Which Markers Should the used for Diagnostic Chronic Lymphocytic Leukemia Immunophenotyping Scoring System by Flow Cytometry?

BACKGROUND

The scoring system used for chronic lymphocytic leukemia (CLL) cannot make an accurate diagnosis in some cases. Novel markers are available for the differential diagnosis of CLL, especially from MCL. However, these markers are still not incorporated into diagnostic algorithms. We investigated the role of CD43, CD81, CD200, and ROR1 in the differential diagnosis of CLL and their expression in non-CLL cases.

METHODS

We investigated the role of CD43, CD81, CD20, and ROR1 in the differential diagnosis of CLL by incorporating them into the diagnostic panel after studying peripheral blood or bone marrow samples of 165 patients with 8-color flow cytometry.

RESULTS

CD43 positivity was a sensitive marker but had a lower specificity for CLL. CD43 had high diagnostic value for CLL (sensitivity 100%, specificity 88.5%, AUC 98.0%). CD200 was a specific marker for CLL (sensitivity 98%, specificity 90%, AUC: 96%). CD81 expression was highest in the MCL cases, with a median expression rate of 68.5% (range: 54 - 82.5%). It was negative in all the CLL cases. For CLL, CD81 negativity had a sensitivity of 95%, a specificity of 82% and an AUC of 92%. ROR1 was positive in all CLL and MCL cases. CD79b, on the other hand, was a fairly sensitive and specific marker for MCL.

CONCLUSIONS

CD43, CD81, CD200, and ROR1 should be incorporated into diagnostic algorithms for the differential diagnosis of CLL, especially from MCL.

Chronic Refractory Idiopathic Thrombocytopenic Purpura (ITP) and Anti-CD20 Monoclonal Antibody: A Case Report

Idiopathic thrombocytopenic purpura (ITP) is an immune-mediated disorder characterized by accelerated and premature destruction of platelets by reticuloendothelial system. CD20, a trans-membrane B-cell-specific antigen, is a potential target for treatment of certain malignant and nonmalignant plasma cell disorders including refractory ITP. Rituximab is a genetically engineered human anti-CD20 monoclonal antibody, which is approved for the treatment of low-grade non-Hodgkin’s lymphoma. Recent clinical reports suggest that rituximab may be useful in treating certain patients with chronic refractory ITP. A 59-year-old woman with refractory ITP was placed on rituximab (four weekly doses of 375 mg/m2) and her condition and platelet count were observed for 18 months. There was a gradual increase in platelet count and she was symptom free in this period and no side effects of the drug were reported. Anti-CD20 antibodies are likely to be used in the treatment of refractory ITP cases, but further studies about treatment schedule and criteria for patient selection should be done.

[The case of hairy cell leukosis in pediatrics]

According publications' data, hairy cell leukosis encounters in humans aged from 26 to 70 years and in males four times more often than in females. The disease is manifested by impotence, splenomegaly, and presence in blood and bone marrow clone of lymphoid cells with particular morphology, cytochemic markers and immune phenotype (sIg+, CD19+, CD20+, CD5-, CD10-, with marked expression of CD25+, CD103+). The presented clinical case of illness with hairy cell leucosis is the first one detected in pediatric practice in adolescent of 16 years old.

Pharmacokinetics and pharmacodynamics of ASKP1240, a fully human anti-CD40 antibody, in normal and renal transplanted Cynomolgus monkeys

BACKGROUND

The purpose of this study was to evaluate the serum concentration of ASKP1240 (pharmacokinetics [PK]) and the CD40 occupancy of ASKP1240 (pharmacodynamics [PD]) in normal and renal transplanted Cynomolgus monkeys to clarify the PK/PD relationship.

METHODS

In a 70-day study, two ASKP1240 doses (2 and 5 mg/kg) were evaluated in normal and transplanted monkeys. Full doses were administered during the induction phase, and half doses were administered during the maintenance phase. The PK and PD were assessed using ELISA and FACS assays.

RESULTS

The serum concentration and receptor occupancy of ASKP1240 reached their maximum levels rapidly after the first dose and remained at an almost saturated rate during the induction phase. They then decreased gradually during the maintenance phase in all of the groups. The serum concentration and duration of full receptor occupancy were dose dependent in the normal and transplanted monkeys. On day 70 after therapy with 5 mg/kg ASKP1240, the transplanted monkeys presented a significantly lower occupancy of the CD40 receptors compared with the normal animals (5.5%±14.1% vs. 72.8%±3.4%). The serum concentration of ASKP1240 was also strongly correlated with the occupancy of the ASKP1240 receptors.

CONCLUSION

This study showed strong positive PK/PD relationships in renal transplanted and normal monkeys. The results may thus serve as a guide for optimal dosage and timing of ASKP1240 therapy in clinical trials and will propel the translation of ASKP1240 therapeutics from the bench to preclinical and clinical trials.

Extramedullary hematopoietic pleural effusion accompanied by follicular lymphoma

Extramedullary hematopoietic effusion (EHE) is recognized to be an unusual phenomenon accompanied by hematologic disorders. Only a few reports are available of EHE occurring in patients with lymphoma. We herein report the case of a 54-year-old man with follicular lymphoma. Bone marrow aspirates and biopsied specimens showed diffuse invasion of small cleaved atypical lymphoid cells that were positive for CD10, 20, bcl2, immunoglobulin lambda and Bcl-2-IgH rearrangement. The pleural effusion aspirates and a biopsied specimen obtained via thoracoscopy revealed megakaryocytes and immature myeloid cells in addition to lymphoma cells. To the best of our knowledge, this is the first report of EHE accompanied by lymphoma according to the World Health Organization classification.

CD20-positive T-cell large granular lymphocyte leukemia: case report and review of the literature

CD20-positive T-cell malignancy is a rare disease. We report a case of CD20-positive T-cell large granular lymphocyte leukemia (T-LGLL). The leukemic cells were positive for CD20 and T cell markers, such as CD3, CD4, CD5, CD8 and CD57. A monoclonal rearrangement of the T-cell receptor (TCR) beta chain gene was detected. Twenty-three cases of well-documented CD20-positive T-cell malignancies were reviewed. Most cases were mature T-cell malignancies, especially exhibiting a cytotoxic T-cell phenotype, despite a diversity of the pathological diagnoses. Additional cases must be evaluated to clarify the implications of CD20 expression on T-cell malignancies and to elucidate whether such cases constitute a distinct biologic and clinical disease entity. The accumulation of cases will help to facilitate provision of a proper treatment for CD20-positive T-cell malignancies in the future.

[Galavit-induced change of immunologic parameters in patients with non-small lung cancer]

Administration of an immunomodulator, galavit, for stage II-III non-small lung cancer along with standard therapy was followed by immunological vigor improvement by the end of the course. CD3, CD4, IgA, IgM and IgG indices were normal in more than 80% of the study group by day 51 after surgery; CD8, CD20 and HLA-DR--in more than 50%; CD16--in 45.2%. In control, by day 51, normal IgG and HLA-DR levels were reported in 60%. The remaining indices were normal in less than 50%. Our results point to immunological vigor improvement due to use of galavit. The drug is well tolerated, has neither side effects nor toxicity.

Altered CD19/CD22 balance in Egyptian children and adolescents with systemic lupus erythematosus

B cells from systemic lupus erythematosus (SLE) patients display signalling defects that may underlie disease pathogenesis activity.CD19 and CD22 play a major role as regulators of B-cell response. The aim of this study was to clarify the relationship between B cell surface markers namely CD19, CD20 and CD22 expression and clinical and laboratory indices of SLE activity. The study included 33 SLE patients and 20 healthy children and adolescents as controls. Flowcytometric assay of dual markers, CD19/CD20, and CD20/CD22 was done. SLE disease activity was assessed by SLEDAI score. CD22% was significantly higher while CD20% was significantly lower in the study compared to the control group. No significant difference was observed in both groups with respect to CD19% or CD19/CD22% ratio. The level of CD22 expression was significantly lower in high and very high active cases than in mild and moderate cases and negatively correlated with SLDEAI score and ESR. Results obtained showed that, B cell surface receptors CD20 and CD22 are significantly affected in patients with SLE, pointing to their possible involvement in the aetiopathogenesis of the disease and in the regulatory mechanisms in response to the immune disturbance.

A 9-yr evaluation of carrier erythrocyte encapsulated adenosine deaminase (ADA) therapy in a patient with adult-type ADA deficiency

Adenosine deaminase (ADA) deficiency is an inherited disorder which leads to elevated cellular levels of deoxyadenosine triphosphate (dATP) and systemic accumulation of its precursor, 2-deoxyadenosine. These metabolites impair lymphocyte function, and inactivate S-adenosylhomocysteine hydrolase (SAHH) respectively, leading to severe immunodeficiency. Enzyme replacement therapy with polyethylene glycol-conjugated ADA is available, but its efficacy is reduced by anti-ADA neutralising antibody formation. We report here carrier erythrocyte encapsulated native ADA therapy in an adult-type ADA deficient patient. Encapsulated enzyme is protected from antigenic responses and therapeutic activities are sustained. ADA-loaded autologous carrier erythrocytes were prepared using a hypo-osmotic dialysis procedure. Over a 9-yr period 225 treatment cycles were administered at 2-3 weekly intervals. Therapeutic efficacy was determined by monitoring immunological and metabolic parameters. After 9 yr of therapy, erythrocyte dATP concentration ranged between 24 and 44 micromol/L (diagnosis, 234) and SAHH activity between 1.69 and 2.29 nmol/h/mg haemoglobin (diagnosis, 0.34). Erythrocyte ADA activities were above the reference range of 40-100 nmol/h/mg haemoglobin (0 at diagnosis). Initial increases in absolute lymphocyte counts were not sustained; however, despite subnormal circulating CD20(+) cell numbers, serum immunoglobulin levels were normal. The patient tolerated the treatment well. The frequency of respiratory problems was reduced and the decline in the forced expiratory volume in 1 s and vital capacity reduced compared with the 4 yr preceding carrier erythrocyte therapy. Carrier erythrocyte-ADA therapy in an adult patient with ADA deficiency was shown to be metabolically and clinically effective.

Development of a Mimotope-Based Vaccine Against CD20 Antigen

CD20, a B-cell-specific protein, is a primary target for immunotherapy of B-cell lymphomas. We used a mimotopes of CD20 to construct vaccines for B-cell-related disorders. The immunogenicity of the vaccines was tested in BALB/c mice. Results of this study suggest that the mimotope may be a useful tool for the construction of a functional vaccine to treat B cell-related disorders.

Efficacy of rituximab (anti-CD20) for refractory systemic lupus erythematosus involving the central nervous system

AIM

Neuropsychiatric systemic lupus erythematosus (NPSLE) is a serious treatment-resistant phenotype of systemic lupus erythematosus. A standard treatment for NPSLE is not available. This report describes the clinical and laboratory tests of 10 patients with NPSLE before and after rituximab treatment, including changes in lymphocyte phenotypes.

METHODS

Rituximab was administered at different doses in 10 patients with refractory NPSLE, despite intensive treatment.

RESULTS

Treatment with rituximab resulted in rapid improvement of central nervous system-related manifestations, particularly acute confusional state. Rituximab also improved cognitive dysfunction, psychosis and seizure, and reduced the SLE Disease Activity Index Score at day 28 in all 10 patients. These effects lasted for >1 year in five patients. Flow cytometric analysis showed that rituximab down regulated CD40 and CD80 on B cells and CD40L, CD69 and inducible costimulator on CD4+ T cells.

CONCLUSIONS

Rituximab rapidly improved refractory NPSLE, as evident by resolution of various clinical signs and symptoms and improvement of radiographic findings. The down regulation of functional molecules on B and T cells suggests that rituximab modulates the interaction of activated B and T cells through costimulatory molecules. These results warrant further analysis of rituximab as treatment for NPSLE.

Thrice-Weekly Low-Dose Rituximab Decreases CD20 Loss via Shaving and Promotes Enhanced Targeting in Chronic Lymphocytic Leukemia

Treatment of chronic lymphocytic leukemia (CLL) patients with standard dose infusion of rituximab (RTX), 375 mg/m2, induces clearance of malignant cells from peripheral blood after infusion of 30 mg of RTX. After completion of the full RTX infusion, substantial recrudescence of CLL cells occurs, and these cells have lost > 90% of CD20. To gain insight into mechanism(s) of CD20 loss, we investigated the hypothesis that thrice-weekly low-dose RTX (20 or 60 mg/m2) treatment for CLL over 4 wk would preserve CD20 and enhance leukemic cell clearance. During initial infusions in all 12 patients, the first 30 mg of RTX promoted clearance of > 75% leukemic cells. Four of six patients receiving 20 mg/m2 RTX retained > or = 50% CD20, and additional RTX infusions promoted further cell clearance. However, four of six patients receiving 60 mg/m2 had CD20 levels < 20% baseline 2 days after initial infusions, and additional RTX infusions were less effective, presumably due to epitope loss. Our results suggest that when a threshold RTX dose is exceeded, recrudesced RTX-opsonized cells are not cleared, due to saturation of the mononuclear phagocytic system, but instead are shaved of RTX-CD20 complexes by acceptor cells. Thrice-weekly low-dose RTX may promote enhanced clearance of circulating CLL cells by preserving CD20.

Outcomes in patients with splenic marginal zone lymphoma and marginal zone lymphoma treated with rituximab with or without chemotherapy or chemotherapy alone

BACKGROUND

The optimal management of patients with splenic marginal zone lymphoma/marginal zone lymphoma (SMZL) is controversial. The objective of this retrospective study was to compare the outcomes of patients with SMZL who received treatment with rituximab, rituximab plus chemotherapy, or chemotherapy alone.

METHODS

The Leukemia Service database was searched for patients with splenic lymphoma who were registered between May 1995 and October 2004. The indications for treatment were the same as those used for patients with chronic lymphocytic leukemia.

RESULTS

SMZL was confirmed in 70 patients. The median age was 64 years. The median number of CD20 molecules per cell was 69 x 10(3). Forty-three patients required systemic therapy; rituximab in 26 patients, chemotherapy plus rituximab in 6 patients, and chemotherapy alone in 11 patients. Ten additional patients underwent splenectomy, and 17 patients were in the observation group. The overall response rates were 88% with rituximab, 83% with rituximab plus chemotherapy, and 55% with chemotherapy alone; the 3-year survival rates were 95%, 100%, and 55%, respectively. The 3-year failure-free survival (FFS) rates were 86%, 100%, and 45% in the rituximab, rituximab plus chemotherapy, and chemotherapy alone groups, respectively. Rituximab treatments resulted in longer survival and FFS compared with chemotherapy. Rituximab alone resulted in disappearance of splenomegaly in 92% of patients and normalization of absolute lymphocyte counts. In univariate analysis, younger age and rituximab-based therapy were predictive of longer FFS.

CONCLUSIONS

Rituximab with or without chemotherapy was found to have major activity in patients with SMZL. These results may be associated with high levels of cellular CD20 antigen sites. Rituximab should be the treatment of choice, at least in older patients with SMZL who have comorbid diseases.

A phase II trial of rituximab as adjuvant to intensive sequential chemotherapy in patients under 60 years with untreated poor-prognosis diffuse large B-cell lymphoma

The potential benefit of rituximab as adjuvant to high-dose therapy (HDT) has been investigated in patients under 60 years with poor-risk (age-adjusted international prognostic index at 2-3) CD20+ diffuse large B-cell lymphoma (DLBCL). The treatment consisted of four cycles of high-dose CEOP (cyclophosphamide, epirubicin, vincristine, prednisone), plus etoposide and cisplatin during the two last cycles. Peripheral blood stem cells were collected after cycle 1, and reinfused after cycles 3 and 4. Four weekly rituximab infusions were subsequently delivered. Among the 36 patients included, 30 could complete chemotherapy schedule, and 24/36 received rituximab. A complete response occured in 26/36 patients (72%). With a median follow-up of 30 months, the estimated 5-year overall survival (OS) and event-free survival (EFS) rates (mean +/- s.d.) were 65 +/- 16 and 63 +/- 15%, respectively. For the 24 patients who received both chemotherapy and rituximab, the estimated 5-year OS and EFS rates were 86 +/- 14 and 82 +/- 15%. These data suggest that rituximab after HDT is feasible. Both complete remission rate and survival curves compare favorably with the poor outcome usually observed in high-risk DLBCL patients managed with HDT without rituximab.

ABO-Incompatible Kidney Transplantation and Rituximab

We have designed a protocol for ABO-incompatible kidney transplantations based on antigen-specific immunoadsorption rather than plasmapheresis to remove anti-A or anti-B antibodies and with a Prograf/Cellcept/prednisolone protocol using rituximab rather than splenectomy to prevent rebound antibodies. Twelve patients have successfully received transplants with this protocol. The ABO-antibodies were readily removed by the antigen-specific immunoadsorption and maintained at a low-level posttransplantation. There were no side effects. All patients have normal renal transplant function with a follow-up of 1 to 34 months.

Failure of rituximab in human immunodeficiency virus-associated multicentric Castleman disease

Two human immunodeficiency virus-infected patients who needed etoposide therapy to control exacerbations of Castleman disease received four infusions of rituximab. Clinical and virologic relapses with increased blood human herpesvirus-8 DNA levels occurred in both patients 4 and 24 weeks later and were associated with a worsening of Kaposi sarcoma.

CD20-negative large-cell lymphoma with plasmablastic features: a clinically heterogenous spectrum in both HIV-positive and -negative patients

BACKGROUND

Plasmablastic lymphoma (PBL) has been described as a rapidly progressive and almost invariably fatal CD20- VS38c+ diffuse large-cell lymphoma with plasmablastic features, almost exclusively involving the jaw and oral mucosa in HIV-positive patients.

METHODS

From 2001 to 2003 we evaluated 12 men with PBL, and report the pathology, clinical findings, treatment and outcome. Six of 12 were HIV-positive while among the others, one was post-renal transplant, one had ulcerative colitis and four had no known immunodeficiency.

RESULTS

Tumor growth pattern, in general, showed cohesiveness and a starry-sky pattern; the morphology varied from typical plasmablastic to centroblastic cells. Partial immunophenotypes were (+/total): CD138, 11 of 12 (91.7%); MIB1 10 of 11 (4+, range 75-95%); p63/VS38c, nine of 10 (90%); EBV, eight of 11 (73%); LCA(CD45), two of 12 (16.7%); HHV8/LANA, zero of 10; ALK, zero of seven; and CD20, zero of 12. Three had stage IE and nine stage IV disease. Nine of 12 had an intermediate/high International Prognostic Index or high-risk disease. Computed tomography and positron emission tomography scan in four of 12 revealed extensive bone metastases. Eight of 12 are alive after treatment, with a median follow-up of 11+ months (range 1-24). Of the HIV-positive patients, five of six are alive with a median follow-up of 17 months.

CONCLUSIONS

It appears that PBL are heterogenous in terms of clinical presentation and morphology. The outcome presented here is superior to that originally reported.

Assessing immunoglobulin heavy chain rearrangements in pediatric CD20-positive and CD20-negative classic Hodgkin's disease

Approximately 15% of all cases of childhood classical Hodgkin's disease (HD) express CD20, a B-cell marker associated with immunoglobulin heavy chain rearrangements. Immunoglobulin heavy chain rearrangements in Reed-Sternberg cells could be used to assess minimal residual disease (MRD), as was shown with immunoglobulin heavy chain patient-specific primers (PSPs) in non-Hodgkin's lymphoma. The aim of this study was to analyze pediatric HD for future design of immunoglobulin heavy chain PSP for MRD detection. DNA was extracted from paraffin-embedded tissue from unstained slides of 8 pediatric CD20+ nodular sclerosis HD cases and 10 CD20-nodular sclerosis HD cases. Immunoglobulin heavy chain polymerase chain reaction and sequencing were performed on 16 of 18 cases, which had adequate DNA for further analysis. Sequence analysis from 3 cases (19% of HD cases) demonstrated unique V(D)J regions, which could potentially be used to design PSP. Unique PSPs could be used to assess MRD in advanced-stage HD specimens. Future studies should focus on improved detection and analysis of more cases to identify appropriate specimens in assessing clinical implications of MRD detection.

Importance of Cellular Microenvironment and Circulatory Dynamics in B Cell Immunotherapy

B cell immunotherapy has emerged as a mainstay in the treatment of lymphomas and autoimmune diseases. Although the microenvironment has recently been demonstrated to play critical roles in B cell homeostasis, its contribution to immunotherapy is unknown. To analyze the in vivo factors that regulate mechanisms involved in B cell immunotherapy, we used a murine model for human CD20 (hCD20) expression in which treatment of hCD20(+) mice with anti-hCD20 mAbs mimics B cell depletion observed in humans. We demonstrate in this study that factors derived from the microenvironment, including signals from the B cell-activating factor belonging to the TNF family/BLyS survival factor, integrin-regulated homeostasis, and circulatory dynamics of B cells define distinct in vivo mechanism(s) and sensitivities of cells in anti-hCD20 mAb-directed therapies. These findings provide new insights into the mechanisms of immunotherapy and define new opportunities in the treatment of cancers and autoimmune diseases.

[Characteristics and clinical significance of immunophenotype in chronic lymphocytic leukemia]

OBJECTIVE

To investigate the characteristics of immunophenotype of chronic lymphocytic leukemia (CLL) and to evaluate the prognosis of CLL by using the indexs of the characteristics of immunophenotype combined with serum LDH and beta2-MG levels.

METHODS

The immunophenotype of 15 CLL, 12 AML, 11 ALL, and 1 FCL (follicular cell lymphoma) patients were analyzed by the indirect immunofluorescent assay. The serum LDH and beta2-MG were detected in 13 CLL patients by the rate nephelometry.

RESULTS

The mean age of episode for CLL was 62.9 years and the ratio of male to female was 4:1 in the CLL group. The immune markers (CD5, CD19, and CD20) were positive in the 15 CLL, and negative in the 11 ALL and the 12 AML. The expression of CD23 was positive in 12 of the 15 CLL and negative in the 11 ALL and 12 AML. The expression of CD38 was positive in the 15 CLL. The immunophenotype of 1 FCL was CD10+, CD19+, CD20+, CD5- and CD23-. The serum beta2-MG and LDH levels in 9 CLL patients at Stage Binet C were significantly higher than those in 3 CLL patients at Stage Binet A (P < 0.05).

CONCLUSION

CD19+, CD20+ and CD5+ are specific assembly of immunophenotype in B-CLL and contribute to the diagnosis of CLL. The clinical stage of CLL patients of CD23- belongs to Stage Binet C, indicating the poor prognosis. CD23 contributes to differentiate CLL from FCL. CD38+ as a prognostic marker of CLL is not specific. The levels of LDH and beta2-MG are useful indexes for evaluating the prognosis of CLL.

[Guideline for radioimmunotherapy of rituximab relapsed or refractory CD20(+) follicular B-cell non-Hodgkin's lymphoma]

This guideline is a prerequisite for the quality management in the treatment of non-Hodgkin-lymphomas using radioimmunotherapy. It is based on an interdisciplinary consensus and contains background information and definitions as well as specified indications and detailed contraindications of treatment. Essential topics are the requirements for institutions performing the therapy. For instance, presence of an expert for medical physics, intense cooperation with all colleagues committed to treatment of lymphomas, and a certificate of instruction in radiochemical labelling and quality control are required. Furthermore, it is specified which patient data have to be available prior to performance of therapy and how the treatment has to be carried out technically. Here, quality control and documentation of labelling are of greatest importance. After treatment, clinical quality control is mandatory (work-up of therapy data and follow-up of patients). Essential elements of follow-up are specified in detail. The complete treatment inclusive after-care has to be realised in close cooperation with those colleagues (haematology-oncology) who propose, in general, radioimmunotherapy under consideration of the development of the disease.

Delayed hepatitis B virus reactivation after cessation of preemptive lamivudine in lymphoma patients treated with rituximab plus CHOP

Preemptive lamivudine in lymphoma patients undergoing intensive chemotherapy can effectively prevent chemotherapy-related HBV reactivation. Nevertheless, the safety profile after withdrawal of lamivudine and the impact of rituximab-containing chemotherapy on HBV reactivation has not been defined. To illustrate the necessity of prolonged surveillance after cessation of preemptive lamivudine in lymphoma patients treated with rituximab and chemotherapy, four patients with B-cell NHL carrying HBV received rituximab plus CHOP. Preemptive lamivudine therapy was administered 1 week before chemotherapy until 4 weeks after completion of chemotherapy. Serial serum alanine aminotransferase (ALT), total bilirubin, and HBV-DNA levels were prospectively monitored in three patients. The fourth patient was closely monitored for ALT. The HBV DNA was checked after development of clinical overt hepatitis. The peripheral blood CD20+ B-lymphocyte counts were analyzed periodically in two patients. All of the three patients studied prospectively had virological relapses with surgence of HBV DNA 6-8 months after completion of rituximab-plus-CHOP (R+CHOP) therapy. Two of the three patients had biochemical relapses and one of them developed severe hepatitis. Sequencing for HBV polymerase gene in these patients failed to show evident emergence of lamivudine-resistant mutations. The fourth patient developed a hepatitis flare-up 6 months after completion of chemotherapy. The CD2+ lymphocytes were totally depleted when HBV DNA started to increase. Delayed HBV reactivation can occur in lymphoma patients receiving R+CHOP after withdrawal of preemptive lamivudine. More protracted lamivudine therapy may be an alternative to close monitoring following chemotherapy, and further studies are needed to define optimal duration of lamivudine therapy.

Rituximab infusion promotes rapid complement depletion and acute CD20 loss in chronic lymphocytic leukemia

Complement plays an important role in the immunotherapeutic action of the anti-CD20 mAb rituximab, and therefore we investigated whether complement might be the limiting factor in rituximab therapy. Our in vitro studies indicate that at high cell densities, binding of rituximab to human CD20(+) cells leads to loss of complement activity and consumption of component C2. Infusion of rituximab in chronic lymphocytic leukemia patients also depletes complement; sera of treated patients have reduced capacity to C3b opsonize and kill CD20(+) cells unless supplemented with normal serum or component C2. Initiation of rituximab infusion in chronic lymphocytic leukemia patients leads to rapid clearance of CD20(+) cells. However, substantial numbers of B cells, with significantly reduced levels of CD20, return to the bloodstream immediately after rituximab infusion. In addition, a mAb specific for the Fc region of rituximab does not bind to these recirculating cells, suggesting that the rituximab-opsonized cells were temporarily sequestered by the mononuclear phagocytic system, and then released back into the circulation after the rituximab-CD20 complexes were removed by phagocytic cells. Western blots provide additional evidence for this escape mechanism that appears to occur as a consequence of CD20 loss. Treatment paradigms to prevent this escape, such as use of engineered or alternative anti-CD20 mAbs, may allow for more effective immunotherapy of chronic lymphocytic leukemia.

Successful anti-CD20 monoclonal antibody treatment of severe autoimmune hemolytic anemia due to warm reactive IgM autoantibody in a child with common variable immunodeficiency

Autoimmune hemolytic anemia due to warm reactive IgM autoantibodies is unusual, severe, and often fails to respond to standard immunosuppressive therapies in both adults and children. A 6-year-old girl with common variable immunodeficiency had longstanding steroid dependent, splenectomy-unresponsive, warm IgM autoantibody-mediated autoimmune hemolytic anemia. Rituximab, a monoclonal antibody directed against CD20 antigen, was used to deplete B lymphocytes and reduce autoantibody production. She received a total of six doses of rituximab (375 mg/m2). Therapy was well tolerated, and B-lymphocytes were effectively depleted from the peripheral blood. The patient was completely tapered off glucocorticoids. The patient has remained off immunosuppressive agents for 16 months despite the return of B lymphocytes to the peripheral circulation. She continues to require IVIG. Early treatment with rituximab might be an option for patients with warm reactive IgM autoantibody-mediated autoimmune hemolytic anemia not responding to other treatments or experiencing untoward side effects from those treatments.

Circulating CD20 and CD52 in patients with non-Hodgkin's lymphoma or Hodgkin's disease

The cell surface proteins CD20 and CD52 differ significantly in their structures and are expressed on the majority of B cells. Both circulating CD20 (cCD20) and circulating CD52 (cCD52) have been recently documented in patients with chronic lymphocytic leukaemia. A retrospective study to establish whether cCD20 and/or cCD52 were detectable in patients with lymphoma, and the clinical associations of these soluble antigens if detected, was conducted. cCD20 and cCD52 levels were analysed in a cohort of 65 patients with non-Hodgkin's lymphoma (NHL) and 37 with Hodgkin's disease (HD). Patients with NHL had elevated pretherapy levels of cCD20 and cCD52 compared with normal individuals. Patients with HD had significantly lower than normal pretherapy levels of both cCD20 and cCD52. cCD20 levels were marginally elevated post-therapy in NHL patients while in patients with HD, cCD20 levels remained significantly lower than normal after therapy. Serum cCD52 levels became significantly lower than normal post-therapy in NHL patients, and remained significantly lower than normal in HD patients. No predictive effects were found for pretherapy or post-therapy levels of cCD52 on survival for either cohort of patients. Post-therapy cCD20 levels independently highly correlated with survival in patients with NHL. Prospective evaluation will be required to establish if cCD20 and cCD52 may be used as biomarkers in the diagnosis, prognostic categorization, and monitoring of the clinical course in patients with lymphoma. The clinical significance of circulating antigen in patients receiving monoclonal antibody therapy directed against CD20 and/or CD52 warrants study.

B-Cell lymphoproliferative syndrome and peripheral blood CD20+ cells expansion after hematopoietic stem cell transplantation: association with fludarabine and anti-thymocyte globulin containing conditioning regimen

Fifty-eight patients who received hematopoietic stem cell transplants during a 3-year period in our unit were followed for the symptoms of posttransplant B-cell lymphoproliferative syndrome (B-cell PTLD). Three cases showed lymph node enlargement; in 14, there was an excess of B cells in the blood. Histochemical staining of lymph nodes revealed CD20+ cell expansion in two cases, and in one, CD38+ and CD138+ cells. Kappa and lambda staining revealed poly- or oligoclonal expansion, which was characterized by the presence of Ki67+ cells in 10% to 50% of cells. In 14 cases, an excess of CD20+ cells were observed in blood. Clinical analysis revealed that patients with B-cell expansion in blood and/or in lymph nodes frequently showed fever and that some subjects displayed arthralgia, hemolytic anemia, and hepatitis. LMP-1-positive cells were observed in lymph nodes as well as EBV copies, whereas only a proportion of patients with the excessive CD20+ cells in blood were EBV positive. Notably, lymph node enlargement and CD20+ blood excess occurred significantly more frequently among patients receiving a Fludarabine (Flu) and anti-thymocyte globulin (ATG) conditioning regimen than those whose treatment lacked Flu independent of whether they received ATG (0.80 vs 0.44; P =.036).

Tumor origin and CD20 expression in posttransplant lymphoproliferative disorder occurring in solid organ transplant recipients: implications for immune-based therapy.1

BACKGROUND

Posttransplant lymphoproliferative disorder (PTLD) is a potentially fatal complication of transplantation for which new therapies are being explored, including cytotoxic T-cell infusion and anti-CD20 antibody. Whether the PTLD is of donor cell or recipient cell origin influences the type of cytotoxic T-cell therapy, in view of the MHC-restricted nature of the immune response. The efficacy of anti-CD20 therapy, on the other hand, depends on CD20 expression by neoplastic cells. Only limited prior data exist regarding either of these parameters.

METHODS

Materials for this study were obtained in part from a Southwest Oncology Group clinical trial of solid organ transplant patients with PTLD. Tumor tissue from 21 patients (15 heart, 4 lung, and 2 kidney recipients) was evaluated for donor versus recipient origin by analyzing DNA at multiple polymorphic microsatellites.

RESULTS

Twenty tumors (95%) were of recipient origin. Anatomically separate tumors from a given patient had the same origin. A single PTLD of donor origin arose in donor lung. Epstein-Barr virus (EBV), as assessed by EBER and LMP1 histochemical stains, was present in 16 of 17 tumors. CD20, evaluated immunohistochemically, was expressed diffusely in 12 of 17 tumors and focally in 3 and was undetectable in 2 tumors.

CONCLUSIONS

PTLD after solid organ transplantation is frequently EBV-related and of recipient origin, implying that therapeutic EBV-specific T cells must be matched to the HLA type of the recipient, not that of the donor, in most cases of PTLD. Variable CD20 expression among tumors suggests that in some patients anti-CD20 therapy might be more effective in combination with other therapies.

Update on leucodepletion, HLA and platelet serology at Lisbon Regional Blood Centre

The characteristic performance of some leucodepletion processes at the Lisbon Regional Blood Centre is presented. The current position on HLA and platelet serology is briefly described.

Circulating CD20 is detectable in the plasma of patients with chronic lymphocytic leukemia and is of prognostic significance

CD20 is a 33- to 36-kDa transmembrane phosphoprotein involved in the activation, proliferation, and differentiation of B lymphocytes. The predicted amino acid sequence of the CD20 suggests 4 transmembrane-spanning regions with both N- and C-termini located in the cytoplasm. We demonstrate herein that significant levels of circulating CD20 (cCD20) can be detected in the plasma of patients with chronic lymphocytic leukemia (CLL) and that cCD20 interferes with the binding of rituximab, a humanized anti-CD20 monoclonal antibody, to CLL cells. An enzyme-linked immunosorbent assay (ELISA) was developed to measure circulating cCD20 levels in the plasma. We measured cCD20 levels in the plasma of 180 patients with CLL and correlated these levels with clinical characteristics and outcome. Circulating CD20 levels correlated positively with beta(2)-microglobulin level (p =.006) and percentage of CD38(+) cells (p =.03) and negatively with platelet count (p =.004) and hemoglobin level (p =.02). Patients with advanced Rai (III/IV) or Binet (C) stage disease had significantly higher levels of cCD20 than did patients with earlier-stage disease (P =.01 and P =.006, respectively). There was no correlation between cCD20 level and age, lymphocyte count, or white blood cell count. Using a recursive classification method, we found that patients with a cCD20 level more than 1875 nM/L had significantly shorter survival than those with cCD20 1875 nM/L or below (P =.01). The prognostic value of cCD20 was independent of Rai staging or hemoglobin level. Prospective evaluation is indicated to establish whether rituximab dosing should be adjusted according to cCD20 levels.

CD3-negative, CD20-positive T-cell prolymphocytic leukemia: case report and review of the literature

We report a case of CD3-negative, CD20-positive T-cell prolymphocytic leukemia (T-PLL). The leukemic cells were of medium-to-large size, mature-looking, and did not have cytoplasmic granules. The leukemic cells were negative for surface CD3, CD2, and CD7 and strongly positive for CD20. T-cell lineage markers such as CD4, CD5, and cytoplasmic CD3 were also positive. A monoclonal rearrangement of the T-cell receptor (TCR) beta chain gene was detected. CD3-negative T-PLL has been reported often, but CD20-positive T-PLL has not. We reviewed seven cases of CD20-positive immature and mature T-cell leukemias, including the present case. Three were immature T-cell leukemias (acute lymphoblastic leukemia), and four were mature T-cell leukemias (granular lymphocytic leukemia, small lymphocytic lymphoma/chronic lymphocytic leukemia, adult T-cell leukemia, and the present case). Splenomegaly was a common feature. However, our case alone had "bright" CD20 expression on the leukemic cells. This is the first report of CD20(+) T-PLL.

Effect of blood sample handling and reverse transcriptase-polymerase chain reaction assay sensitivity on detection of CK20 expression in healthy donor blood

Data concerning the specificity of cytokeratin 20 (CK20) as a reverse transcriptase-polymerase chain reaction analysis (RT-PCR) marker to detect disseminated tumor cells in blood are conflicting. Underlying causes for these discrepancies need to be determined to clarify the significance of CK20 detection. Because differences in RT-PCR assays and blood sample handling may be important, their influence on CK20 detection was studied. Using a series of healthy donor blood samples spiked with colon tumor cells, the authors compared the sensitivities of two conventional PCRs with different primer sets and a quantitative LightCycler PCR (Roche Diagnostics GmbH, Penzberg, Germany). Additionally, the influence of sample collection and preparation on assay specificity was studied by examining CK20 expression in the mononuclear cell fraction (MNC) of the first and the second aliquot of blood drawn from healthy donors and in the granulocyte cell fraction. At the concentration of one spiked tumor cell/mL blood, the CK20 detection frequency varied from 17% and 67% for the conventional to 78% for the LightCycler PCR. In the unspiked samples, CK20 was detected in 0% and 8% of the conventional and in 11% of the LightCycler PCR tests. Quantitative analysis revealed that CK20 was expressed at a high level in the granulocyte samples. The results demonstrate that differences in assay sensitivity and sample handling influence CK20 detection in blood.

Autologous peripheral blood stem cell transplantation and anti-B-cell directed immunotherapy for refractory auto-immune haemolytic anaemia

We report the clinical course of a 6.5-year-old boy with refractory auto-immune haemolytic anaemia. Due to failure of conventional immunosuppressive therapy, an autologous peripheral blood stem cell transplantation was performed. The conditioning regimen consisted of cyclophosphamide and anti-thymocyte globulin. The patient was reinfused with 2.6 x 10(6) CD34 positive selected, B- and T-cell-depleted peripheral blood stem cells per kg body weight. He showed a partial response with a reduced demand for red blood cell transfusions. However, due to persistence of the haemolytic process he was started on rituximab therapy on day +40 post-transplant. Following two doses of rituximab, the patient improved rapidly and developed a sustained complete response. After 10 months, haemolysis recurred and responded again to rituximab therapy without the necessity for red blood cell transfusions. 15 months after initial antibody treatment, however, the patient developed a second relapse which was now refractory to rituximab therapy although CD20+ B-lymphocytes were cleared from the peripheral blood.

CONCLUSION

Our case report suggests that rituximab and autologous peripheral blood stem cell transplantation are important though not curative elements in the treatment of patients with severe auto-immune haemolytic anaemia who are refractory to conventional immunosuppressive therapy.

CD-20 expression in post-transplant lymphoproliferative disorders: treatment with rituximab

B-cell lymphoproliferative disorders are rare but serious complications of solid organ and bone marrow transplantation. We report that these tumors frequently express the CD-20 antigen, and immunotherapy directed at this antigen may be a well-tolerated and effective treatment.

Prospective 5-year study of peripheral blood CD4, CD8, and CD19/CD20 lymphocytes and serum Igs in children born to HIV-1 women. The P(2)C(2) HIV Study Group

BACKGROUND

Peripheral blood CD4(+) and CD8(+) T cells, CD19(+)/20(+) B cells, and serum Igs are known to be altered by the progression of pediatric HIV-1 infection, but their evaluation as predictors of survival needs further definition.

OBJECTIVE

To determine the natural history of these immune factors and their importance in predicting survival, we studied 298 HIV-1 vertically infected (HIV-1(+)) children over a 5-year period.

METHODS

These immune factors and serum HIV-1 RNA levels were measured in two groups: (1) a birth cohort of children enrolled up to age 28 days postnatally, including 93 HIV-1(+) and 463 HIV-1 uninfected infants (HIV-1(-)), and (2) an older cohort of 205 HIV-1(+) children enrolled after the age of 28 days, who were classified as survivors or nonsurvivors.

RESULTS

In the birth cohort HIV-1(+) children had significantly lower CD4(+) T-cell counts, higher CD8(+) T-cell counts, and lower CD19(+)/20(+) B-cell counts and higher IgG, IgA, and IgM levels than HIV-1(-) children. In the older cohort survivors had significantly higher CD4(+) and CD8(+) T-cell and CD19(+)/CD20(+) B-cell counts and higher IgG, lower IgA, and lower IgM levels than did nonsurvivors. In univariable analysis factors affecting survival in the older cohort were baseline CD4(+) and CD8(+) T-cell and CD19(+)/20(+) B-cell counts and IgG and HIV-1 RNA levels (all P <.05). In multivariable analysis high baseline CD4(+) T-cell count and low baseline HIV-1 RNA load remained important.

CONCLUSION

The longitudinal mean profiles of CD4 and CD8 T-cell and CD19/20 B-cell counts and serum IgG levels helped to describe the natural progression of HIV-1 disease in children. However, only baseline CD4 T-cell count independently predicted survival.

Effect of interferon-alpha on CD20 antigen expression of B-cell chronic lymphocytic leukemia

Chimeric CD20 monoclonal antibody as alternative therapy in relapsed low-grade non-Hodgkin's lymphoma (NHL) has produced responses in nearly 50% of patients. Augmenting CD20 expression on tumor cells and/or inducing its expression may increase the cell kill and effectiveness of antibody therapy. Peripheral blood lymphocytes from 19 patients with B-cell chronic lymphocytic leukemia (B-CLL) were incubated in vitro in the presence of interferon-alpha (IFN-alpha) (500 U/ml and 1,000 U/ml) for 24 and 72 hours. The effect on CD20 expression was studied by flow cytometry. The differences in the percentage positivity, the mean fluorescence intensity (MFI), and the product of percentage positivity and MFI were used to assess upregulation. There was a significant upregulation of CD20 expression on B cells seen at both concentrations after 24-hour priming (p < 0.01). B-CLL cells cultured for 72 hours in the presence of IFN-alpha also showed upregulation of CD20 expression; however, the degree of upregulation was much lower than that seen at 24 hours. There was no statistically significant increase in CD20 antigen expression on normal lymphocytes following cytokine exposure. These results suggest that IFN-alpha priming may augment the effectiveness of antibody therapy by directly upregulating CD20 antigen expression in addition to its indirect action through effector cells of the host.

Interferon-gamma therapy reduces blood leukocyte levels in patients with atopic dermatitis: correlation with clinical improvement

Atopic dermatitis (AD) is a chronic inflammatory skin disease with abnormalities of both cellular and humoral immunity. Subcutaneous recombinant human interferon-gamma (IFN-gamma) provides therapeutic benefit to AD patients. In contrast to expectations, IFN-gamma does not cause a decrease in the elevated levels of circulating IgE levels in AD patients. We sought to determine cellular targets of IFN-gamma treatment that might explain its clinical benefit. Therefore, we evaluated blood leukocyte subsets by multiparameter flow cytometry in AD patients receiving IFN-gamma (n = 10) or placebo (n = 11) therapy compared to untreated normal volunteers (n = 14). Treated patients demonstrated reductions in WBC, eosinophil, and lymphocyte counts. Compared to normals, there was a reduced CD4/CD8 ratio in AD patients among activated, large mononuclear cells that was partially corrected with IFN-gamma treatment. Clinical improvement correlated with reductions in WBC (r = 0.9, P = 0.0003), eosinophil (r = 0.7, P = 0.035) and lymphocyte (r = 0.8, P = 0.013) counts, and with normalization of the CD4/CD8 ratio among large lymphocytes (r = 0.9, P = 0.04). The data indicate two potential modes of action for INF-gamma in AD. One mechanism represents normalization of selected immunologic abnormalities in AD; a second mechanism may be the modest reduction of circulating inflammatory cells. Adequacy of IFN-gamma therapy of AD may depend on bringing about these changes.

Analysis of circulating tumor cells in patients with multiple myeloma during the course of high-dose therapy with peripheral blood stem cell transplantation

In multiple myeloma (MM) circulating CD19+ cells have been considered as myeloma precursors. As these cells are also possibly a reservoir of treatment resistant disease evaluation of the CD19+ cells during the course of high-dose therapy has to be a major concern. We determined the number of tumor cells in the CD19+ as well as CD19- fractions of PB of eight patients with disease sensitive to VA[I]D chemotherapy, of 10 patients who achieved partial or complete remission post-high-dose therapy (HDT) with peripheral blood stem cell transplantation (PBSCT) and of a further seven patients with disease progression post-transplantation. CD19+ cell fractions were obtained by preparative sequential magnetic and fluorescence activated cell sorting with a median purity of 97.1%. In addition, PB samples of seven patients post-transplantation were sorted for CD20+ cells (median purity, 98.7%). The number of tumor cells in the CD19+, the CD19- and the CD20+ fractions were determined using a quantitative CDR3 PCR assay. The number of CD19+ tumor cells in patients in remission post-HDT was similar to those of the patients post-VA[I]D (median, 1.05 vs 0.92 CD19+ tumor cells/ml PB, P = 0.72) providing evidence for the persistence of this tumor cell fraction during the course of HDT. This was in contrast to the CD19- compartment, in which the number of tumor cells was significantly reduced in those patients in remission post-transplantation (median, 53 vs 0 CD19- tumor cells/ml PB; P = 0.006). In patients with progressive disease the number of tumor cells in both cell fractions was significantly higher (CD19+: median, 1.05 vs 21 tumor cells/ml PB, P = 0.05; CD19-: 0 vs 63 tumor cells/ml PB, P = 0.008). While the absolute number of CD19+ cells was reduced in the group of patients after VA[I]D treatment, a polyclonal CD19+ reconstitution had occurred in patients responding to HDT. The tumor cell content in the CD19+ fractions could be confirmed by the results obtained analyzing the CD20+ cell fractions. In conclusion, these results indicate that disease progression after PBSCT in MM is accompanied by an expansion of tumor cells in both the CD19+ and CD19- fractions. Similar numbers of CD19+ clonotypic cells post-HDT suggest that these cells persist and thus, contribute to disease dissemination and relapse.

A receptor for the lipocalin placental protein 14 on human monocytes

Human placental protein 14 (PP14), a member of the lipocalin structural superfamily, is an abundant amniotic fluid glycoprotein with documented immunoinhibitory activities. While receptors have been characterized for several other lipocalins, none have been reported to date for PP14. In the present study, two-color immunofluorescence and flow cytometry was used to screen peripheral blood mononuclear cell subpopulations for their capacity to engage fluoresceinated recombinant PP14. The tagged PP14 bound strongly in a specific and saturable fashion to CD14+ (monocyte lineage) cells, but not to CD20+ (B cell lineage) or CD3+ (T cell lineage) cells. This binding was both pH- and temperature-sensitive, and was reduced by proteolytic pre-digestion of the cells with trypsin or proteinase K. Scatchard analysis demonstrated a single class of receptors on CD14+ cells, with a K(D) of approximately 1 x 10(-8) and approximately 10-35,000 receptors per cell. These findings constitute the first report of a cell surface-associated binding protein for PP14 and set the stage for exploring the molecular mechanisms of PP14-mediated signaling and immunomodulation.

CD20 is a molecular target for scFvFc:zeta receptor redirected T cells: implications for cellular immunotherapy of CD20+ malignancy

The CD20 molecule was evaluated as a B-cell lymphoma target epitope for T cells expressing a CD20-specific single-chain FvFc-zeta (scFvFc:zeta) chimeric receptor. A cDNA construct consisting of a murine kappa leader sequence, CD20-specific scFv, human immunoglobulin (Ig) G1 hinge-C(H)2-C(H)3, the human CD4 transmembrane, and the intracellular signaling domain of the human CD3 complex's zeta chain was synthesized by polymerase chain reaction splice-overlap extension. The human CD4+ Jurkat cell line was electroporated with the CD20-specific scFvFc:zeta construct cloned into the mammalian expression vector pcDNAneo. Western blot analysis of transfectant whole cell lysate with an anti-zeta antibody demonstrated the expression of both endogenous zeta and the chimeric receptor protein, with a mobility consistent with the expected molecular weight of 66 kD under reducing conditions; nonreduced lysate revealed a chimeric receptor complex of approximately 132 kD. The scFvFc:zeta receptor was present on the cell surface as detected by flow cytometry of T-cell transfectants stained with an anti-mouse Fab-specific antibody and anti-human Fc gamma-specific monoclonal antibody. Coculture of Jurkat transfectants with CD20+ lymphoma cells resulted in the accumulation of interleukin (IL)-2 in culture supernatants as detected by ELISA. IL-2 production was triggered by the specific interaction between the CD20 molecule and the scFvFc:zeta as IL-2 was not detected in cultures with mock transfected Jurkat cells or CD20- stimulator cells. Furthermore, IL-2 production was inhibited by the addition of a soluble anti-CD20 monoclonal antibody to cocultured Jurkat transfectants and CD20+ stimulator cells. The capacity of CD20 to trigger the lytic machinery of scFvFc:zeta-expressing cytotoxic T lymphocytes (CTLs) was assessed using the murine allo-specific CD8+ CTL clone 2c. CD20-specific redirected cytolytic activity against human lymphoma targets was observed with 2c transfectants in a 4-hour chromium release assay. These results demonstrate that CD20 can serve as a target epitope for scFvFc:zeta receptor-expressing T cells.

Age-related changes in major lymphocyte subsets in cynomolgus monkeys

Age-related changes in major lymphocyte subsets were analyzed in 195 cynomolgus monkeys (Macaca fascicularis) aged from one month to 31 years. The percentages of CD20+ B cells in peripheral blood lymphocytes (PBL) decreased with age to five years of age, but after that, no significant change was observed. The percentages of CD16+ NK cells gradually increased during the first five years and reached the peak at from four to ten years of age, whereas the percentages of CD3+ T cells in PBL were relatively constant throughout the life. Among the T cells, the CD4+ CD8- T cells decreased, but CD4- CD8+ T cells increased within the first decade of life. We further analyzed the expressions of CD28 and CD29 molecules on T cells to determine the relation between age-related activation and phenotypic changes. Almost all CD4+ CD8- T cells (> 90%) were CD28+ at all ages analyzed, but a clear age-related decrease in CD28 expression was demonstrated in CD4- CD8+ T cells during the first ten years. In the case of CD29 expression, age-related increases in CD29hi cells were apparent in both CD4+ CD8- and CD4- CD8+ T cells during the first ten years. The percentages of CD29hi cells, however, were higher in CD4- CD8+ T cells than in CD4+ CD8- T cells in all ages analyzed. These results indicated that the age-related changes in percentages of major lymphocyte subsets as well as in phenotypes of T cells might be related to the maturation of the immune system including an increase in memory cells in cynomolgus monkeys.

Levels of expression of CD19 and CD20 in chronic B cell leukaemias

AIMS

To investigate whether the antigen levels of the B cell lineage markers CD19 and CD20 can distinguish between normal and neoplastic B cells or characterise distinct expression patterns among the chronic B cell leukaemias.

METHODS

Peripheral blood cells from 70 patients with B cell disorders and 17 healthy donors were analysed by quantitative flow cytometry. Direct immunofluorescence staining was performed with phycoerythrin conjugated CD19 and CD20 monoclonal antibodies. Standard microbeads with different capacities to bind mouse immunoglobulins were used to convert the mean fluorescence intensity (MFI) values into number of antigen molecules/cell, expressed as antibody binding capacity (ABC).

RESULTS

CD19 and CD20 ABC values in leukaemic B cells differed from those of normal blood B lymphocytes. The results identified distinct profiles of CD19 and CD20 expression in the various types of B cell leukaemias. In all leukaemias studied except hairy cell leukaemia (HCL), CD19 expression was significantly lower than the mean (SD) value in normal B cells (22 (7) x 10(3) molecules/cell), as follows: chronic lymphocytic leukaemia (CLL), 13 (7) x 10(3); B prolymphocytic leukaemia (B-PLL), 16 (9) x 10(3); splenic lymphoma with villous lymphocytes (SLVL), 15 (11) x 10(3); mantle cell lymphoma (MCL), 10 (7) x 10(3). In HCL there was strong CD19 expression (38 (16) x 10(3)). In contrast, the level of expression of membrane CD20 was higher than the mean (SD) value in normal B cells (94 (16) x 10(3) molecules/cell) in MCL (123 (51) x 10(3)); B-PLL (129 (47) x 10(3)); SLVL (167 (72) x 10(3)); and HCL (312 (110) x 10(3)); while it was significantly lower (65 (11) x 10(3)) in CLL compared with normal B cells and the other B cell leukaemias.

CONCLUSIONS

Quantitative determination of CD19 and CD20 may provide useful diagnostic information for the study of B lymphoproliferative disorders.

Comparative study on age-dependent development of surface receptors on peripheral blood lymphocytes in children and young nonhuman primates (marmosets)

General conformity was found concerning age-dependent changes in the major subsets (CD4, CD8, CD2, CD20) and the adhesion molecules CD11a and CD29 on peripheral blood lymphocytes in children and young marmosets (Callithrix jacchus). Differences exist in the expression of the surface receptors CD45RA and CD56. Taking the total number of white blood cells into account, an age-related increase in the absolute numbers of peripheral blood lymphocytes was found in marmosets whereas in children, an age-dependent decrease was observed. The definition of reference ranges for different stages of maturation in children and young marmosets may serve as a basis on which comparative risk assessment of possible effects on lymphocyte subsets after pre- or perinatal drug exposure can be estimated.

Leukocyte trafficking in free-flowing cerebrospinal fluid of normal rhesus macaques (Macaca mulatta)

Cellular components in free-flowing cerebrospinal fluid (CSF) of normal rhesus macaques were characterized. Microscopic counting enumerated the total number of leukocytes, percentage of polymorphonuclear cells (PMN), leukocytes with nonspecific esterase (NSE), and those reducing nitro blue tetrazolium (NBT). Flow cytometric analysis further identified CD4, CD8, CD14, and CD20 positive leukocytes. These experiments established reliable techniques for evaluating cellular components in CSF from rhesus macaques and documented the difference in the CD4/CD8 ratio between peripheral blood (PB) and CSF compartments under normal physiological conditions.

Circulating CD20dim T-lymphocytes increase with age: evidence for a memory cytotoxic phenotype

The CD20 antigen has been regarded as a B lineage specific, 35 kDa, non-glycosylated membrane phosphoprotein, which functions as either a Ca2+ ion channel or as a regulatory protein of such a channel. Weak expression of CD20 (CD20dim), however, has recently been reported on a sub-population of T lymphocytes. We present results which confirm the existence of a CD20dim T lymphocyte population and show that such cells have a reduced antibody-binding capacity, when compared to CD20bright B-cells (10337 +/- 642 and 346311 +/- 24264 respectively). In addition, CD20dim cell counts vary with age, with the highest levels occurring in octogenarians: cord blood 0.3 +/- 0.1% (n = 13), 20-60 year-old group 2.1 +/- 1.1% (n = 18) and individuals > or = 61 years of age 6.9 +/- 3.2% (n = 10) (P < 0.001). Further characterization of CD20dim T cells, using three colour flow cytometry, demonstrated a predominantly memory cytotoxic phenotype, in that the cells were CD8+CD28+CD45RO+T-CR alpha beta +CD38-HLA-DR-.