Benefit of continuous treatment for responders with newly diagnosed multiple myeloma in the randomized FIRST trial.

The phase 3, randomized Frontline Investigation of Revlimid and Dexamethasone Versus Standard Thalidomide (FIRST) trial investigating lenalidomide plus low-dose dexamethasone until disease progression (Rd continuous) vs melphalan, prednisone and thalidomide for 12 cycles (MPT) and Rd for 18 cycles (Rd18) in transplant-ineligible patients with newly diagnosed multiple myeloma (NDMM) showed that Rd continuous prolonged progression-free survival and overall survival compared with MPT. A subanalysis of the FIRST trial was conducted to determine the benefits of Rd continuous in patients with NDMM based on depth of response. Patients randomized 1:1:1 to Rd continuous, Rd18 or MPT were divided into subgroups based on best response: complete response (CR; n=290), ⩾very good partial response (VGPR; n=679), ⩾partial response (PR; n=1 225) or ⩽stable disease (n=299). Over 13% of patients receiving Rd continuous who achieved ⩾VGPR as best response did so beyond 18 months of treatment. Rd continuous reduced the risk of progression or death by 67%, 51% and 35% vs MPT in patients with CR, ⩾VGPR and ⩾PR, respectively. Similarly, Rd continuous reduced the risk of progression or death by 61%, 54% and 38% vs Rd18 in patients with CR, ⩾VGPR and ⩾PR, respectively. In patients with CR, ⩾VGPR or ⩾PR, 4-year survival rates in the Rd continuous arm (81.1%, 73.1% or 64.6%, respectively) were higher vs MPT (70.8%, 59.8% or 57.2%, respectively) and similar vs Rd18 (76.5%, 67.7% and 62.5%, respectively). Rd continuous improved efficacy outcomes in all responding patients, including those with CR, compared with fixed duration treatment.

Myelofibrosis patients in Belgium: disease characteristics.

OBJECTIVE: To date, only a small number of epidemiological studies on myelofibrosis have been performed. The current study aimed to characterize the myelofibrosis patient population in Belgium according to pre-defined disease parameters (diagnosis, risk categories, hemoglobin <10 g/dl, spleen size, constitutional symptoms, platelet count, myeloblast count), with a view to obtaining a deeper understanding of the proportion of patients that may benefit from the novel myelofibrosis therapeutic strategies. METHODS: A survey was used to collect data on prevalence and disease parameters on all myelofibrosis patients seen at each of 18 participating hematologic centers in 2011. Aggregated data from all centers were used for analysis. Analyses were descriptive and quantitative. RESULTS: A total of 250 patients with myelofibrosis were captured; of these, 136 (54%) were male and 153 (61%) were over 65 years old. One hundred sixty-five (66%) of myelofibrosis patients had primary myelofibrosis and 85 (34%) had secondary myelofibrosis. One hundred ninety-three myelofibrosis patients (77%) had a palpable spleen. About a third of patients (34%) suffered from constitutional symptoms. Two hundred twenty-two (89%) myelofibrosis patients had platelet count ≧50 000/µl and 201 (80%) had platelet count ≧100 000/µl. Of 250 patients, 85 (34%) had a myeloblast count ≧1%. Six (2%) patients had undergone a splenectomy. Thirteen (5·2%) patients had undergone radiotherapy for splenomegaly. CONCLUSIONS: The results of this survey provide insight into the characteristics of the Belgian myelofibrosis population. They also suggest that a large proportion of these patients could stand to benefit from the therapies currently under development.

Lenalidomide in relapsed refractory myeloma patients: impact of previous response to bortezomib and thalidomide on treatment efficacy. Results of a medical need program in Belgium.

The prognosis of multiple myeloma patients has significantly improved since the introduction of the novel agents thalidomide, bortezomib and lenalidomide. We report the data of a medical need programme with lenalidomide plus dexamethasone, conducted in Belgium between August 2007 and March 2008, and including 98 relapsed refractory multiple myeloma patients. In addition to chemotherapy and steroids, all patients had received prior treatment with bortezomib, and 84% of them had been exposed to thalidomide. In 52 patients response data could be retrieved by post-hoc analysis. A partial remission or better was achieved in 52% (49% partial and 3% complete response) of patients, despite a median of 5 previous anti-myeloma treatment lines. Responses were rapid while the majority of patients received lenalidomide with once weekly (also called low-dose) dexamethasone. Treatment with lenalidomide plus dexamethasone did prolong overall survival by nearly half a year in this population with end-stage myeloma. Overall response and quality of response were independent of previous response to thalidomide and bortezomib, although the time to progression tended to be shorter in thalidomide- and bortezomib-refractory patients. It can be concluded that lenalidomide plus dexamethasone is an effective and safe treatment regimen in highly refractory multiple myeloma patients, and that these responses are irrespective of previous exposure or sensitivity to thalidomide and bortezomib.

Intensified chemotherapy inspired by a pediatric regimen combined with allogeneic transplantation in adult patients with acute lymphoblastic leukemia up to the age of 40.

Event-free survival (EFS) at 5 years in pediatric acute lymphoblastic leukemia (ALL) is >80%. Outcome in adult ALL is still unsatisfactory, which is due to less cumulative dosing of chemotherapy and less strict adherence to timing of successive cycles. In the present phase II trial, we evaluated a pediatric regimen in adult patients with ALL under the age of 40. Treatment was according to the pediatric FRALLE approach for high-risk ALL patients and characterized by increased dosages of asparaginase, steroids, methotrexate and vincristin. However, allogeneic stem cell transplantation was offered to standard risk patients with a sibling donor and to all high-risk patients in contrast to the pediatric protocol. Feasibility was defined by achieving complete remission (CR) and completion of treatment within a strict timeframe in at least 60% of patients. In all, 54 patients were included with a median age of 26. CR was achieved in 49 patients (91%), of whom 33 completed treatment as scheduled (61%). Side effects primarily consisted of infections and occurred in 40% of patients. With a median follow-up of 32 months, EFS estimated 66% at 24 months and overall survival 72%. These data show that a dose-intensive pediatric regimen is feasible in adult ALL patients up to the age of 40.

The Belgian 2010 consensus recommendations for the treatment of multiple myeloma.

Since the introduction of novel therapeutic agents including thalidomide, lenalidomide and bortezomib, the prognosis of multiple myeloma (MM) has significantly improved. These agents have been incorporated into numerous treatment schedules for newly diagnosed as well as more advanced MM patients. Hence, the therapeutic options for MM have become more complex and subject to rapid changes. The multiple myeloma study group (MMSG) of the Belgian Hematological Society has established recommendations for the treatment of MM as based on an extensive review of the literature which is also summarized in this paper. The recommendations are the result of a consensus opinion between haematologists with experience in the field and representing most haematology centres in Belgium. Where applicable, reimbursement criteria are also taken into account. The consensus recommendations should be a reference for use by clinical haematologists in daily practice.

Translocation t(1;6)(p35.3;p25.2): a new recurrent aberration in "unmutated" B-CLL.

Although reciprocal chromosomal translocations are not typical for B-cell chronic lymphocytic leukemia (B-CLL), we identified the novel t(1;6)(p35.3;p25.2) in eight patients with this disorder. Interestingly, all cases showed lack of somatically mutated IgV(H). Clinical, morphological, immunologic, and genetic features of these patients are described. Briefly, the age ranged from 33 to 81 years (median: 62.5 years) and the sex ratio was 6M:2F. Most of the patients (6/8) presented with advanced clinical stage. Therapy was required in seven cases. After a median follow-up of 28 months, five patients are alive and three died from disease evolution. Three cases developed transformation into diffuse large B-cell lymphoma. Translocation t(1;6) was found as the primary karyotypic abnormality in three patients. Additional chromosomal aberrations included changes frequently found in unmutated B-CLL, that is, del(11)(q), trisomy 12 and 17p aberrations. Fluorescence in situ hybridization analysis performed in seven cases allowed us to map the t(1;6) breakpoints to the 1p35.3 and 6p25.2 chromosomal bands, respectively. The latter breakpoint was located in the genomic region coding for MUM1/IRF4, one of the key regulators of lymphocyte development and proliferation, suggesting involvement of this gene in the t(1;6). Molecular characterization of the t(1;6)(p35.3;p25.2), exclusively found in unmutated subtype of B-CLL, is in progress.

Variant t(2;11)(p11;q13) associated with the IgK-CCND1 rearrangement is a recurrent translocation in leukemic small-cell B-non-Hodgkin lymphoma.

Classical t(11;14)(q13;q32) involving IGH-CCND1 is typically associated with aggressive CD5-positive mantle cell lymphoma (MCL). Recently, we identified the IGK variant of this translocation, t(2;11)(p11;q13), in three patients with a leukemic small-cell B-non-Hodgkin lymphoma. In all cases, rearrangements of the IGK and CCND1 genes were demonstrated by fluorescence in situ hybridization. Moreover, we mapped the 11q13 breakpoint of this variant translocation in the 3' region of CCND1 which contrasts with the 5' breakpoints in a standard t(11;14)(q13;q32). Expression of cyclin D1 was shown in two cases analyzed either at diagnosis or during disease progression. All three patients were asymptomatic at presentation and no initial therapy was required. One patient died of a progressive disease 58 months from diagnosis, and two patients showed stable disease after 12 months of follow-up. In two analyzed cases, mutated IGVH genes were identified. Our findings indicate that variant t(2;11)(p11;q13) does not typify a classical MCL but possibly a more indolent leukemic lymphoma originating from an antigen experienced (mutated) B cell.

Survival and freedom from progression in autotransplant lymphoma patients is independent of stem cell source: further follow-up from the original randomised study to assess engraftment.

Peripheral blood progenitor cells (PBPCs) have become the stem cell source of choice in autologous transplantation. In a prospective randomised trial, we previously demonstrated that autologous transplantation using filgrastim-mobilised PBPCs resulted in faster haematopoietic recovery with shorter hospitalisation and reduced platelet transfusions compared to bone marrow transplant (BMT). This study is a follow-up analysis evaluating the long-term clinical outcome. Seventy-two patients with advanced Hodgkin's disease or high-grade lymphoma were randomised to receive either filgrastim-mobilised PBPCs (n = 37) or bone marrow (n = 35) after BEAM chemotherapy. Fourteen patients withdrew from the study before commencing high-dose chemotherapy. Fourteen of the 58 patients who received treatment with chemotherapy and transplant have died, 6 (19%) in the ABMT arm and 8 (30%) in the PBPC transplant (PBPCT) arm. Twenty-five patients (81%) in the ABMT arm and 17 (63%) in the PBPCT arm, who received treatment, were in complete remission at the date of last follow-up. Progression-free survival and overall survival (OS) were similar for both arms (OS 81% at 46 months for ABMT versus 63% for PBPC; p = 0.38). Further prospective studies with larger number of patients need to be done to assess which source of stem cells may translate into a long-term clinical benefit for the patient.

Autopsy-controlled prospective evaluation of serial screening for circulating galactomannan by a sandwich enzyme-linked immunosorbent assay for hematological patients at risk for invasive Aspergillosis.

Efforts to improve the diagnosis of invasive aspergillosis (IA) have been directed towards the detection of fungal antigens, including galactomannan (GM). However, previous evaluations of GM detection have been hampered by a lack of proven cases of IA and by a nonserial study design. This prospective study assessed the diagnostic value of serial screening for circulating GM by using a recently developed sandwich enzyme-linked immunosorbent assay (ELISA) for prolonged-neutropenic and/or steroid-treated patients with hematological disorders. Serum GM levels were monitored twice weekly for 186 consecutive patients at increased risk for IA. The patients were stratified according to the likelihood of IA (proven, probable, possible, and no evidence of IA) by using stringent criteria. Proven IA was defined by characteristic histopathological findings together with a positive culture for Aspergillus species. Autopsy and culture from autopsy specimens was used to verify both positive and negative test results. A total of 2,172 serum samples were tested from 243 episodes (mean, 9 samples/episode). Based on the analysis of 71 patients with confirmed disease status (culture and histology), the sensitivity and specificity of serial GM monitoring were 92.6 and 95.4%, respectively. The positive predictive value was almost 93%, the negative predictive value was 95%, and the efficacy was 94%. False-positive reactions occurred at a rate of nearly 8%, although this figure might have been overestimated. Less than 1% of all tested sera were considered inconclusive. In more than half of the cases, antigenemia was detected before clinical suspicion of IA (median, 6 days before). Serial determination of serum GM by the sandwich ELISA technique is a sensitive tool for the diagnosis of IA in hematological patients at risk. This approach may substantially influence clinical management with regard to preemptive and empirical antifungal therapy.

Mucormycosis in allogeneic bone marrow transplant recipients: report of five cases and review of the role of iron overload in the pathogenesis.

In a 10-year consecutive series of 263 allogeneic bone marrow transplant recipients, we identified five cases (1.9%) of invasive mucormycosis. Only one infection occurred within the first 100 days after transplantation, while the remainder complicated the late post-transplant course (median day of diagnosis: 343). Sites of infection were considered 'non-classical' and included pulmonary, cutaneous and gastric involvement. No case of fungal dissemination was observed. Mucormycosis was the primary cause of death in three of the five patients. Corticosteroid-treated graft-versus-host disease, either acute or chronic, or severe neutropenia were present in all cases. However, compared with a matched control population, the most striking finding was the demonstration of severe iron overload in each of the mucormycosis patients. The mean level of serum ferritin, transferrin saturation and number of transfused units of red cells (2029 microg/l, 92% and 52 units, respectively) in the study group is significantly higher compared with the control group (P < 0.05). The difference with other risk groups for mucormycosis, including deferoxamine-treated dialysis patients and acidotic diabetics, was analyzed in view of the possible pathogenic role of iron. Although these infections are often fatal, limited disease may have a better prognosis if diagnosed early and treated aggressively.

The belgian experience in unrelated donor bone marrow transplantation: identification of center experience as an important prognostic factor.

BACKGROUND AND OBJECTIVE: We reviewed all unrelated donor bone marrow transplants (UDBMT) performed in Belgium up to December 1995 to identify prognostic factors for relapse, transplant-related mortality and survival. DESIGN AND METHODS: A total of 163 UDBMT were performed in 92 males and 71 females aged 1-55 (median 26) years. Patients were transplanted for ALL (n=35), AML (n=34), CML (n=51), other myeloid malignancies (n=14), SAA (n=21) or miscellaneous other diseases (n=8). Most patients had advanced disease; a few patients were in CR1 (n=10) or early chronic phase (CP) of CML (n=5). RESULTS: Overall survival at 5 yrs was 17% (95% confidence interval: 8-32%), but survival was significantly better for patients with non-malignant disorders (55% at 4 yrs). The relapse rate +/-SE was projected to be 40 (28-54)% at 5 yrs, 36 (20-56)% for standard-risk and 68 (43-85)% for high-risk malignancies (p=0.0029). There was no relapse in CML patients transplanted in 1st CP compared to 68% at 4 yrs with more advanced CML (p=0.0033). Grade II-IV acute graft-versus-host disease (aGVHD) occurred in 55% by day 100 and was strongly modulated by age, ranging from 41% in <20-yr-old to 80% in >40-yr-old patients (p=0. 0021). Transplant-related mortality (TRM) was projected to be 72 (52-87)% at 5 yrs including 2 very late deaths from lung fibrosis and secondary cancer. Main causes of death were original disease in 27, secondary malignancy in 2, GVHD in 28, interstitial pneumonia in 21, other infections in 19, and miscellaneous toxic causes in 21 patients. In multivariate analysis, the relapse rate was strongly dependent on the disease status (p=0.0029), TRM being significantly worse with older age (p=0.0049), and overall survival being significantly worse in more advanced disease (p=0.0006), after a second transplant (p=0.0166), in centers of smaller size (p=0.0316) and in older patients (NS). INTERPRETATION AND CONCLUSIONS: Although results have improved somewhat in recent years, UDBMT remains a procedure with a high TRM. UDBMT should be performed in patients with less advanced diseases and in centers with more experience, particularly in the treatment of adult patients.

Incidence and outcome of hepatic veno-occlusive disease after blood or marrow transplantation: a prospective cohort study of the European Group for Blood and Marrow Transplantation. European Group for Blood and Marrow Transplantation Chronic Leukemia Working Party.

To determine the incidence and outcome of hepatic veno-occlusive disease (VOD) after blood or marrow transplantation (BMT), we prospectively evaluated all consecutive patients receiving a BMT during a 6-month period in participating EBMT centers. All of them were evaluated for occurrence of VOD according to previously defined clinical criteria. The clinical course, outcome, value of prophylactic and therapeutic interventions, and the influence of previously described risk factors were analyzed. During the study period, 1,652 BMT were performed in 73 centers. VOD was diagnosed in 87 patients (5.3%; 95% confidence interval [CI], 4.2% to 6.4%). Fifty-six of 631 allogeneic BMT (8.9%) and 31 of 1,010 autologous BMT (3.1%) developed this complication (P <.0001). VOD was classified as mild in 7 (8%), moderate in 56 (64.4%), and severe in 24 (27.6%) cases. Sixteen patients died of VOD (corresponding to 1% of the whole series, 18.4% of VOD patients, and 66.7% of severe VOD). The use of unfractionated heparin did not significantly decrease the incidence of VOD. Independent variables associated with an increased risk of VOD were allogeneic BMT (relative risk [RR], 2.8; P <.001), pre-BMT elevation of serum aspartate aminotransferase (RR, 2.4; P =.001), high-dose cytoreductive therapy (RR, 2.3; P =.003), Karnofsky performance score less than 90% (RR, 2.7; P =.006), and prior abdominal radiation (RR, 2.9; P =.03). In conclusion, this prospective study shows that (1) the incidence of VOD is lower than that reported in smaller studies from single centers, (2) about one fourth of cases of VOD progress to severe disease, (3) main risk factors have a major impact on incidence of VOD, and (4) the use of prophylactic unfractionated heparin does not seem to reduce the incidence of VOD.

Lymphocyte profiles in multiple myeloma and monoclonal gammopathy of undetermined significance: flow-cytometric characterization and analysis in a two-dimensional correlation biplot.

The distribution of 27 T-, B-, and natural killer-cell subsets in the peripheral blood of 40 patients with multiple myeloma (MM), ten patients with monoclonal gammopathy of undetermined significance (MGUS), and 40 healthy donors was investigated by means of classical univariate statistics and advanced multivariate data-analytical techniques. The latter approach was used to describe, represent, and analyze lymphocyte subset distribution in a two-dimensional correlation biplot, allowing comparison of complex lymphocyte profiles (i.e., compound lymphocyte subset distributions) of individual subjects rather than isolated subset values of selected patient and/or donor groups. The correlation biplot revealed that, in accordance with the univariate statistics, the MM patients were characterized by marked shifts towards CD8+, CD57+, CD62L-, CD(16+56)+, and HLA-DR+ T cells, suggesting in vivo immune activation. The activation profile was most markedly observed in treated MM patients in the advanced disease stage category. The lymphocyte profiles of MGUS patients were heterogeneous, with approximately half of them located in the swarm of MM patients and the other half in the swarm of healthy donors. Although the univariate statistics revealed significant differences between MGUS patients and healthy donors only within the B-cell compartment, the correlation biplot revealed that two MGUS patients clearly had a typical T-cell activation profile similar to that of the MM patients. One MGUS patient with a T-cell activation profile progressed 13 months later to a stage IA MM and required chemotherapy. A marked lymphocyte profile shift in one MM patient was associated with terminal and aggressive disease transformation. Our study illustrates further the practical use of correlation biplots for the detection of aberrant lymphocyte profiles and/or profile shifts in individual patients.

Patients with high-risk myelodysplastic syndrome can have polyclonal or clonal haemopoiesis in complete haematological remission.

The clonality of mature peripheral blood-derived myeloid and lymphoid cells and bone marrow haemopoietic progenitors from 18 females with myelodysplasia (MDS) (five refractory anaemia, RA; one RA with ringed sideroblasts, RARS; three chronic myelomonocytic leukaemia, CMML; four RA with excess of blasts, RAEB; five RAEB in transformation, RAEB-t) was studied by X-chromosome inactivation analysis. Using the human androgen-receptor (HUMARA) assay, we analysed the clonal patterns of highly purified immature CD34+ 38- and committed CD34+ 38+ marrow-derived progenitors, and CD16+ 14- granulocytes, CD14+ monocytes, CD3+ T and CD19+ B lymphocytes from peripheral blood. In high-risk patients (RAEB, RAEB-t), clonality analysis was performed before and after intensive remission-induction treatment. All patients, except one with RA, had predominance of a single clone in their granulocytes and monocytes. The same clonal pattern was found in CD34+ progenitor cells. In contrast, CD3+ T lymphocytes were polyclonal or oligoclonal in 14/18 patients. X-chromosome inactivation patterns of CD19+ B cells were highly concordant with CD3+ T cells except for two patients (one RA, one CMML) with monoclonal B and polyclonal T lymphocytes, therefore suggesting a clonal mutation in a progenitor common to the myeloid and B-lymphoid lineages or the coexistence of MDS and a B-cell disorder in these particular patients. After high-dose non-myeloablative chemotherapy, polyclonal haemopoiesis was reinstalled in the mature myeloid cells and immature and committed marrow progenitors in three of four patients achieving complete haematological remission. Therefore we conclude that most haematological remissions in MDS are associated with restoration of polyclonal haemopoiesis.

Peripheral blood lymphocyte subset shifts in patients with untreated hematological tumors: evidence for systemic activation of the T cell compartment.

Flow cytometry immunophenotyping of peripheral blood lymphocyte subsets and multivariate data-analytical techniques revealed that among untreated hemato-oncological patients (n = 48) with lymphomas, acute and chronic myeloid and lymphocytic leukemias, monoclonal gammopathy of undetermined significance, and multiple myeloma, 42% had (nonmalignant) lymphocyte profiles clearly distinct from healthy donors. Notably, a similar pattern of increased CD3+ CD57+, CD3+ HLA-DR+, CD3+ CD(16 + 56)+, CD4- CD8+, CD8+ CD57+, CD8+ CD28-, and CD8+ CD62L- subsets was detected. More extensive three-color immunophenotyping on an additional group of 49 untreated patients revealed that both CD4+ and CD8+ T cells displayed significant increases of activation markers: CD69, CD(16 + 56), HLA-DR, CD71, and CD57, and a loss of CD62L and CD28, which is also interpreted as a sign of activation. Consistent with the phenotypical signs of in vivo immune activation, polyclonal cytolytic activity, measured ex vivo in an anti-CD3-redirected assay, was detected within immunomagnetically purified CD4+ T cells of three out of six B-CLL patients investigated, but not within purified CD4+ T cells of five healthy donors. The purified CD8+ T cells of patients (n = 28) and donors (n = 5) on the other hand displayed similar polyclonal cytotoxic activities at the various effector:target ratios investigated. Tumor-directed cytotoxic activity of purified CD4+ (n = 6) and/or CD8+ T cells (n = 15) against freshly isolated autologous tumor cells was not detected in any of the experiments. Collectively, our results demonstrate systemic T cell activation as a common feature in hematological neoplasia, and a markedly enhanced cytolytic activity of the CD4- subset in CLL patients. The reason(s) for this expansion of activated T cells and its pathophysiologic significance, however, remain unclear.

A single course of remission reinduction chemotherapy for acute myelogenous leukemia relapsing after allogeneic bone marrow transplantation is complicated by graft-versus-host disease and followed by sustained complete remission.

Graft-versus-host disease (GVHD) remains a major immunological complication after allogeneic bone marrow transplantation (allo-BMT), but also favors development of the beneficial graft-versus-leukemia (GVL) effect. A patient with AML-M4 (inv (16)) is described, who was given non-myeloablative remission reinduction therapy for leukemic relapse (inv (16), trisomy 8) diagnosed on day 184 after HLA-compatible sibling BMT. On day 236, ie about 6 weeks after completion of this course, a clinical syndrome suggestive of acute GVHD grade 3 had developed. Skin biopsy confirmed the clinical diagnosis of GVHD, with a compatible liver biopsy. Transfusion-associated GVHD was ruled out by analysis of short tandem repeat (STR) alleles in the skin biopsy, revealing alleles from donor and recipient but not from third party origin. Cyclosporin A (CsA) therapy, which had been tapered between days 150 and 175, was resumed, resulting in a favorable response and gradual transition to limited chronic GVHD. The patient has since remained in complete remission with an excellent performance status for more than 40 months, without further chemotherapy. Thus this biopsy proven case of GVHD was induced by marrow donor lymphocytes more than 200 days after transplantation and apparently triggered by remission reinduction chemotherapy. The case indicates that intensive non-myeloablative chemotherapy can cure AML relapsing after allo-BMT. The therapeutic effect in this case probably involved a direct pharmacological suppression of the leukemic clone followed by a GVL effect initiated by donor-derived alloreactive T lymphocytes.

Multivariate reconstruction of lymphocyte profiles in a two-dimensional graphical model as a tool for the investigation of lymphocyte subset distribution in health and disease.

Advanced multivariate data-analytical techniques are proposed to concisely represent and evaluate complex lymphocyte profiles (i.e., compound lymphocyte subset distributions) of individual subjects in easily interpretable, two-dimensional, graphical correlation biplots. The lymphocyte profile of each subject is represented by its location in the model, and the score of a subject for a particular lymphocyte subset is inferred from the perpendicular projection on a rotated axis that coincides with this lymphocyte subset. Simultaneously, the model yields information about the correlation between the lymphocyte subsets. Furthermore, individuals with aberrant lymphocyte profiles can be easily identified. In case studies of 80 healthy donors and of 40 patients with multiple myeloma, 10 patients with monoclonal gammopathy of undetermined significance, and 50 age- and sex-matched healthy donors, reconstruction of the two-dimensional lymphocyte profiles from 27 flow-cytometric characterized lymphocyte subsets succeeded in representing 43% and 51% of the total information (variability) contained within the 80 x 27 (= 2,160) and 100 x 27 (= 2,700) flow cytometry measurements, respectively. It is concluded from the present studies that the correlation biplot represents a unique and powerful tool to concisely describe, represent, and analyze complex lymphocyte profiles of individual subjects and the heterogeneity in lymphocyte profiles among these subjects.