Blood stem cell collection: factors influencing the recovery of granulocyte-macrophage colony forming cells

We evaluated data from all blood cell (BC) collections performed in our institution between 1989 and 1995 to determine factors influencing the outcome of collection. One hundred and thirty-three collections were performed on 106 patients. Malignant diagnoses were: non-Hodgkins lymphoma (NHL) in 35%, multiple myeloma in 31%, breast cancer in 26%, and Hodgkin's disease in 8%. Collections were obtained routinely in myeloma and breast cancer and due to bone marrow involvement with malignancy or inaspirable bone marrow in lymphoma patients. Collections were obtained on a Cobe Spectra or Baxter-Fenwall CS3000+. Engraftment potential was determined by methylcellulose colony assay (CFU-GM), with a target of > 10 x 10(4) CFU-GM/kg. Apheresis nucleated cell count correlated significantly, albeit weakly (r = 0.26), with CFU-GM with a cell count of > 5 x 10(8)/kg resulting in an adequate number of CFU-GM in 78% of patients. In univariant analysis outcome of collection was significantly influenced by the patients age (p = 0.01), malignant diagnosis (p < 0.001), reason for collection (p = 0.002), and the mobilization regimen (p = 0.01). The nature of the apheresis device used did not influence outcome. Only malignant diagnosis was significant (p < 0.001) in multivariate analysis. We conclude that the outcome of BC is most strongly influenced by patient factors such as malignant diagnosis. These factors must be considered when comparing the outcome of different mobilization regimens and when planning collection strategies.

Peripheral blood progenitor cell collections in multiple myeloma: predictors and management of inadequate collections

Thirty-seven patients with previously treated multiple myeloma (MM) underwent peripheral blood progenitor cell (PBPC) collection following high-dose cyclophosphamide and GM-CSF or sequential IL-3 and GM-CSF. Patients with an inadequate collection were considered for a second or third collection. 25 patients underwent subsequent autotransplant. The only variable predictive of CFU-GM yield was the extent of prior melphalan therapy. All repeat collections were unsuccessful and patients infused with an autograft obtained from multiple sets of collections had a high incidence of delayed engraftment. We conclude that melphalan should be avoided or PBPC collection performed early in the disease course in patients who are potential transplant candidates.

The role of intensive therapy and autologous blood and marrow transplantation for chemotherapy-sensitive relapsed and primary refractory non-Hodgkin's lymphoma: identification of major prognostic groups

Patients with intermediate grade non-Hodgkin's lymphoma (NHL) who relapse or fail to achieve a complete remission after anthracycline-containing induction regimens have a poor outcome with conventional-dose salvage treatment. This outcome may be improved with intensive therapy and autologous transplantation (ABMT) but even in patients with proven chemotherapy-sensitive disease, relapse rates of up to 60% are observed. Reliable and powerful prognostic indicators are needed to identify appropriate patients for this expensive procedure and those subjects to whom alternative or additional treatment should be offered. We were interested in testing the hypothesis that tumour burden, and hence remission status immediately prior to transplant, is an important prognostic indicator of survival. We aggressively treated patients with conventional-dose salvage chemotherapy to maximum tumour response, and tested, by multivariate regression analysis, predictors of outcome post-transplant. We studied 81 consecutive patients with intermediate grade and immunoblastic NHL who achieved either a partial (PR) or complete remission (CR) following repetitive cycles of conventional-dose salvage therapy. Intensive therapy consisted of etoposide (60 mg/kg) and intravenous melphalan (160-180 mg/m2) with or without total body irradiation (TBI) followed by infusion of autologous unpurged bone marrow and/or blood cells. The predicted 4-year survival and progression-free survival (PFS) with a median follow-up of 37 months was 58% and 48% (95% confidence interval (CI) 37-55%), respectively. The only factor predictive of outcome was remission status at transplant (P=0.0001). The PFS at 4 years for the CR group was 61% (95% CI 53-75%). In contrast, only 25% (95% CI 11-40%) of patients undergoing autotransplant in PR were progression free at 4 years. We conclude that remission status at transplant after maximum tumour reduction is a powerful prognostic indicator.

Optimizing the CD34+ and CD34+Thy-1+ stem cell content of peripheral blood collections

We have previously described a sensitive and specific CD34 enumeration assay and report here a prospective analysis of 25 myeloma patients undergoing PBSC mobilization using this assay to determine the optimal days for collection of CD34+ and CD34+Thy-1+ cells after chemotherapy and growth factor mobilization. Correlations between frequency of peripheral blood CD34+ cells, circulating white blood cell (WBC) count, apheresis CD34+ cell count, nucleated cell count (NCC), and numbers of apheresis colony-forming units granulocyte/macrophage (CFU-GM) were determined. To assess levels of the more primitive subsets of CD34+ cells in the PBSC collections, coexpression of the Thy-1 antigen (CDw90) on CD34+ cells was also assessed. Marked heterogeneity was noted between patients with apheresis samples containing a median NCC of 4.2 x 10(8)/kg (range 1.3-8.1), median CFU-GM 17 x 10(4)/kg (range 0.15-32 x 10(4)/kg), and median CD34+ cell count of 1.39 x 10(6)/kg (range 0.02-6.6). The frequency of CD34+ cells in PBSC collections coexpressing Thy-1 was also heterogenous (6.2-50% of CD34+ cells), median 21.6%, mean 24.7 +/- 2%. The apheresis CD34+ cell count correlated with the peripheral blood CD34+ cell percentage (r = 0.71, p < 0.0001) but only weakly with the peripheral WBC. Apheresis CD34+Thy-1+ cell numbers correlated strongly with the circulating CD34+ cell numbers (r = 0.80), but no correlation was noted between these candidate stem cells and the peripheral WBC. In contrast, apheresis CFU-GM levels correlated most strongly with the peripheral WBC count (r = 0.61, p < 0.0001). The apheresis CD34+ cell count correlated with apheresis CFU-GM (r = 0.75, p < 0.0001) but not with the apheresis NCC. Apheresis CD34+Thy-1+ counts significantly correlated only with the apheresis CD34+ cell count and not with the apheresis CFU-GM or NCC. A higher percentage of circulating and apheresis CD34+ cells expressing Thy-1 were found on day 1 of collection, and the percentage of CD34+ cells expressing Thy-1 decreased on each subsequent day of measurement: median of 22% day 1 vs. 16.6% day 4, p = 0.04. This study therefore confirms that accurate quantitation of circulating CD34+ cells best predicts the optimal day for apheresis collection of CD34+ and CD34+Thy-1+ cells and is superior to the WBC count in this regard. Furthermore, the candidate stem cell (CD34+Thy-1+) subset is most prevalent during the earliest phases of CD34+ cell mobilization.

Mini-BEAM as salvage therapy for relapsed or refractory Hodgkin's disease before intensive therapy and autologous bone marrow transplantation

PURPOSE

To evaluate the efficacy of carmustine (BCNU), etoposide, cytarabine (Ara-C), and melphalan (mini-BEAM) as salvage therapy in patients with relapsed or refractory Hodgkin's disease who were potentially eligible to undergo intensive therapy and autologous bone marrow transplantation (ABMT).

PATIENTS AND METHODS

Forty-four patients with refractory or relapsed Hodgkin's disease after front-line combination chemotherapy referred for consideration of ABMT were treated with mini-BEAM (BCNU 60 mg/m2 on day 1, etoposide 75 mg/m2 on days 2 to 5, Ara-C 100 mg/m2 twice per day on days 2 to 5, and melphalan 30 mg/m2 on day 6) to maximum response. Eleven patients were refractory to primary chemotherapy. Twenty-three patients were treated in first relapse and 10 in second or subsequent relapse; 21 received mini-BEAM as their first salvage regimen. Patients were restaged to determine disease status immediately before intensive therapy and transplant.

RESULTS

The overall response rate was 84% (exact 95% confidence interval [CI], 70% to 92%), with a complete response (CR) rate of 32% (95% CI, 20% to 47%) and a partial response (PR) rate of 52%. No treatment-related deaths were observed. Myelosuppression was the major toxicity. Almost all patients required platelet transfusions. Eighty-four percent were given RBC transfusions, and 54% required intravenous antibiotics for fever while neutropenic.

CONCLUSION

Mini-BEAM is a safe and effective regimen for treatment of refractory or relapsed Hodgkin's disease. Further studies are required to determine if responding patients have improved disease-free survival (DFS) after intensive therapy and ABMT.

Microbial contamination of harvested bone marrow and peripheral blood

The incidence and clinical consequences of microbiological contamination of autologous bone marrow and peripheral blood progenitor cells are not well documented. We therefore retrospectively analysed our experience with bacterial or fungal contamination of harvested bone marrow and/or peripheral blood. From January 1987 to the end of January 1994, 499 patients were harvested or which 301 were transplanted. A total of 3910 specimens obtained during three stages in the processing were assessed for microbial contamination: (1) in the operating room immediately after harvesting (1662 bags) with 2.1% culture positivity, (2) after processing for cryopreservation (1039 bags) with a further 1.1% cultures positive, and (3) after thawing at the time of reinfusion (1209 bags) of which 2.2% were culture positive. There were no culture positive specimens obtained from any peripheral blood progenitor cell products. The vast majority of the 85 culture positive specimens obtained from marrow were skin flora (89%) and 35% of all positive harvest specimens remained positive following processing and freezing. At least 36% of culture positive specimens were thought to have arisen as a result of exogenous contamination of blood culture bottles. Potentially pathogenic enteric organisms were present in nine (0.2%) specimens and infusion of these organisms occurred in four cases. A further seven patients were reinfused with marrow culture positive for skin organisms. No adverse clinical sequelae were noted following infusion of any contaminated products. However, clinical decision making continues to be influenced by culture results and multistage microbial culture continues to be of value in the management of our marrow recipients.

Sensitive detection and enumeration of CD34+ cells in peripheral and cord blood by flow cytometry

Peripheral blood stem cell autografts are increasingly used to reconstitute hematopoiesis after intensive, potentially marrow-ablative therapy. Assessment of autograft adequacy by enumeration of hematopoietic progenitors in colony-forming assays is handicapped by lack of reproducibility and prolonged assay time. Alternative approaches of graft assessment by flow-cytometric enumeration of stem/progenitor cells bearing the CD34 antigen can be hampered by low specificity and sensitivity. Here, we report a rapid and reliable multiparameter flow-cytometric approach to accurately enumerate CD34+ cells in peripheral blood (PB) mononuclear cells (MNCs). Total nucleated white blood cells (WBCs) are quantified by staining with fluorescein isothiocyanate (FITC)-conjugated CD45 antibody. Simultaneous staining by phycoerythrin (PE)-conjugated CD34 antibody defines an approximate number for the CD34+ progenitor/stem cell subfraction. When starting CD34+ cell numbers are low (0.01-0.5%), other nonspecifically stained leukocytes make accurate enumeration impossible. However, when the CD34+ fraction is analyzed for CD45 expression vs. side scatter (granularity), true CD34+ blast cells form a discrete cluster exhibiting low-density CD45 expression and low side-scatter characteristics. Cells within this "blast region" can be readily distinguished from lymphocytes, monocytes, granulocytes, and other events that can contaminate the CD34+ population. Here, we used this sensitive procedure to enumerate CD34+ cells in steady-state PB samples (0.03-0.09%), normal bone marrow (BM) aspirates, and umbilical cord blood collections (0.33-1.98%). This approach thus provides a means to analyze CD34+ cells in specimens from patients who have been extensively treated with chemotherapy and those undergoing PB stem cell mobilization with cytokines. Additionally, it is useful for assessment of CD34+ cells in a variety of clinical samples exhibiting perturbations of the hematopoietic progenitor/stem cell compartments.

Germline complexity, restriction fragment length polymorphism, and coding region sequences of the human VH7 gene family identified with family-specific FR3 segment oligonucleotides

We have used the most family-specific gene segment, the 5'-end of framework 3 (FR3) to study the germline complexity and coding region sequences of the recently described human VH7 gene family. Because of the high degree of 5' sequence homology between members of the VH7 and VH1 families, full-length coding region probes are unable to distinguish between the two groups. Hybridization with a VH7 coding region probe to EcoRI digested genomic DNA revealed 12 fragments. Many of these hybridizing fragments were also identified with a full length VH1 coding sequence probe. However, examination of the same DNA samples with a VH7 family specific oligonucleotide, encompassing the 5'-end of the FR3 segment, greatly reduced hybridization complexity yielding only four fragments which included one polymorphic band of molecular weight 7.4 kb. The VH7 specific FR3 oligonucleotide was also used under conditions of moderate stringency to isolate VH7 clones from PCR-amplified genomic DNA libraries derived from six unrelated individuals. All clones isolated contained members of the VH7 family. Six sequences were obtained. Gene 7A.4, seen in all individuals, is identical to the previously described germline V1-4.1b gene other than G-C substitutions at nucleotides 253 and 254. Five distinct pseudogenes were also identified. Stop codons were confined to frameworks 2 and 3. Previously described expressed VH7 genes from cord blood, normal adults and two rheumatoid factors are > 96% homologous to gene 7A.4.

Immunoglobulin V regions and the B cell

There is now substantial evidence that a small group of V genes predominates in the Ig repertoire of preimmune B cells. This phenomenon of V gene restriction may reflect preferential accessibility of these genes to recombinase, homology-directed V gene rearrangement, promoters and enhances of V gene transcription, or positive and negative selection mediated by the anti-self binding properties of the B cells surface Ig. These mechanisms may operate alone or in combination to influence V gene rearrangement and populations of immature B cells. Although constraints on the pool of rearranged V genes may seem disadvantageous to the immune system, the mechanisms that generate the CDR3s of heavy and light chains ensure extensive diversity in the pre-B-cell population. In mature B cells, somatic mutation of V genes adds further diversity. CDR3 sequences and somatic mutations not only provide potentially useful clonal markers but also help to identify the normal counterparts of malignant B cells.

CD34 antigen: molecular features and potential clinical applications

Despite the wide variety of functions exhibited by mature peripheral blood cells, all are derived from a small pool (1-3%) of primitive precursor cells in the bone marrow (BM) that bear a unique surface glycoprotein, CD34. Isolated CD34+ cells are capable of reconstituting all hematopoietic lineages, both in experimental animals and in humans following intensive therapy. CD34+ cells capable of reconstituting hematopoiesis are also found at low frequency in peripheral blood (PB), a frequency which can be dramatically increased by combinations of chemotherapy and recombinant cytokines. In some cases, PB "stem cells" (PBSC) can be used to augment or even replace conventional BM autografts. The availability of CD34 antibodies has greatly aided the development of techniques for the enrichment of primitive progenitor cells, thus allowing studies of the hematopoietic potential of stem cells in vitro. Additionally, the use of CD34 antibodies for the "positive selection" of hematopoietic stem/progenitor cells from tumor-contaminated marrow may possibly represent an alternative "purging" strategy prior to transplantation. The availability of pure populations of the most primitive hematopoietic progenitor cells will also facilitate study of genetic manipulation as a practical therapeutic modality.

Extensive cutaneous plasmacytomas

An unusual case of extensive cutaneous and subcutaneous plasmacytomas is reported. Breast involvement was also a feature in this individual. The relevant literature relating to this unusual presentation of myeloma is reviewed.

Restriction fragment length polymorphisms and single germline coding region sequence in VH18/2, a duplicated gene encoding autoantibody

In this study, we analyze the restriction fragment length polymorphisms of VH18/2, a gene encoding the heavy chain of an anti-DNA antibody, and correlate that with the germline sequence of the gene's coding region. Oligonucleotides probes complementary to the CDR1 and to both the 5' and 3' halves of the CDR2 gene segments were hybridized under stringent conditions to genomic DNA digested with XbaI, and yielded polymorphic bands of 26, 24 and 18 kb with all three probes. Individuals had either one, two, or three bands in common in their genomic DNA, indicating duplication of VH18/2 genes at two sites within the IgH locus. While it is difficult to say which of the three polymorphic gene segments constitute an allelic pair, the 26 and 24 kb fragments were the most commonly seen (97% of individuals had one or both). VH18/2 is known to be over-represented in the expressed repertoire with very little nucleotide divergence from the germline sequence. In order to determine whether the observed RFLPs are due to sequence polymorphism of the VH18/2 coding region, and whether differences in the expressed genes arise from somatic mutation, size-selected genomic DNA containing the gene was cloned and sequenced. A single coding region sequence was found in the germline. The results of this study suggest that overexpression of VH18/2 may in part be due to its duplication. Like other genes encoding autoantibody, which are well conserved, nonpolymorphic and expressed early in programmed immunologic development, VH18/2 may be instrumental in the establishment or regulation of the immune repertoire.

High-frequency representation of a single VH gene in the expressed human B cell repertoire

Idiotype (Id) 16/6 marks a variable (V) region structure that occurs frequently in the human immunoglobulin repertoire. The basis of the Id has been traced to a germline heavy chain gene segment, VH18/2 (VH26). To pursue the molecular basis for the frequency of Id 16/6, we have analyzed polymerase chain reaction-generated C mu, C gamma, and VH3 family V gene libraries derived from the circulating and tonsillar B cells of four normal individuals and from the B cells of two patients with active systemic lupus erythematosus (SLE). The frequency of VH18/2 in these libraries was compared with three control VH genes, VH56P1, VH21/28, and VHA57. Plaque lifts from C mu and C gamma VH cDNA libraries were screened with gene-specific oligonucleotide probes. The frequency of VH18/2 ranged from 4 to 10% of JH+ plaques (two of five times that of control VH genes). In four VH3 family-specific libraries derived from rearranged DNA, VH18/2 represented 19-33% of VH3+ plaques. Hybridizing VH18/2 plaques were 98-100% homologous to the germline VH gene; mutations when present were often in framework 3. Extensive variation was seen in the complementarity determining region 3 sequences of these rearranged V genes. The high frequency of VH18/2 expression in the B cell repertoire was confirmed by sequencing randomly picked JH+ plaques. In two patients with active SLE the frequency of use of VH18/2 was not greater than that observed in normal subjects. These results show that VH18/2 is overrepresented in the B cell repertoire of normal subjects and suggest that the immune repertoire may be dominated by relatively few V genes.

VH-gene representation in autoantibodies reflects the normal human B-cell repertoire

The recurrence in the V-gene repertoire of individual germline VH genes can now be extended from the restricted B-cell populations of the fetus, autoantibodies and B-cell malignancies to the expressed V-gene repertoire of normal adults. Why the human B cell preferentially utilizes these individual VH genes remains speculative. However, it is apparent that the population of VH genes used to encode autoantibodies reflects the normal expressed repertoire (Fig. 7). Even so, the overrepresentation of other V genes such as Dxp'1 in anti-DNA antibodies and the presence of somatic mutation in the pathogenic autoantibodies of autoimmune disease continues to suggest an antigenic influence on V-gene selection. We postulate that only a fraction of available germline V genes are utilized in the expressed repertoire, and that polyspecificity of naturally occurring antibodies and somatic mutation of CDR3 compensate for the loss of diversity entailed by the limited use of the potential repertoire. The mechanisms by which germline genes become pathogenic remains unclear but they presumably relate to mutation, loss of regulatory control or perhaps environmental factors (Isenberg et al. 1992). What then are the mechanisms which lead to escape of these VH genes from normal control? What antigenic drive if any produces anti-DNA specificity in SLE? Why indeed is the expressed repertoire using only a fraction of the available germline? To answer these questions, further study of the V-gene repertoire of selected populations of antigen-binding cells and of pathogenic IgG autoantibodies is necessary and is ongoing. The contribution of individual V genes to antigen binding and idiotype is also being dissected and promises to yield important information about the relative contribution of VH genes to autoimmunity.

Immunoglobulin heavy chain gene expression in peripheral blood B lymphocytes

cDNA libraries for IgM heavy chain variable regions were prepared from unmanipulated peripheral blood lymphocytes of two healthy people. Partial sequencing of 103 clones revealed VH gene family use and complete CDR3 and JH sequences. The libraries differed in the two subjects. In one person's cDNA the VH5 family was overexpressed and the VH3 family underexpressed relative to genomic complexity. In the second person's cDNA, VH3 was most frequently expressed. In both libraries, JH4 was most frequent. VH segments of several clones were closely related to those in fetal repertoires. However, there was also evidence of mutation in many cDNAs. Three clones differed from the single nonpolymorphic VH6 germline gene by 7-13 bases. Clones with several differences from VH5 germline gene VH251 were identified. CDR3 segments were highly diverse. JH portions of several CDR3's differed from germline JH sequences. 44% of the clones had DH genes related to the DLR and DXP families, most with differences from germline sequences. In 11 DLR2-related sequences, several base substitutions could not be accounted for by polymorphism. Thus, circulating IgM-producing B cell populations include selected clones, some of which are encoded by variable region gene segments that have mutated from the germline form.

Acute leukemia evolving from multiple myeloma and co-expressing myeloid and plasma cell antigens

This report describes the development of acute myeloblastic leukemia in a patient after long-term alkylator therapy for multiple myeloma. Despite chromosome deletions -5, -7, the patient lacked the histochemistry and clinical findings characteristic of therapy-induced leukemia. In double-labeled surface marker studies by flow cytometry, the leukemic blast cells co-expressed myeloid and plasma cell surface markers. The findings may support the hypothesis of a single stem cell abnormality's being responsible for both the malignant plasma cells and the myeloid leukemic cells.

Acquired von Willebrand disease associated with free lambda light chain monoclonal gammopathy, normal bleeding time and response to prednisone

We report a case of acquired von Willebrand's syndrome with severe gastrointestinal bleeding and associated free monoclonal lambda light chains. The patient had a rapid sustained clinical and laboratory response to the administration of prednisone. Of note in this patient was the occurrence of angiodysplasia which has previously been reported in association with acquired von Willebrand's syndrome. No inhibitors of VWF:Ag, VWF:RCoF, or factor VIII:C were detected by mixing studies and the bleeding time was normal. Very few high molecular weight von Willebrand multimers were present prior to prednisone; however, the pattern reverted to a normal distribution following treatment. In appropriate patients with acquired von Willebrand's syndrome and monoclonal para-proteins, a trial of prednisone may be indicated.

Hypokalemia of unknown aetiology complicating Hodgkin's disease

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