Subsequent chemotherapy regimens are well tolerated after radioimmunotherapy with yttrium-90 ibritumomab tiuxetan for non-Hodgkin's lymphoma

PURPOSE

Yttrium-90 (90Y) ibritumomab tiuxetan (Zevalin; IDEC Pharmaceutical, San Diego, CA) is an effective therapy for patients with relapsed B-cell non-Hodgkin's lymphoma. The predominant toxicity of 90Y ibritumomab tiuxetan has been myelosuppression, and concern has been expressed about the tolerability of further treatment after this therapy. The goal of this analysis was to evaluate the therapy given to patients who relapsed after 90Y ibritumomab tiuxetan.

PATIENTS AND METHODS

A retrospective analysis was performed on 58 patients treated at a single institution on five separate protocols that used 90Y ibritumomab tiuxetan 0.4 mCi/kg. All patients had experienced disease progression after 90Y ibritumomab tiuxetan treatment and received subsequent therapy. The toxicity seen in this cohort of patients with subsequent treatment regimens was analyzed and compared with that of control groups who did not receive 90Y ibritumomab tiuxetan.

RESULTS

The median number of subsequent therapies was two (range, one to seven). Sixteen (28%) of the 58 patients received growth factor support with subsequent chemotherapy, and two patients were treated with reduced doses because of persistent pancytopenia. Eight patients subsequently had an autologous stem-cell transplantation with stem cells collected after 90Y ibritumomab tiuxetan therapy. Excluding patients hospitalized at the time of transplantation, 13 patients were hospitalized for neutropenic fever, thrombocytopenia, or both. When compared to patients who did not receive 90Y ibritumomab tiuxetan, there was no significant difference in toxicity.

CONCLUSION

We conclude that chemotherapy or autologous stem-cell transplantation after prior therapy with 90Y ibritumomab tiuxetan is feasible and reasonably well tolerated. The toxicity with subsequent therapy seems similar to that in patients not treated with 90Y ibritumomab tiuxetan.

Primary follicular lymphoma of the testis in childhood: an entity with peculiar clinical and molecular characteristics

BACKGROUND/AIMS

Paediatric primary follicular lymphoma of the testis (PPFLT) is exceptional: the few reported cases seem to lack BCL-2 gene rearrangement and/or protein expression. The aim of this study was to characterise a PPFLT arising in a 4 year old boy.

METHODS

This case was characterised using conventional histological analysis, immunohistochemistry, and a polymerase chain reaction based method for the detection of immunoglobulin V(H) chain rearrangements.

RESULTS

The neoplasm was staged I(E)/A; left orchiectomy and chemotherapy were performed, producing complete remission. Histology showed a predominantly follicular lymphoid infiltrate mainly composed of centroblast-like cells. The phenotype was CD20(+), CD79a(+), CD10(+), bcl-6(+), B cell specific activating protein(+), kappa light chain(+), CD30(-/+), interferon regulating factor 4(-/+), c-myc(-/+), lambda light chain(-), CD3(-), bcl-2(-), p53(-), cytokeratin(-), and placental alkaline phosphatase(-). Lymphomatous elements were found within a CD21(+) follicular dendritic cell network and 70% were positive for Ki-67/MIB-1. Molecular analysis revealed monoclonal immunoglobulin heavy chain gene rearrangement and BCL-6 mutations, in the absence of BCL-2 major breakpoint and BCL-2 minor cluster region rearrangements, p53 mutations, and death associated protein kinase gene hypermethylation.

CONCLUSIONS

These findings suggest a different pathogenesis of PPTFL compared with adult follicular lymphoma and might explain its favourable course in spite of aggressive histology.

Progress and promise in the treatment of indolent lymphomas

In the era of conventional alkylating agent-based chemotherapy, advanced stage indolent lymphoma has been considered incurable. The failure of our traditional therapies to cure these patients, coupled with the indolent course of the disease and the elderly population affected, has fostered a nihilistic attitude about the treatment of these diseases. Twenty years ago, in the absence of interesting alternatives to alkylating agents, judicious use and reuse of alkylators was perhaps the best we could do. There are now many reasons for optimism and excitement in the treatment of these diseases, including the availability of promising agents such as interferon-alpha, the nucleoside analogues, and rituximab. Radioimmunotherapy will also likely play a role in future therapy programs. Allogeneic stem cell transplantation is a high-risk approach that is not an option for all patients, but it has the potential to cure patients, even in the setting of relapse. Mini-allogeneic transplantation may permit an approach to allogeneic transplantation that is better tolerated than standard transplant strategies. In addition to these therapy options, biological insights have provided new options for monitoring patients. Molecular monitoring (polymerase chain reaction for bcl-2) is a stringent measure of short-term treatment efficacy, and one that correlates with durability of remission, i.e., it is a surrogate marker by which to judge treatment efficacy. There used to be a limited number of conventional treatment approaches, which consistently failed. The pendulum has swung. There are now many promising new options. It is time to plan and conduct trials that are geared for success.

Combination immunotherapy with rituximab and interleukin 2 in patients with relapsed or refractory follicular non-Hodgkin's lymphoma

Rituximab has significant activity as a single agent in the treatment of follicular non-Hodgkin's lymphoma (NHL). Interleukin 2 (IL-2) is a lymphokine that increases effector cell number. In an effort to augment antibody-dependent cell-mediated cytotoxicity (ADCC) associated with rituximab therapy, low-dose IL-2 was added to a standard rituximab regimen and patients were evaluated for safety and efficacy. Twenty patients with relapsed or refractory follicular NHL were treated with IL-2 (1.2 MIU/m(2)/d for 56 d subcutaneously) as outpatients. Rituximab (375 mg/m(2)) was given on d 15, 22, 29 and 36. The regimen was well tolerated and only three patients required dose adjustments in IL-2. Infusional toxicity associated with rituximab was not exacerbated by IL-2. Peripheral blood immunophenotyping demonstrated significant increases in circulating CD8+ and CD56+ lymphocytes in all evaluable patients (P = 0.0002). Increases in total eosinophil number were observed in all patients. Eleven patients responded to therapy, for an overall response rate of 55%. Four additional patients had stable disease. For these 15 patients, the median time to progression exceeded 13 months. We conclude concomitant cytokine therapy to enhance ADCC with monoclonal antibody therapy was well tolerated and did not exacerbate antibody-related infusional toxicity. Further studies of this rational combination are warranted and ongoing.

Clonal heterogeneity assessed by flow cytometry in B-cell lymphomas arising from germinal centers

Patients with mature follicular B-cell lymphomas develop aggressive non-Hodgkin lymphomas (NHLs) during disease progression. It is controversial whether most diffuse large B-cell lymphomas (DLBCLs) and Burkitt lymphomas (BLs) emerge as de novo lymphomas or from an original follicular lymphoma. To distinguish clonally related populations in aggressive NHL, we studied the immunophenotypic features of 18 consecutive samples from 16 patients. Three flow cytometric patterns were distinguished: (1) a homogeneous neoplastic population of large B cells with phenotypic features of follicular center cells; (2) 2 atypical populations of B cells, small monoclonal B cells, and large B cells with loss of some surface antigens; and (3) 2 clonal populations of small and large B cells sharing the same light-chain isotype. The 3 flow cytometric patterns were observed, respectively, in de novo DLBCL and BL, transformation into BL, and transformation into DLBCL. Flow cytometric data can provide valuable information about the natural history of NHL.

Randomized controlled trial of yttrium-90-labeled ibritumomab tiuxetan radioimmunotherapy versus rituximab immunotherapy for patients with relapsed or refractory low-grade, follicular, or transformed B-cell non-Hodgkin's lymphoma

PURPOSE

Radioimmunotherapy combines biologic and radiolytic mechanisms to target and destroy tumor cells, thus offering a needed therapeutic alternative for refractory non-Hodgkin's lymphoma (NHL) patients. This phase III randomized study compares the novel radioimmunotherapy yttrium-90 ((90)Y) ibritumomab tiuxetan with a control immunotherapy, rituximab, in 143 patients with relapsed or refractory low-grade, follicular, or transformed CD20(+) transformed NHL.

PATIENTS AND METHODS

Patients received either a single intravenous (IV) dose of (90)Y ibritumomab tiuxetan 0.4 mCi/kg (n = 73) or rituximab 375 mg/m(2) IV weekly for four doses (n = 70). The radioimmunotherapy group was pretreated with two rituximab doses (250 mg/m(2)) to improve biodistribution and one dose of indium-111 ibritumomab tiuxetan for imaging and dosimetry. The primary end point, overall response rate (ORR), was assessed by an independent, blinded, lymphoma expert panel.

RESULTS

ORR was 80% for the (90)Y ibritumomab tiuxetan group versus 56% for the rituximab group (P =.002). Complete response (CR) rates were 30% and 16% in the (90)Y ibritumomab tiuxetan and rituximab groups, respectively (P =.04). An additional 4% achieved an unconfirmed CR in each group. Kaplan-Meier estimated median duration of response was 14.2 months in the (90)Y ibritumomab tiuxetan group versus 12.1 months in the control group (P =.6), and time to progression was 11.2 versus 10.1 months (P =.173) in all patients. Durable responses of > or = 6 months were 64% versus 47% (P =.030). Reversible myelosuppression was the primary toxicity noted with (90)Y ibritumomab tiuxetan.

CONCLUSION

Radioimmunotherapy with (90)Y ibritumomab tiuxetan is well tolerated and produces statistically and clinically significant higher ORR and CR compared with rituximab alone.

The usefulness of immunohistochemistry in the diagnosis of follicular lymphoma in bone marrow biopsy specimens

We used a panel of paraffin antibodies to determine whether neoplastic and nonneoplastic lymphoid aggregates in the bone marrow can be distinguished reliably. Formalin-fixed, paraffin-embedded bone marrow core biopsy specimens with lymphoid aggregates were stained using primary antibodies directed against bcl-2, bcl-6, CD5, CD10, CD20, and CD23. We studied 61 cases (26 follicular lymphoma and 35 benign or atypical aggregates). We found that no single stain is sufficient for identification of neoplastic lymphoid aggregates. However, this distinction was made possible by using a panel of antibodies. Under the conditions we tested, the most useful antibodies were CD10, bcl-2, CD5, and CD20. Most benign or atypical aggregates do not express CD10 and CD23. In addition, nonneoplastic aggregates had a large population of T cells. bcl-2 was useful in an architectural context for distinguishing neoplastic aggregates. bcl-6 often was expressed in both neoplastic and nonneoplastic aggregates and, thus, poorly discriminated between these processes. We studied the expression of CD10 and bcl-6 in selected lymph nodes in some cases.

Acquisition of potential N-glycosylation sites in the immunoglobulin variable region by somatic mutation is a distinctive feature of follicular lymphoma

Most patients with follicular lymphoma (FL) have somatically mutated V genes with intraclonal variation, consistent with location in the germinal center site. Using our own and published sequences, we have investigated the frequency of potential N-glycosylation sites introduced into functional V(H) genes as a consequence of somatic mutation. FL cells were compared with normal memory B cells or plasma cells matched for similar levels of mutation. Strikingly, novel sites were detected in 55 of 70 (79%) patients with FL, compared to 7 of 75 (9%) in the normal B-cell population (P <.001). Diffuse large B-cell lymphoma (DLCL) showed an intermediate frequency (13 of 32 [41%] patients). Myeloma and the mutated subset of chronic lymphocytic leukemia showed frequencies similar to those of normal cells in 5 of 64 (8%) patients and 5 of 40 (13%) patients, respectively. In 3 of 3 random patients with FL, immunoglobulin was expressed as recombinant single-chain Fv in Pichia pastoris, and glycosylation was demonstrated. These findings indicate that N-glycosylation of the variable region may be common in FL and in a subset of DLCL. Most novel sites are located in the complementarity-determining regions. V(H) sequences of nonfunctional V(H) genes contained few sites, arguing for positive selection in FL. One possibility is that the added carbohydrate in the variable region contributes to interaction with elements in the germinal center environment. This common feature of FL may be critical for tumor behavior.

Tumor cell dissemination in follicular lymphoma

The derivation of follicular lymphomas (FLs) from germinal centers is not only supported by their morphologic appearance with a nodular growth pattern and a germinal center-like cellular composition, but also by the presence of ongoing somatic hypermutation (a germinal center B cell-specific process) during their clonal expansion. The intraclonal sequence diversity of the tumor cells and their follicular growth pattern allows one to analyze lymphoma cell dissemination and the way the tumor "metastasizes" to distinct follicles. In the present study, we analyzed individual follicles of 3 FLs by micromanipulation of single cells from individual lymphoma follicles and amplification of immunoglobulin V region genes. Genealogical trees for the V(H) and the V(L) gene rearrangements were constructed to analyze the clonal relationship among individual cells of 3 distinct follicles of each case. In all 3 cases there is evidence that distinct tumor follicles are founded by many tumor cells, suggesting that there is extensive migration of the tumor cells among follicles. The observation that the tumor cells of FLs retain their follicular growth patterns despite this cellular migration supports the idea that they depend on the follicular microenvironment for their clonal expansion.

Primary cutaneous follicular lymphoma: an assessment of clinical, histopathologic, immunophenotypic, and molecular features

PURPOSE

Unlike nodal follicular lymphoma (NFL), Primary cutaneous follicular lymphomas (PCFLs) rarely express Bcl-2 protein or t(14;18)(q32;q21) (Bcl-2/IgH). The aim of this study was to further characterize PCFL in a large series from North America.

PATIENTS AND METHODS

Clinical data and archival formalin-fixed, paraffin-embedded tissue were obtained from 32 patients. PCFL was defined as follicular lymphoma limited to the skin at the time of diagnosis and within the first 6 months after diagnosis. Specimens were analyzed for the expression of CD3, CD10, CD20, Bcl-2, and Bcl-6 proteins by immunohistochemistry as well as for the presence of t(14;18)(q32;q21) by polymerase chain reaction.

RESULTS

The male-to-female ratio was 1.5:1, with a median age of 60 years. Twenty-four patients had lesions on the head and neck, five had lesions on the trunk, and three had lesions on both head and trunk. Follow-up data were available in all cases, with a mean length of 35.8 months. The majority of the patients were treated with radiation therapy. All patients were alive at last follow-up except one. Recurrence was noted in seven patients (22%), after a mean disease-free survival time of 17.7 months. CD10 and Bcl-6 expression were seen in 29 (91%) of 32 and 31 (97%) of 32 cases, respectively. Bcl-2 expression was noted in 13 (41%) of 32 cases. PCR results for t(14;18)(q32;q21) were positive in 11 (34%) of 32 patients and showed correlation with Bcl-2 protein expression. The sequencing of the t(14;18)(q32;q21) amplicons confirmed unique breakpoints in each of the seven tested cases. Comparison between the Bcl-2 and/or t(14;18)(q32;q21)-positive and t(14;18)(q32;q21)-negative cases revealed no significant difference in age, site, clinical course, or outcome.

CONCLUSION

We demonstrated Bcl-2 protein expression and t(14;18)(q32;q21) in a significant minority of cases, suggesting a relationship with NFL. It remains to be seen whether, on longer follow-up, there is any clinical difference in cases with and without t(14;18)(q32;q21).

Immunochemical studies of antigenic lymphoma-associated proteins

We have previously reported that plasma from patients with anaplastic lymphoma kinase (ALK)-positive lymphoma contains antibodies against the oncogenic kinase NPM-ALK protein characteristic of this disease. We investigated whether this reactivity represents a phenomenon unique to ALK-positive lymphoma by screening plasma from patients with follicular lymphoma for antibodies to BCL-2 protein. Eight out of 10 samples showed such reactivity (and in six cases gave specific staining of BCL-2-transfected cells). As these findings suggest a new biochemical approach to the identification of oncogenic proteins in lymphoma, we investigated whether antibodies present in patients with ALK-positive lymphoma can precipitate NPM-ALK in quantities which should be sufficient for further analysis. We found that plasma samples from all10 patients studied immunoprecipitated NPM-ALK asaprotein visible in silver-stained sodium dodecyl sulphatepolyacrylamide gels. Finally we demonstrated that NPM-ALK could be visualized more clearly if it were immunoprecipitated from extracts of cells in which newly synthesized proteins had been labelled with 35S and then identified by autoradiography. These results suggest a strategy for using patients' autoantibodies to screen for antibodies to other tumour-associated proteins.

T-cell analysis in identical twins reveals an impaired anti-follicular lymphoma immune response in the patient but not in the healthy twin

In lymphomas an innate defect in the T-cell repertoire could account for the impaired tumour-specific immune response; alternatively, the tumour itself could exert an inhibitory effect on the immune system. To address this issue we analysed the T-cell responses against follicular lymphoma (FL) in identical twins as it can be postulated that their overall T-cell repertoire is identical. While differences between the T-cell response of the patient and the healthy twin would point to a tumour-induced T-cell unresponsiveness, impaired responses in both would point to a defective T-cell repertoire. We demonstrated an impaired tumour-specific proliferation (P = 0.035 and P = 0.013) and cytokine release (P = 0.004 and P = 0.0008) of both peripheral blood and tumour-derived T-cells, respectively, in the FL patient compared with the T-cell response of the healthy twin. Moreover, only syngeneic primed T cells were able to directly lyse unmodified FL cells of the patient. These data support previous findings in murine lymphomas and suggest that inhibitory mechanisms during tumour growth, rather than a defective T-cell repertoire, are responsible for the insufficient T-cell response in lymphoma.

MCP-1 modulates chemotaxis by follicular lymphoma cells

The localization and establishment of follicular lymphoma (FL) cells in distinct anatomic sites probably involves chemokine and adhesion receptors on the neoplastic cells and appropriate chemokines and adhesion receptor ligands in the microenvironment. Several chemokines play an important role in normal B-cell trafficking and differentiation. Monocyte chemoattractant protein-1 (MCP-1) is a C-C chemokine that induces chemotaxis of a variety of lymphoid cells through its receptor CCR2. CCR2 is also expressed on B cells, and MCP-1 induces chemotaxis of normal B cells. In this report, we investigated expression and function of CCR2 on FL cells. We found FL cells as well as the t(14; 18)+ B-cell lymphoma line H2 expressed CCR2. MCP-1 potentiated SDF-1-induced chemotaxis of FL cells and H2 cells, but MCP-1 alone did not induce chemotaxis. The specificity of the effects of MCP-1 and SDF-1 was demonstrated by antibody blocking studies. Because FL cells are generally associated with follicular dendritic cells (FDCs), FDCs may be an important source of chemokines. We found that cultured FDCs produced MCP-1, and this production was enhanced by tumour necrosis factor. These data implicate MCP-1 in the migration and localization of FL cells.

Primary cutaneous follicle center cell lymphomas and large B cell lymphomas of the leg descend from germinal center cells. A single cell polymerase chain reaction analysis

Primary cutaneous B cell lymphomas are defined as non-Hodgkin lymphomas that occur in the skin without extracutaneous involvement for 6 mo after diagnosis. They are characterized by a less aggressive course and better prognosis than their nodal counterparts. According to the European Organization for Research and Treatment of Cancer classification, the major subentities of primary cutaneous B cell lymphoma are follicle center cell lymphomas, immunocytomas, and large B cell lymphomas of the leg, which differ considerably regarding their clinical behavior, the former two being indolent, the latter being of intermediate malignancy. In this study, we applied a single cell polymerase chain reaction approach to analyze immunoglobulin V(H)/V(L) genes in 532 individual B lymphocytes from histologic sections of four follicle center cell lymphomas localized on the head and trunk, and four large B cell lymphomas on the leg. We found: (i) in six of eight patients a clonal heavy chain, and in seven of eight patients a clonal light chain rearrangement, all being potentially productive; (ii) no bias in VH gene usage, in four of seven light chain rearrangements the V kappa germline gene IGVK3-20*1 was used; (iii) no biallelic rearrangements; (iv) all V(H)/V(L) genes are extensively mutated (mutation rate 5.4-16.3%); (v) intraclonal diversity in six of eight cases (three of each group); and (vi) low replacement vs silent mutation ratios in framework regions indicating preservation of antigen-receptor structure, as in normal B cells selected for antibody expression. Our data indicate a germinal center cell origin of primary cutaneous follicle center cell lymphomas and large B cell lymphomas independent of those belonging to one of these subentities.

Follicular lymphoma of the salivary gland: a clinicopathological and molecular study of six cases

To clarify the clinicopathologic, immunohistologic, and genotypic features of follicular lymphoma arising from the salivary glands, we examined 20 cases of operatively resected primary salivary gland lymphoma and identified 6 such cases. There were 4 women and 2 men with ages ranging from 38 to 64 years (median 50 years). The tumor arose from the parotid gland in 4 cases and the submandibular gland in the remaining 2. Four patients were stage IE and 2 were stage IIE-1. The median follow-up period was 49 months and all patients were alive and well at the time of going to press. Histologically, 5 patients were follicular lymphoma grade 2, and 1 was grade 3. In all specimens in noninfiltrating salivary gland tissue, there was periductal lymphocytic infiltration near the lymphoma. Moreover, myoepithelial sialoadenitis was noted in 2 lesions. An immunohistochemical study revealed all 6 cases were CD10+, CD79a+, bcl-6+, CD3-, CD5-, CD21-, CD23-, and CyclinD1-. The tumor cells expressed bcl-2 in 3 cases and p53 oncoprotein in 4 cases. Two cases revealed clonal bands with polymerase chain reaction (PCR) assay for the immunoglobulin heavy (IgH) gene. The bcl-2/IgH translocation at the major breakpoint region was detected in 1 case (16%). We found a relatively high incidence of follicular lymphomas (30%) in salivary gland lymphomas. Among the mucosa-associated lymphoid tissue (MALT) system, follicular lymphomas appeared to occur frequently in the salivary glands as well as the duodenum and skin. Moreover, follicular lymphoma arising from the salivary glands appeared to have some of the characteristics of MALT-type lymphoma including indolent prognosis, presence of myoepithelial sialoadenitis, and rarity of the BCL-2 gene rearrangement.

Rituximab therapy of patients with B-cell chronic lymphocytic leukemia

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

Expression of complement inhibitors CD46, CD55, and CD59 on tumor cells does not predict clinical outcome after rituximab treatment in follicular non-Hodgkin lymphoma

Rituximab is a chimeric monoclonal antibody that targets B-cell-specific antigen CD20 and an effective treatment for B-cell non-Hodgkin lymphoma. Although it is readily used in clinical practice, the exact mechanism of its antitumor effect is unclear. One potential mechanism involves complement-mediated cytotoxicity. It has been shown that rituximab induces complement-mediated cytotoxicity in follicular lymphoma cells in vitro, and complement inhibitors CD55 and CD59 may regulate this process. To determine whether complement inhibitors play a role in regulating the antitumor effect of rituximab, the expression of complement inhibitors CD46, CD55, and CD59 was analyzed in pretreatment tumor cells from 29 rituximab-treated follicular lymphoma patients. Among them, 8 patients achieved complete responses, 11 patients achieved partial responses, and 10 patients showed no or minimal responses to rituximab treatment. Expression of surface CD20, CD46, CD55, and CD59 was determined by 2-color flow cytometry. Although the CD59 level was slightly lower in the complete response group, there was no statistically significant difference in the expression of individual complement inhibitor CD46 (mean channel fluorescence [MCF]: NR, 26.4; PR, 21.9; CR, 29.9), CD55 (MCF: NR, 16.4; PR, 14.9; CR, 23.2), or CD59 (MCF: NR, 41.6; PR, 40.6; CR, 30.6), the combination of any 2 inhibitors, or all 3 on tumor cells from 3 response groups. In addition, there was no difference in the rituximab-induced complement-mediated cytotoxicity in an in vitro assay using tumor cells from 3 response groups. Thus, CD46, CD55, and CD59 expression on pretreatment tumor cells, or their susceptibility to in vitro complement-mediated killing, does not predict clinical outcome after rituximab treatment.

Higher levels of surface CD20 expression on circulating lymphocytes compared with bone marrow and lymph nodes in B-cell chronic lymphocytic leukemia

Differential expression of CD20 surface antigen in B-cell neoplasms at different sites is largely unknown. The number of CD20 antibodies bound per cell (CD20 ABC) in bone marrow (BM), peripheral blood (PB), and lymph node aspirate (LNA) samples from patients with B-cell chronic lymphocytic leukemia (B-CLL) or other B-cell disease was studied using quantitative flow cytometry. CD20 ABC differed significantly with the specimen type in B-CLL, being highest in PB (mean, 9,051) and lower in BM (mean, 4,067) and LNA (mean, 3,951). No difference in CD20 ABC between BM and PB samples was found in splenic lymphoma, mantle cell lymphoma, or follicular lymphoma. Also, we found a significant difference of CD20 ABC by type of disease: lowest in B-CLL; higher in splenic, follicular, and mantle cell lymphoma; and highest in hairy cell leukemia. The lower CD20 surface antigen levels in BM and LNA than in PB in B-CLL may have clinical relevance with regard to the efficacy of rituximab therapy.

CD30 expression in follicular lymphoma

CONTEXT

CD30(+) anaplastic large cell lymphomas were originally described as being of T-cell, null cell, and B-cell origin. CD30, however, is not a specific marker of anaplastic large cell lymphoma and has been found to be expressed in reactive as well as neoplastic populations as a probable activation marker. In addition, CD30(+) cells have also been described in both diffuse large B-cell and follicular lymphomas (FLs), resembling the pattern seen in reactive tonsils and lymph nodes.

OBJECTIVE

We report an index case of FL with CD30 expression, which on initial touch preparations and flow cytometric immunophenotyping revealed a prominent population of CD30(+) cells with marked cellular pleomorphism (anaplasia) in a background of typical FL. Immunohistochemistry of the paraffin section for CD30 in our index case confirmed unequivocal CD30(+) pleomorphic cells in the malignant nodules in occasional clusters. This case prompted a study of additional cases of FL for pattern of immunoreactivity with CD30 on paraffin sections.

DESIGN

Twenty-two additional cases of FL (grades 1-3) were retrieved for CD30 immunoperoxidase staining as in the index case.

RESULTS

This study demonstrated 32% of the additional cases of FL had definitive CD30(+), large, pleomorphic malignant cells by paraffin immunohistochemistry. In 2 cases (9%), the pattern of immunoreactivity with CD30 showed clustering and variable staining of large cells, as our index case.

CONCLUSION

This study underscores the morphologic and immunophenotypic spectrum of FL that includes CD30 staining and cellular pleomorphism.