree of anemia, and plasma transferrin saturation was mostly <20%.

CONCLUSIONS

Anemia is frequent and results in a high requirement for red blood cell transfusions in the medical intensive care setting. A major proportion of blood loss is not caused by overt bleeding or diagnostic blood sampling but, rather, may result from various other reasons, e.g., occult gastrointestinal bleeding and renal replacement therapy. The erythropoietic response to anemia is blunted, probably as a consequence of an inappropriate increase in erythropoietin production and diminished iron availability. (Crit Care Med 1999; 27:2630-2639)

Influenza vaccination in liver transplant recipients

BACKGROUND

The immunogenicity of the trivalent inactivated influenza split virus vaccine (Infusplit SSW 97/98) containing A/Bayern/07/95 (H1N1)-like (A/Johannesburg/82/96 [NIB-39]), A/Wuhan/359/95 (H3N2)-like (A/Nanchang/933/95 [Resvir-0]), and B/Beijing/184/93-like (B/Harbin/7/94) hemagglutinin antigens was tested in liver transplant recipients (TXL-R).

SUBJECTS AND METHODS

Serum antibody titers were determined 21+/-2 days after a single vaccination in 62 adult TXL-R and 59 adult volunteers.

RESULTS

Protective postimmunization antibody titers for the three antigens were similar in TXL-R (protection rates 92%, 92%, and 95%) and the comparison group (97%, 100%, and 100%). Adverse reactions were mild and less frequent in TXL-R. A significant decrease of CD8+CD38+ lymphocytes after vaccination was found in TXL-R. No association between antibody response and age, gender, time interval since transplantation, anti-hepatitis B surface antigen immunoprophylaxis, or immunosuppressive medication was detected.

CONCLUSION

Our results show that the vaccine is safe and effective and should be recommended to TXL-R.

Elevated reticulocyte count--a clue to the diagnosis of haemolytic-uraemic syndrome (HUS) associated with gemcitabine therapy for metastatic duodenal papillary carcinoma: a case report

In adults, the haemolytic-uraemic syndrome (HUS) is associated with probable causative factors in the minority of all cases. Cytotoxic drugs are one of these potential causative agents. Although metastatic cancer by itself is a recognized risk-factor for the development of HUS, therapy with mitomycin-C, with cis-platinum, and with bleomycin carries a significant, albeit extremely small, risk for the development of HUS, compared with all other cytotoxic drugs. Gemcitabine is a novel cytotoxic drug with promising activity against pancreatic adenocarcinoma. We are reporting on one patient with metastatic duodenal papillary carcinoma developing HUS while on weekly gemcitabine therapy. The presenting features in this patient were non-cardiac pulmonary oedema, renal failure, thrombocytopenia and haemolytic anaemia. The diagnosis of HUS was made on the day of admission of the patient to this institution. Upon aggressive therapy, including one single haemodialysis and five plasmaphereses, the patient recovered uneventfully, with modestly elevated creatinine-values as a remnant of the acute illness. Re-exposure to gemcitabine 6 months after the episode of HUS instituted for progressive carcinoma, thus far has not caused another episode of HUS.

Quantitative fluorescence flow cytometry: a comparison of the three techniques for direct and indirect immunofluorescence

Three types of microbead calibrators available for quantitative fluorescence flow cytometry have been studied in parallel using a variety of monoclonal antibodies (MoAbs). The QIFI kit is designed for indirect immunofluorescence (IF), and both the Quantum Simply Cellular (QSC) assay and the Quanti-BRITE assay are designed for direct IF. Because of the different nature of the respective ligands, epitopes on cells versus F'ab-portions on QSC beads, large differences in titration curves for a large number of CD MoAbs were noted between QSC beads and cells. Use of the QSC assay and fluorescein isothiocyanate (FITC) and phycoerythrin (PE) conjugates of the same CD reagent revealed substantially different numbers of cellular binding sites. Numbers of cellular binding sites as determined by direct IF using the Quanti-BRITE assay and by indirect IF using the QIFI kit were similar. We also found that erythrocyte (RBC)-lysing reagents cause varying and sometimes substantial reduction in the fluorescence intensity (FI) of cells stained directly with CD34 MoAb conjugates, but the RBC-lysing reagents had no effect on the FI of cells stained indirectly with the same CD34 MoAbs. This report defines a number of variables critical for standardized quantitative flow cytometry. We conclude that the choice of calibrators, fluorochrome conjugates, staining methods, and modes of sample processing can effect the determination of cellular binding sites to MoAbs. Direct immunofluorescence using the Quanti-BRITE assay and indirect IF using the QIFI kit appear to yield comparable results for the standardized determination of numbers of cellular binding sites to MoAbs.

Analysis of CD34-expressing cells in clinical practice

The flow cytometric determination of haemopoietic cells defined as CD34-expressing cells has greatly added to the improvement of the management of harvesting circulating haemopoietic cells for subsequent autologous reinfusion in the setting of high-dose chemo/(radio)-therapy. Additionally, this flow cytometric determination has replaced, in some institutions, the in-vitro culture test for CFU-GM as the measure to estimate the haemopoietic potential of the cells to be reinfused/transplanted.

Flow cytometric enumeration of CD34+ hematopoietic stem and progenitor cells. European Working Group on Clinical Cell Analysis

The need for a rapid and reliable marker for the engraftment potential of hematopoietic stem and progenitor cell (HPC) transplants has led to the development of flow cytometric assays to quantitate such cells on the basis of their expression of CD34. The variability associated with enumeration of low-frequency cells (i.e., as low as 0.1% or 5 cells/microl) is exceedingly large, but recent developments have improved the accuracy and precision of the assay. Here, we review and compare the major techniques. Based on the current state of the art, we recommend 1) bright fluorochrome conjugates of class II or III monoclonal antibodies (mAbs) that detect all glycoforms of CD34, 2) use of a vital nucleic acid dye to exclude platelets, unlysed red cells, and debris or use of 7-amino actinomycin D to exclude dead cells during data acquisition, 3) counterstaining with CD45 mAb to be included in the definition of HPC, 4) during list mode data analysis, Boolean gating to resolve the CD34+ HPCs from irrelevant cell populations on the basis of the low levels of CD45 expression and low sideward light-scatter signals of HPCs, 5) inclusion of CD34dim and CD34bright populations in the CD34+ cell count, 6) omission of the negative control staining, and 7) for apheresis products, enumeration of at least 100 CD34+ cells to ensure a 10% precision. Unresolved technical questions are 1) the replacement of conventional dual-platform by single-platform assay formats, i.e., derivation of absolute CD34+ cell counts from a single flow cytometric assessment instead of from combined flow cytometer (percent CD34+) and hematology analyzer (absolute leukocyte count) data, 2) the cross-calibration of the available single-platform assays, and 3) the optimal method for sample preparation. An important clinical question to be addressed is the definition of the precise phenotypes and required numbers of HPCs responsible for short- and long-term recovery to optimize HPC transplant strategies.

Mobilization of peripheral blood progenitor cells by disease-specific chemotherapy in patients with soft tissue sarcoma

We investigated peripheral blood progenitor cell (PBPC) mobilization by disease-specific chemotherapy in patients with metastatic soft tissue sarcoma (STS). Nine patients, five females and four males, aged 12-51 years, pretreated by one to nine courses of cytotoxic chemotherapy, underwent STS-specific mobilization followed by G-CSF at 5 microg/kg/day. PBPC were collected by 19 conventional-volume aphereses (8-12 l) with one to four procedures in individual patients. Leukaphereses started on median day 15 (range 13-18) from the first day of mobilization chemotherapy at medians of 25.8 x 10(3) WBC/microl (6.8-46.9), 3.5 x 10(3) MNC/microl (1.1-8.8), 122 x 10(3) platelets/microl (72-293) and 30.7 CD34+ cells/microl (6.7-207.8). Cumulative harvests resulted in medians of 4.6 x 10(8) MNC/kg (3.0-6.4), 2.9 x 10(6) CD34+ cells/kg (1.1-11.1) and 12.0 x 10(4) CFU-GM/kg (2.0-37.8). Eight patients underwent high-dose chemotherapy (HDCT) followed by PBPC rescue. Seven patients recovered hematopoiesis at medians of 12 days (8-15) for ANC >0.5 x 10(3)/microl and 14 days (8-27) for platelets >20 x 10(3)/microl. One patient, who received 1.6 x 10(6) CD34+ cells/kg, exhibited delayed ANC recovery on day +37 and failed to recover platelets until hospital discharge on day +55. We conclude that in patients with metastatic STS, who are pretreated by standard chemotherapy, PBPC can be mobilized by a further course of STS-specific chemotherapy plus G-CSF. One to four conventional-volume aphereses result in PBPC autografts that can serve as hematopoietic rescue for patients scheduled for HDCT.

[Flow cytometry quality control in stem cell separation]

Peripheral blood-derived haematopoietic stem cells (PBSC) are used as an alternative to bone marrow stem cells for autologous transplantation. One of the most important prerequisites for successful PBSC separation is the precise determination of the optimal separation days. As we previously demonstrated that neither PLT counts nor WBC counts in the peripheral blood (PB) are of predictive value for the amount of colony-forming cells (CFC) in the patients' PB, we started a daily monitoring of CD-34-positive cells to determine the beginning of the separation series. In addition to routine cell counts and CFU testing we assessed the number of CD 34+ in the PBSC concentrates to ascertain the number of separations needed for each patient. Due to the strong correlation of CD 34+ cells to CFC it is possible to predict the number of CFC collected within 2 h after finishing the PBSC separation and to calculate the efficiency of the separation for quality control.

Circulating CD34-expressing cells: German Proficiency Testing Survey

Determination of absolute numbers of CD34-expressing cells is critical in the setting of peripheral blood stem and progenitor cell transplantation/reinfusion. The diagnostic value of the parameter, CD34-expressing cells/microliter, has been validated. A survey of CD34-expressing cells has been integrated into a series of flow cytometry proficiency testing surveys (reticulocytes, lymphocytes, leukemia, and lymphoma) that we have established in Germany. Commercially available, modified, stabilized myeloblastic leukemia cells (KG1a cell line) spiked at different numbers into two normal blood samples were sent out, and report forms were returned from 50 of 58 participants. With a predicted percentage of CD34-expressing cells of 0.5% (sample A) and of 0.25% (sample B), the respective mean values analyzing data from 44 participants returning the completed forms were 0.49% (sample A) and 0.29% (sample B). The coefficients of variation were 57% and 83%, respectively. Engineered samples based on normal blood and on commercially available stabilized modified KG1a cells seem to be reliable material for external quality assessment surveys of CD34-expressing cells.

De novo malignancies after liver transplantation using tacrolimus-based protocols or cyclosporine-based quadruple immunosuppression with an interleukin-2 receptor antibody or antithymocyte globulin

BACKGROUND

Although conventional immunosuppression after liver transplantation consists of cyclosporine A (CsA), steroids, and azathioprine, recently introduced protocols entail CsA-based quadruple induction protocols or tacrolimus-based combinations. These protocols aim to reduce the rejection rate and the considerable morbidity related to the side effects of additional immunosuppressive treatment, but have not yet been analyzed regarding their long term de novo neoplastic risk.

METHODS

From September 1988 to May 1994, 500 liver transplantations were performed in 458 patients. The median follow-up was 50 months (range, 0.3-97 months) for all patients. Conventional triple therapy was implemented in 25 patients, CsA-based quadruple induction therapy using an antilymphocyte globulin preparation (ATG) in 190 patients, an interleukin-2 receptor antibody (BT563) in 141 patients, and tacrolimus-based dual or triple immunosuppression in 102 patients. The different protocols were evaluated in four randomized and two nonrandomized prospective trials.

RESULTS

De novo neoplasias were detected in 33 patients (7.2%) and were comprised of lymphomas (n = 7), skin malignancies (n = 8 lesions in 7 patients), intraepithelial neoplasias of the cervix uteri (n = 7), breast carcinoma (n = 3), lung carcinoma (n = 3), and other malignancies (n = 6). The incidence of de novo neoplasias did not differ in the different trial arms. Only a positive T-crossmatch and a low CD4+/CD8+ ratio in patients receiving CsA-based immunosuppression demonstrated a significant correlation with the development of a de novo tumor in a multivariant logistic regression analysis.

CONCLUSIONS

The development of de novo neoplastic diseases after liver transplantation with the use of CsA-based quadruple induction protocols or tacrolimus-based regimens for immunosuppresion was assessed over the long term. Recently introduced immunosuppressive protocols did not alter the posttransplant de novo tumor rate. Patients with a low CD4+/CD8+ ratio during CsA-based therapy or a positive T-crossmatch were identified to be at an increased risk for the development of a de novo malignancy.

De novo malignancies after liver transplantation using tacrolimus-based protocols or cyclosporine-based quadruple immunosuppression with an interleukin-2 receptor antibody or antithymocyte globulin

BACKGROUND

Although conventional immunosuppression after liver transplantation consists of cyclosporine A (CsA), steroids, and azathioprine, recently introduced protocols entail CsA-based quadruple induction protocols or tacrolimus-based combinations. These protocols aim to reduce the rejection rate and the considerable morbidity related to the side effects of additional immunosuppressive treatment, but have not yet been analyzed regarding their long term de novo neoplastic risk.

METHODS

From September 1988 to May 1994, 500 liver transplantations were performed in 458 patients. The median follow-up was 50 months (range, 0.3-97 months) for all patients. Conventional triple therapy was implemented in 25 patients, CsA-based quadruple induction therapy using an antilymphocyte globulin preparation (ATG) in 190 patients, an interleukin-2 receptor antibody (BT563) in 141 patients, and tacrolimus-based dual or triple immunosuppression in 102 patients. The different protocols were evaluated in four randomized and two nonrandomized prospective trials.

RESULTS

De novo neoplasias were detected in 33 patients (7.2%) and were comprised of lymphomas (n = 7), skin malignancies (n = 8 lesions in 7 patients), intraepithelial neoplasias of the cervix uteri (n = 7), breast carcinoma (n = 3), lung carcinoma (n = 3), and other malignancies (n = 6). The incidence of de novo neoplasias did not differ in the different trial arms. Only a positive T-crossmatch and a low CD4+/CD8+ ratio in patients receiving CsA-based immunosuppression demonstrated a significant correlation with the development of a de novo tumor in a multivariant logistic regression analysis.

CONCLUSIONS

The development of de novo neoplastic diseases after liver transplantation with the use of CsA-based quadruple induction protocols or tacrolimus-based regimens for immunosuppresion was assessed over the long term. Recently introduced immunosuppressive protocols did not alter the posttransplant de novo tumor rate. Patients with a low CD4+/CD8+ ratio during CsA-based therapy or a positive T-crossmatch were identified to be at an increased risk for the development of a de novo malignancy.

De novo malignancies after liver transplantation using tacrolimus-based protocols or cyclosporine-based quadruple immunosuppression with an interleukin-2 receptor antibody or antithymocyte globulin

BACKGROUND

Although conventional immunosuppression after liver transplantation consists of cyclosporine A (CsA), steroids, and azathioprine, recently introduced protocols entail CsA-based quadruple induction protocols or tacrolimus-based combinations. These protocols aim to reduce the rejection rate and the considerable morbidity related to the side effects of additional immunosuppressive treatment, but have not yet been analyzed regarding their long term de novo neoplastic risk.

METHODS

From September 1988 to May 1994, 500 liver transplantations were performed in 458 patients. The median follow-up was 50 months (range, 0.3-97 months) for all patients. Conventional triple therapy was implemented in 25 patients, CsA-based quadruple induction therapy using an antilymphocyte globulin preparation (ATG) in 190 patients, an interleukin-2 receptor antibody (BT563) in 141 patients, and tacrolimus-based dual or triple immunosuppression in 102 patients. The different protocols were evaluated in four randomized and two nonrandomized prospective trials.

RESULTS

De novo neoplasias were detected in 33 patients (7.2%) and were comprised of lymphomas (n = 7), skin malignancies (n = 8 lesions in 7 patients), intraepithelial neoplasias of the cervix uteri (n = 7), breast carcinoma (n = 3), lung carcinoma (n = 3), and other malignancies (n = 6). The incidence of de novo neoplasias did not differ in the different trial arms. Only a positive T-crossmatch and a low CD4+/CD8+ ratio in patients receiving CsA-based immunosuppression demonstrated a significant correlation with the development of a de novo tumor in a multivariant logistic regression analysis.

CONCLUSIONS

The development of de novo neoplastic diseases after liver transplantation with the use of CsA-based quadruple induction protocols or tacrolimus-based regimens for immunosuppresion was assessed over the long term. Recently introduced immunosuppressive protocols did not alter the posttransplant de novo tumor rate. Patients with a low CD4+/CD8+ ratio during CsA-based therapy or a positive T-crossmatch were identified to be at an increased risk for the development of a de novo malignancy.

Imprecision of counting CFU-GM colonies and CD34-expressing cells

Determinations of committed haemopoietic progenitor cells, namely CFU-GM (colony-forming unit-granulocyte/macrophage) and of CD34-expression haemopoietic cells as assessed by multiparameter flow cytometry are routine diagnostic tools in haemopoietic cell therapy. Generally, the tests are used to optimise the timing and management of cytapheresis and to assess the engraftment potential of the harvested cells. Both measurements, however, are at best surrogate markers, as an adequate routine test which effectively assesses the short- and long-term repopulating haemopoietic cell is not available. Nonetheless, cell threshold doses have been established. Above these thresholds rapid engraftment is almost invariable but below these thresholds the outcome is variable. In this study we have focussed on the imprecision in counting haemopoietic cells, as assessed as CFU-GM and as CD34-expressing cells. The data on both tests have been analysed from six European institutions. The coefficient of variation in CFU-GM colony counting was about 30%, whereas the coefficient of variation in flow cytometric counting of CD34-expressing cells was about 10%. These data suggest that the technical imprecision in enumerating progenitor cells, particularly CFU-GM, at low levels, might make a major contribution to the clinical variability observed after transplantation of sub-threshold progenitor cell dose.

Two subsets of peripheral blood plasma cells defined by differential expression of CD45 antigen

The purpose of this study was to optimize the flow cytometric determination of circulating normal and malignant plasma cells (PC). We investigated peripheral blood (PB) samples of 65 patients with multiple myeloma or monoclonal gammopathy of unknown significance and 47 control subjects using CD38, CD45, B-B4, CD56, VLA-4, VLA-5 and CD19 monoclonal antibodies (MoAbs). Mono- or polyclonality was determined by staining of intracellular kappa and lambda light chains. Two subpopulations of PBPC were distinguished by differential expression of CD45. CD45 positive (CD45+) PC showed a more immature morphology and were detected in all groups. They were polyclonal in the control subjects and either poly- or monoclonal in the myeloma patients. In contrast, CD45 negative (CD45-) PBPC only occurred in myeloma patients and were consistently monoclonal, their presence being significantly associated with high disease activity (P < 0.001). Although detection of CD45- PBPC using CD38 or B-B4 MoAbs lead to similar results. CD45+ PBPC often were recognized to a lesser extent by B-B4 than by CD38 MoAbs. In conclusion, normal and malignant circulating PC can reliably be identified using CD38 and CD45 MoAbs. CD45 expression separates PBPC into two subsets of which the CD45- one only occurs in myeloma patients.

Recent progress on the role of Axl, a receptor tyrosine kinase, in malignant transformation of myeloid leukemias

Receptor tyrosine kinases (RTK) play an important role in the signal transduction of normal and malignant cells. There are different families of RTKs which are mainly characterized by differences in the ligang-binding extracellular domains. Axl (or UFO/Ark) is the first member of a new class of RTK with two fibronectin type III domains and two immunoglobulin-like domains present at the extracellular domain. The axl-gene has been isolated by means of gene transfection studies using DNA of patients with chronic myelogeneous leukemia. For a previous and the present study, we used a sensitive reverse-transcriptase polymerase chain reaction assay to detect axl's mRNA in cells from normal and malignant hematopoietic tissue. Axl's mRNA expression was mainly detected in myelo-monocytic cells, whereas much weaker transcription was seen in lymphatic cells and in lymphatic leukemias. In normal bone marrow, axl was heavily transcribed in marrow stromal cells. Further, we analysed Axl protein expression using monoclonal antibody M50 in peripheral stem cell harvests; in most harvests, no co-expression of CD34 and Axl was detected. However, in one patient with AML in complete remission, Axl was co-expressed on 80% of the CD34-positive population. These data show that axl is preferentially expressed in monocytes and stromal cells. Furthermore, a fraction of CD34-positive progenitor cells may express Axl. The exact mechanism for transformation of myeloid progenitor cells through Axl, however, remains to be determined.

Peripheral blood progenitor cell collection during hematopoietic recovery following autologous blood progenitor cell transplantation

BACKGROUND AND OBJECTIVES

Peripheral blood progenitor cells (PBPC) are increasingly used for autologous transplantation after high-dose radio/chemotherapy in patients suffering from cancer. PBPC are usually collected after mobilization with conventional-dose chemotherapy plus growth factor. However, it is conceivable to perform leukapheresis for the second autograft during recovery of hematopoiesis after the first course of HDCT/ABPCT.

MATERIALS AND METHODS

We treated two patients this way. In the first, with germ cell cancer, six 12-liter leukaphereses yielded 1.8 x 10(6) CD34+ cells/kg after mobilization with cis-platinum, etoposide and ifosfamide (PEI) plus granulocyte colony-stimulating factor (G-CSF). The second patient, with relapsed Hodgkin's disease, underwent PBPC collection after treatment with dexamethasone, carmustine, etoposide, cytarabine and melphalan (DexaBEAM) plus G-CSF. Due to excellent mobilization, 8.5 x 10(6) CD34+ cells/kg were collected by one 12-liter leukapheresis. Both patients then underwent PBPC collection during hematopoietic recovery following HDCT and ABPCT.

RESULTS

In patient 1, following HDCT and ABPCT, three 12-liter aphereses resulted in 0.7 x 10(6) CD34+ cells/kg. In patient 2, also after HDCT and ABPCT, a second autograft with 3.2 x 10(6) CD34+ cells/kg was harvested by a single 10-liter apheresis. No adverse effects were seen in either patient during apheresis following ABPCT. To our knowledge this is the first report dealing with PBCT collection during hematopoietic recovery following HDCT and ABPCT.

CONCLUSIONS

(1) PBPC harvesting is feasible and well tolerated in this setting. (2) In appropriate patients with efficient PBPC mobilization after conventional-dose chemotherapy, a further PBPC autograft can be collected during recovery of hematopoiesis after ABPCT, serving as a rescue for a second course of HDCT.

In-vitro clonogenicity of mobilized peripheral blood CD34-expressing cells: inverse correlation to both relative and absolute numbers of CD34-expressing cells

The determination of CD34-expressing cells by multiparameter flow cytometry is now widely used to estimate the reconstitution potential of cells harvested by cytapheresis for peripheral blood stem cell and progenitor cell transplantation. There is a correlation between the number of CD34-expressing cells collected and committed progenitor cells (CFU-GM and BFU-E) capable of forming colonies in vitro, but there is considerable variation in the proportion of CD34-expressing cells capable of clonogenic growth. The data in this study of 782 cytapheresis samples indicates that there is a negative correlation between the clonogenicity of the CD34-expressing cells and the absolute number or the proportion of CD34-expressing cells within the harvest. In 116 samples the proportion of CD34-expressing cells co-expressing the CD45-RA-antigen (a subset of CD34-expressing cells which includes virtually all clonogenic cells in terms of CFU-GM) was determined, but this did not help to identify the clonogenicity of a given sample. These findings may have clinical relevance, particularly when mobilization is judged to be relatively poor or when a good harvest is to be divided for multiple high-dose procedures.

Expression of class I, II and III epitopes of the CD34 antigen by normal and leukemic hemopoietic cells

Peripheral blood samples from 115 consecutive patients and bone marrow samples from 9 healthy donors were studied for percentages of CD34-expressing cells, quantitative expression of various CD34 epitopes as defined by fluorescence mean channel, and mutual inhibition of the different CD34 monoclonal antibodies detecting the various CD34 epitopes. The study focused only on samples from patients with presumably elevated numbers of CD34-expressing cells, due to the nature of the disease. Samples from patients with chronic myeloproliferative syndromes, acute leukemias from nonhematological cancer patients during mobilization with filgrastim, and normal bone marrow samples were studied. Elevated numbers of CD34-expressing cells (> 0.04% of all nucleated cells) were detected in 111 of 124 patients. An almost identical expression of CD34 epitopes as detected by phycoerythrin-conjugated monoclonal antibodies QBEND-10, 8G12, and ICH3 were detected, whereas expression of the IMMU409 epitope was detected in only a few samples (19 of 111). Reactivity of IMMU-133 was almost identical to that of QBEND-10. Reactivity of BIRMA-K3, the only CD34 monoclonal used in this study, but not described in previous workshops, was almost identical to that of 8G12. From studies on mutual inhibition of binding, two families of CD34 epitopes are defined. The first family is comprised of QBEND-10, IMMU-133, My-10, and ICH-3, and the second one is comprised of only 8G12 and BIRMA-K3.

Interference of blood leucocytes in the measurements of immature red cells (reticulocytes) by two different (semi-) automated flow-cytometry technologies

Flow cytometrical methods have been introduced recently as an alternative to the enumeration of reticulocytes by microscopy. Two of these methods have gained widespread use in haematological practice; the multiparametric flow cytometer using thiazole orange staining (Retic-Count, FACScan) and the single-application reticulocyte counter using auramine-O staining (R-series, Sysmex). Several studies have emphasized the excellent correlations between microscopy and these techniques. The purpose of our study has been to examine the specificity of these automated devices with regard to cells classified as 'reticulocytes' and the effect that this may have on measures of reticulocyte maturity. Our results indicate that the specificity of reticulocyte measurements by both the Sysmex R-1000/-3000 and the Retic-Count system is relatively low. This is due to the presence of leucocytes amongst cells classified as reticulocytes. These leucocytes display intense staining with either dye, leading to an erroneous estimation of RMI (thiazole orange) and high fluorescence count (R-1000/-3000). This error is directly correlated with the leucocyte count. The basis for reticulocyte identification should be improved before automated estimation of reticulocyte maturation can be used in clinical practice.

Impact of preleukapheresis cell counts on collection results and correlation of progenitor-cell dose with engraftment after high-dose chemotherapy in patients with germ cell cancer

PURPOSE

To identify predictive factors for a good leukapheresis yield and to determine peripheral-blood progenitor cell (PBPC) dose requirements for rapid hematopoietic engraftment.

PATIENTS AND METHODS

Seventy-one patients with germ cell cancer (GCC) underwent PBPC harvest for autologous transplantation following high-dose therapy. Aphereses were performed after chemotherapy during granulocyte colony-stimulating factor (G-CSF) administration.

RESULTS

A median of two aphereses (range, two to five) resulted in 4.6 x 10(8) mononuclear cells (MNC)/kg, 15.7 x 10(4) colony-stimulating units granulocyte-macrophage (CFU-GM)/kg, and 6.0 x 10(6) CD34+ cells/kg. Peripheral blood MNC count correlated significantly with number of harvested CD34+ cells per kilogram (r = .49; P < .0001) and with CFU-GM count per kilogram (r = .35; P < .002). Circulating CD34+ cells from peripheral blood gave the best correlations to collected CD34+ cells per kilogram (r = .92; P < .0001), as well as to harvested CFU-GM per kilogram (r = .48; P < .0001). A preleukapheresis number of CD34+ cells greater than 4 x 10(4)/mL was highly predictive for a PBPC collection yield that contained more than 2.5 x 10(6) CD34+ cells/kg harvested by a single leukapheresis. After autologous transplantation, 41 patients were assessable for hematopoietic engraftment. They engrafted in a median time of 9 days (range, 7 to 18) to a WBC count greater than 1.0 x 10(9)/L, 10 days (range, 7 to 18) to an absolute neutrophil count (ANC) greater than 0.5 x 10(9)/L, and 11 days (range, 7 to 62) to a platelet (PLT) count greater than 20 x 10(9)/L. Good correlations were seen between reinfused CD34+ cell count and recovery of WBC count, ANC, and PLT count, with r values of .65 (P < .001), .65 (P < .001), and .45 (P < .03), respectively. Patients reinfused with a PBPC dose greater than 2.5 x 10(6) CD34+ cells/kg recovered hematopoiesis in a significantly shorter time than patients who received less than 2.5 x 10(6) CD34+ cells/kg.

CONCLUSION

Rapid hematopoietic engraftment can be achieved by a PBPC dose of greater than 2.5 x 10(6) CD34+ cells/kg. When circulating preleukapheresis CD34+ cell counts are greater than 4 x 10(4)/mL, a PBPC autograft that contains more than 2.5 x 10(6) CD34+ cells/kg can be collected by a single leukapheresis.

Autografting with blood progenitor cells: predictive value of preapheresis blood cell counts on progenitor cell harvest and correlation of the reinfused cell dose with hematopoietic reconstitution

One hundred and nine patients suffering from various malignancies underwent 285 apheresis procedures for PBPC collection. A median of two leukaphereses (range: 2-5) resulted in median numbers of 4.6 x 10(8) MNC/kg, 14.1 x 10(4) CFU-GM/kg, and 6.0 x 10(6) CD34+ cells/kg. Preleukapheresis peripheral blood CD34+ cells correlated significantly with collected CD34+ cells/kg (r = 0.94; p < 0.0001) and with CFU-GM/kg (r = 0.52; p < 0.0001). A value > 4 x 10(4) CD34+ cells/ml was highly predictive for a collection yield > 2.5 x 10(6) CD34+ cells/kg harvested by a single leukapheresis. Sixty patients were evaluated for hematologic reconstitution and engrafted in a median time of 10 days for WBC > 1.0 x 10(9)/l (range: 7-21 days), 10 days for ANC > 0.5 x 10(9)/l (7-20) and 11 days for PLT > 20 x 10(9)/l (7-62). Reinfused CD34+ cells/kg correlated significantly with hematologic engraftment (r = 0.44-0.52 and p < 0.006-0.001) as well as CFU-GM/kg (r = 0.36-0.44 and p < 0.007-0.001). A progenitor cell dose > 2.5 x 10(6) CD34+ cells/kg or > 8.0 x 10(4) CFU-GM/kg led to a significantly faster recovery for WBC, ANC, and PLT when compared with patients receiving < 2.5 x 10(6) CD34+ cells/kg or < 8.0 x 10(4) CFU-GM/kg. We conclude that rapid hematopoietic engraftment after high-dose therapy and PBPC reinfusion correlates well with a progenitor cell dose > 2.5 x 10(6) CD34+ cells/kg or > 8.0 x 10(4) CFU-GM/kg, and that above a preleukapheresis threshold of 4 x 10(4) CD34+ cells/ml a PBPC autograft containing > 2.5 x 10(6) CD34+ cells/kg can be collected by a single leukapheresis. We suggest that patients recovering from myelosuppression should be monitored for CD34+ cells in serial blood samples to determine the course of circulating hematopoietic progenitor cells. This issue will help to define the optimal time point to start apheresis and to predict a PBPC autograft harvested by a single leukapheresis, which will lead to rapid and stable hematopoietic reconstitution following transplantation.

Propagation of large numbers of cells of a human mixed-lineage T-lymphoid/myeloid

Previously, a subset of T cells co-expressing the myeloid antigen CD33 has been described in patients with acute myelogenous leukaemia. However, normal lymphocytes have been viewed as not expressing the CD33 antigen. We have developed culture conditions which allow for the rapid expansion of CD3+CD33+ cells from patients with myeloid leukaemia as well as normal individuals. The protocol for cellular expansion includes the addition of interferon-gamma on day 0, interleukin-1, interleukin-2 and a monoclonal antibody against CD3 on day 1 to peripheral blood lymphocytes. Using this protocol, total cell number increased more than 600-fold within 16 d of culture. Cells could be kept in culture for more than 6 months. Cells of the CD3+CD33+ phenotype increased to 15.2 +/- 4.6% using this protocol after 16 d in culture. These cells have been characterized by flow cytometry and have been found to express the alpha, beta T-cell receptor, co-express the CD2, CD5, CD7 and HLA-DR antigens and did not express CD14 or CD15 antigens. Cells of the CD3+CD33+ phenotype were unable to lyse tumour cells as determined in a 51Cr release assay. In patients with chronic myeloid leukaemia. CD3+CD33+ cells seem to be negative for expression of bcr/abl transcript in contrast to CD33- cells. Our data suggest that CD3+CD33+ cells do exist in peripheral blood from normal individuals.

Hematopoietic rescue after high-dose chemotherapy using autologous peripheral-blood progenitor cells or bone marrow: a randomized comparison

PURPOSE

To compare autologous bone marrow (BM) with peripheral-blood progenitor cells (PBPC) as hematopoietic rescue after high-dose chemotherapy (HDCT).

PATIENTS AND METHODS

From January 1991 until April 1993, 47 consecutive patients with relapsed or refractory germ cell tumors were randomized to either BM harvest or collection of PBPC mobilized by chemotherapy plus granulocyte colony-stimulating factor (G-CSF). After additional conventional-dose salvage treatment, all patients received HDCT with carboplatin 1,500 mg/m2, etoposide 2,400 mg/m2, and ifosfamide 10 g/m2 with either BM or PBPC rescue.

RESULTS

Forty-six patients were assessable for hematologic reconstitution, and one patient died on day +4 before engraftment. Rescue using PBPC resulted in a significantly shorter recovery time to neutrophil counts more than 500/microL (10.0 v 11.0 days, P < .01), neutrophil counts more than 1,000/microL (10.0 v 12.0 days, P = .001), and platelet counts more than 20,000/microL (10.0 v 17.0 days, P < .01), as well as in fewer days to transfusion independence from RBCs (8.0 v 12.0, P < .05) and platelets (9.0 v 12.0, P < .01) and fewer days of intravenous (IV) antibiotics (9.0 v 11.0, P < .05). However, no statistical differences in transfusion requirements or in other clinical outcome variables were observed. Overall survival and event-free survival also were not different in the two study arms.

CONCLUSION

We conclude that the use of PBPC mobilized by chemotherapy plus G-CSF results in sustained trilineage reconstitution after HDCT, which occurs more rapidly as compared with BM. The earlier hematologic reconstitution in patients with PBPC rescue significantly reduces the time to transfusion independence.