Expression of the Leu-8 antigen by B-cell lymphomas

The Leu-8 antigen is found on the surface of many hematologic cells, including many T- and B-lymphocytes. With the use of a frozen-section immunoperoxidase technic, 152 B-cell non-Hodgkin's lymphomas were examined for Leu-8 expression. Of these lymphomas, 53% expressed Leu-8. Subclassification of the lymphomas with the use of the International Working Formulation showed that most small lymphocytic, intermediate lymphocytic, and diffuse large cell lymphomas and about half of diffuse small cleaved, diffuse mixed, and follicular lymphomas expressed Leu-8. In contrast, all 17 cases of small noncleaved cell (Burkitt's) lymphoma and 9 of 10 cases of multiple myeloma/plasmacytoma were Leu-8 negative. These results indicate that Leu-8 is expressed on a wide variety of B-cell lymphomas and that differences in Leu-8 expression may be useful in the diagnostic separation of small lymphocytic lymphoma with plasmacytoid features from multiple myeloma/plasmacytoma, and diffuse large cell lymphoma from Burkitt's lymphoma.     

Activated proliferation of B-cell lymphomas/leukemias with the SHP1 gene silencing by aberrant CpG methylation

Previously we showed reduced protein and mRNA expression of the SHP1 gene in lymphoma/leukemia cell lines and patient specimens by Northern blot, RT-PCR, Western blot, and immunohistochemical analyses. In this study, aberrant methylation in the SHP1 gene promoter was detected in many B-cell leukemia/lymphoma cell lines as well as in patient specimens, including diffuse large B-cell lymphoma (methylation frequency 93%), MALT lymphoma (82%), mantle cell lymphoma (75%), plasmacytoma (100%) and follicular lymphoma (96%) by methylation-specific PCR, bisulfite sequencing, and restriction enzyme-mediated PCR analyses. The methylation frequency was significantly higher in high-grade MALT lymphoma cases (100%) than in low-grade MALT lymphoma cases (70%), which correlated well with the frequency of no expression of SHP1 protein in high-grade (80%) and low-grade MALT lymphoma (54%). It suggests that the SHP1 gene silencing with aberrant CpG methylation relates to the lymphoma progression. SHP1 protein expression was recovered in B-cell lines after the treatment of the demethylating reagent: 5-aza-2'-deoxycytidine. Transfection of the intact SHP1 gene to the hematopoietic cultured cells, which show no expression of the SHP1 gene, induced growth inhibition, indicating that gene silencing of the SHP1 gene by aberrant methylation plays an important role to get the growth advantage of the malignant lymphoma/leukemia cells. The extraordinarily high frequency (75 to 100%) of CpG methylation of the SHP1 gene in B-cell lymphoma/leukemia patient specimens indicates that the SHP1 gene silencing is one of the critical events to the onset of malignant lymphomas/leukemias as well as important implications for the diagnostic or prognostic markers and the target of gene therapy. These data support the possibility that the SHP1 gene is one of the tumor suppressor genes.     

B-cell lymphomas with coexpression of CD5 and CD10

Coexpression of CD5 and CD10 is highly unusual in B-cell lymphomas and may pose a diagnostic challenge. We report 42 cases of B-cell lymphoma with simultaneous expression of CD5 and CD10. They made up approximately 0.4% of all B-cell lymphomas seen during the study period and included the following cases: large B-cell lymphoma (LBCL), 14 (33%); follicular lymphoma (FL), 10 (24%); mantle cell lymphoma (MCL), 9 (21%); chronic lymphocytic leukemia, 4 (10%); acute precursor B-cell lymphoblastic leukemia/lymphoma, 2 (5%); and other low-grade B-cell lymphomas, 3 (7%). All MCLs had overexpression of bcl-1 or the t(11;14) and were CD43+. All FLs had typical histomorphologic features and were bcl-2+ and bcl-6+ but CD43-. Of 14 LBCLs, 5 were histologically high-grade. Six (43%) of 14 patients with LBCL died within 10 months of diagnosis of CD5+CD10+ lymphoma (median survival, 4 months), including all 3 patients with stage IV disease and 2 of 5 with histologically high-grade lymphoma. Our findings indicate that coexpression of CD5 and CD10 is rare but occurs in diverse subtypes of B-cell lymphoma. Investigation of bcl-1, bcl-6, and CD43 and morphologic evaluation may resolve the potential confusion in diagnosis and lead to the recognition of the correct lymphoma subtype.     

The Leukocyte Semaphorin CD100 Is Expressed in Most T-Cell, but Few B-Cell, Non-Hodgkin’s Lymphomas

The 150-kd transmembrane protein CD100 is the first semaphorin protein shown to be expressed in lymphoid tissue. CD100 is present in the interfollicular T cell zones and is also expressed by B cells in the germinal centers of secondary lymphoid follicles, but not in the mantle zones. The CD100 molecule was recently cloned, and CD100 transfectants were shown to induce homotypic aggregation of human B cells and improve their viability in vitro, suggesting that CD100 may play a role in lymphocyte aggregation and germinal center formation. We studied the expression of CD100 in 138 clinical cases representing a range of lymphoproliferative disorders, to determine whether this molecule is expressed in these neoplastic processes. In general, we found CD100 expression to be common in peripheral T-cell non-Hodgkin’s lymphomas but rare in B-cell non-Hodgkin’s lymphomas. CD100 expression was not detectable in low-grade B-cell non-Hodgkin’s lymphomas, including cases of small lymphocytic lymphoma (18 cases), marginal zone lymphoma (10 cases), and mantle cell lymphoma (10 cases), as might be expected for these neoplasms that are not of follicular center cell origin. Surprisingly, we found that the vast majority of follicular lymphomas (37 of 40 cases) as well as diffuse large-cell lymphomas of B-cell type (35 cases) did not express CD100. The neoplastic cells in 3 of 11 cases of predominantly large-cell-type follicular lymphoma did express CD100. In contrast, all five cases of high-grade, small non-cleaved (Burkitt-like) B-cell lymphoma were immunoreactive for CD100 expression, as were 18 of 20 cases (90%) of malignant T cell neoplasms. Northern blot analysis of CD100 expression correlated with immunohistochemical findings. Absence of expression of CD100 by neoplastic follicular center B cells is a common feature in follicular lymphomas, but expression of CD100 by T cells is maintained in T-cell lymphoproliferative disorders.     

CD56-positive large B-cell lymphoma.

CD56 (NCAM), a neural adhesion molecule, is normally expressed on natural killer cells and subsets of T cells and is commonly seen on hematolymphoid neoplasms such as plasma cell myeloma and acute myelogenous leukemia. It is uncommon in B-cell lymphoma. From 2001 to 2003 a cohort of 20 cases of CD56 B-cell lymphomas was identified by flow cytometry (<0.5% of all B-cell lymphomas studied) during a 2-year period. Most (90%) expressed CD10 and 5/5 tested cases were BCL6, suggesting a follicular origin. An extranodal disease presentation was seen in 45% and may be related to CD56 expression. These CD56 B-cell lymphomas may represent a new subset of large B-cell lymphoma. The relationship of cells with this antigenic profile to normal B-cell differentiation is explored.     

Retrospective study of 82 cases of canine lymphoma in Austria based on the Working Formulation and immunophenotyping

In human beings the prevalence of different non-Hodgkin's lymphoma (NHL) subtypes varies according to geographical region. The aim of this study was to classify canine lymphomas in Austria and to compare the results with those of similar studies in other countries. Eighty-two NHLs were classified according to their morphology (based on the Working Formulation) and their immunophenotype (determined with anti-T-cell and anti-B-cell antibodies). Forty-two (51.2%) were of B-cell subtype, 24 (29.3%) of T-cell subtype, and 16 (19.5%) remained unclassified, because of either negative labelling (9/16) or immunoreaction with both antibodies (7/16). Diffuse lymphomas predominated (99%) over follicular lymphomas, while intermediate grade lymphomas (61%) outnumbered high-grade lymphomas (23.2%) and low grade lymphomas (13.4%). The most common subtype was the diffuse large cell lymphoma (40.2%), followed by the large cell immunoblastic lymphoma (13.4%) and the diffuse small lymphocytic lymphoma (13.4%). Follicular large cell lymphoma and small noncleaved cell lymphoma were uncommon (1.2%). Generally, these findings accord with those of similar studies in Western Europe, making the existence of specific risk factors in Austria unlikely.     

Expression of adhesion molecules in primary B-cell gastric lymphoma and lymphoid follicles

To determine whether primary B-cell gastric lymphoma (GL) is one entity, we examined the expression of three adhesion molecules in the microvasculature of lymphomas. Stromal cells, including vascular endothelial cells, within lymphoid follicles of the gastric mucosa were also investigated. Twenty-two surgical specimens of GL were classified into low-grade malignant lymphoma arising from mucosa-associated lymphoid tissue (low-grade lymphoma, n=9), and high-grade malignant lymphoma with (secondary high-grade lymphoma, n=6) or without (primary high-grade lymphoma, n=7) a low-grade component. The proportion of venules positive for ELAM-1 or VCAM-1 was significantly higher (P<0.001) in primary high-grade lymphoma than in low-grade and secondary high-grade lymphomas. In gastric lymphoid follicles, the stromal cells of the germinal centre (GC) were positive for ICAM-1, ELAM-1, and VCAM-1, but the stromal cells of the marginal zone (MZ) were positive only for ICAM-1. We found two patterns of adhesion molecule expression in gastric lymphoid follicles, the MZ pattern and the GC pattern. Low-grade and secondary high-grade lymphomas, which had the MZ pattern, might be of MZ-cell lineage, but most primary high-grade lymphomas, which had the GC pattern, might be of follicular centre cell lineage.     

Lack of surface immunoglobulin light chain expression by flow cytometric immunophenotyping can help diagnose peripheral B-cell lymphoma

We determined the prevalence and significance of finding B cells without surface immunoglobulin (SIg) light chain expression. The flow cytometry database at Johns Hopkins Medical Institutions was searched for cases in which immunoglobulin light chain staining was performed to rule out a B-cell malignant neoplasm between January 1994 and February 2000. We excluded plasma cell dyscrasias, precursor B-cell acute lymphoblastic leukemia/lymphomas, and hematogones. Cases with more than 25% of B cells lacking SIg light chain expression were retrieved. Polymerase chain reaction assays for immunoglobulin heavy chain gene rearrangements were performed in SIg-negative cases with available tissue blocks. We identified 36 cases; all represented lymphoma. Their diagnoses included diffuse large B-cell lymphoma (20), HIV-related lymphoma (5), follicular lymphoma (5), Burkitt lymphoma (2), monomorphic posttransplant lymphoproliferative disorder (1), chronic lymphocytic leukemia/small lymphocytic lymphoma (1), marginal zone B-cell lymphoma (1), and low grade B-cell lymphoma (1). Of the 17 SIg-negative cases with amplifiable DNAs, 12 (71%) showed a clonal immunoglobulin heavy chain gene rearrangement. SIg-negative B-cell lymphomas are rare. Complete absence of SIg light chain expression in a mature B cell proliferation can be used as a surrogate marker to help diagnose peripheral B-cell lymphoma.     

Proteomic profiling of mature CD10+ B-cell lymphomas

Proteomic profiling with protein-chip technology has been used successfully to discover biomarkers with potential clinical usefulness in several cancer types. Little proteomic study has been done in B-cell lymphomas. We determined whether the expression of a set of proteins by protein-chip technology coupled with new informatics tools could be used to build a model to molecularly classify B-cell lymphoma subgroups. We used surface-enhanced laser desorption/ionization time-of-flight mass spectrometry to analyze 18 CD10+ B-cell lymphomas, including 6 grade 1 (G1) follicular lymphomas (FLs), 7 grade 3 (G3) FLs, and 5 Burkitt lymphomas. We used 7 reactive follicular hyperplasia cases as a control group. By using SAX2 ProteinChip arrays (Ciphergen Biosystems, Fremont, CA), we found a unique protein expression profile for each type of lesion. Two-way hierarchical clustering analysis of these protein expression profiles differentiated reactive follicular hyperplasia, FL, and Burkitt lymphoma, with 5 major clusters of differentially expressed protein peaks. In addition, we identified histone H4 as a potential differentially expressed protein marker that seems to distinguish G1 from G3 FL. To our knowledge, this is the first proteomic study using protein-chip technology for molecular classification of B-cell lymphoma subtypes with clinical samples.     

Frequent deletions of 6q23–24 in B-cell non-Hodgkin's lymphomas detected by fluorescence in situ hybridization

Deletions of the long arm of chromosome 6 (6q) are among the most frequent chromosome aberrations in malignant lymphomas and often occur as secondary changes in addition to typical translocations, such as t(14; 18). Using fluorescence in situ hybridization (FISH) with two YAC probes hybridizing to 6q23–24 and with the centromeric probe D6Z1 as internal control, we studied 31 cases of low-grade and eight cases of high-grade B-cell lymphoma. Deletions of 6q23–24 were detected in 21 patients (56.8%) by FISH, compared to 13 patients (33.3%) by chromosome analysis. Deletions of 6q23–24 were found by FISH in 5 of 13 cases of small lymphocytic lymphoma, in 2 of 3 cases of mantle cell lymphoma, in 10 of 14 cases of t(14; 18) positive low-grade follicular lymphoma, and in 4 of 8 cases of high-grade follicular lymphoma. This study shows that deletions of 6q23–24 are more frequent in B-cell lymphomas than previously suggested and that they can be detected more sensitively by FISH than by chromosome analysis. Contrary to previous reports indicating that the region 6q23–24 is preferentially deleted in low-grade lymphomas without t(14; 18), our results indicate that deletions of 6q23–24 appear to be common in other pathological subsets of B-cell lymphoma as well, especially in follicular lymphomas with t(14; 18). Genes Chromosom. Cancer 18:310–313, 1997. © 1997 Wiley-Liss, Inc.     

Gene rearrangement of bcl-1 and bcl-2 is confined to distinct subgroups of high-grade malignant B-cell lymphomas

The occurrence of bcl-1 and bcl-2 gene rearrangements was investigated in 37 cases of high-grade B-cell lymphomas. Bcl-2 rearrangement was detectable only in single cases of primary centroblastic lymphoma with a follicular growth pattern, whereas secondary centroblastic lymphomas evolving from a centroblastic–centrocytic lymphoma were positive in up to 60 per cent of the cases analysed. Bcl-1 rearrangement was found only in one case of immunoblastic B-cell lymphoma with a history of a pre-existing lymphoplasmacytoid immunocytoma. It is concluded that there may be a subgroup of centroblastic lymphomas with a biology similar to that of centroblastic–centrocytic lymphomas. The detection of bcl-1 rearrangement in high-grade lymphomas may indicate a secondary high-grade lymphoma.     

Expression of CD10, CD75 and CD43 in MALT lymphoma and their usefulness in discriminating MALT lymphoma from follicular lymphoma and chronic gastritis.

AIMS: While it may be difficult to discriminate between chronic gastritis, MALT lymphoma and a gastric location of a nodal lymphoma using histology of small endoscopic biopsies alone, additional markers like CD10, CD75 and CD43 and proliferative activity may be of value. We assessed the expression of these antigens in MALT lymphoma and their usefulness in discriminating MALT lymphoma from follicular lymphoma and from gastritis. METHODS AND RESULTS: Tissue samples of 38 patients with gastric MALT lymphoma were immunohistochemically stained for expression of CD10, CD75 and/or CD43. Proliferation index was scored using MIB-1 staining. Ten cases of nodal follicle centre B-cell lymphomas (n = 11) and 18 cases of high-grade MALT lymphoma (n = 22) showed moderate to high CD75 expression (25-100% positive cells). All tested low-grade MALT lymphomas (n = 9) and chronic gastritis (n = 6) were negative (0-25%) for CD75. All MALT lymphomas (n = 25) were negative for CD10. High-grade lymphomas show significantly higher proliferation indices (67% vs. 16%) than low-grade lymphomas. Only four of 26 MALT lymphomas were slightly positive for CD43. All gastritis biopsies (n = 4) were negative for CD43. CONCLUSIONS: These data suggest that combining both CD10 and CD75 may be useful in discriminating between low-grade MALT, high-grade MALT lymphoma and extranodal location of follicular lymphoma. However, CD43 expression cannot in the majority of cases be used to distinguish between low-grade MALT lymphoma and gastritis.     

Expression of Grb2 distinguishes classical Hodgkin lymphomas from primary mediastinal B-cell lymphomas and other diffuse large B-cell lymphomas

Growth factor receptor-bound protein 2 is an adaptor molecule that mediates B-cell receptor (BCR) signaling pathways, but the expression of growth factor receptor-bound protein 2 in lymphoma tissues has not been reported. We sought to characterize growth factor receptor-bound protein 2 protein expression in reactive tonsillar tissues and lymphoma tissues obtained from diagnostic biopsies of classical Hodgkin lymphoma, primary mediastinal large B-cell lymphoma, diffuse large B-cell lymphoma, nodular lymphocyte predominant Hodgkin lymphoma, and 20 low-grade B-cell lymphomas. Growth factor receptor-bound protein 2 expression was assessed in tissues by immunohistochemistry and in lymphoma cell lines by immunoblotting. In reactive lymphoid tissues, growth factor receptor-bound protein 2 was expressed in the cytoplasm of B-cells and histiocytes but not T-cells. Strong, cytoplasmic growth factor receptor-bound protein 2 expression was seen in the neoplastic cells of follicular lymphoma, chronic lymphocytic leukemia/small lymphocytic lymphoma, splenic marginal zone lymphoma, primary mediastinal large B-cell lymphoma, diffuse large B-cell lymphoma, and nodular lymphocyte predominant Hodgkin lymphoma. In contrast, only 10% of the classical Hodgkin lymphomas showed growth factor receptor-bound protein 2 expression in the neoplastic cells. Growth factor receptor-bound protein 2 protein expression was detected by Western blotting in all lymphoma cell lines tested with higher levels in primary mediastinal large B-cell lymphoma compared with classical Hodgkin lymphoma cell lines. These findings support a role for growth factor receptor-bound protein 2 in the diagnostically challenging workup of classical Hodgkin lymphoma versus primary mediastinal large B-cell lymphoma and warrant further studies to evaluate the biologic significance of growth factor receptor-bound protein 2 in the pathogenesis of classical Hodgkin lymphoma.     

Mutational analysis of the 5' noncoding region of the bcl-6 gene in primary gastric lymphomas.

Bcl-6 mRNA and protein are frequently expressed in the transformed counterparts of the germinal center B-cells, diffuse large B-cell lymphoma and follicular lymphoma, irrespective of the gene rearrangements. Most of the primary gastric lymphomas are thought to be of mucosa-associated lymphoid tissue (MALT) origin, and neither bcl-6 gene rearrangement nor protein expression is found in low-grade gastric lymphomas of the MALT type as in normal marginal zone cells. However, bcl-6 protein expression was identified in high-grade gastric lymphomas, suggesting its role in high-grade transformation. In this study, polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) analysis for bcl-6 primer was performed in order to ascertain the molecular mechanisms of bcl-6 protein expression in primary gastric lymphomas. A total 31 cases of gastric lymphoma were classified into low-grade gastric lymphomas of MALT type (n = 13), high-grade gastric lymphomas of MALT type (n = 6) and gastric diffuse large B-cell lymphomas (n = 12). Bcl-6 mutations were observed in 11 of 13 (84.6%) low-grade gastric lymphomas of the MALT type and in 8 of 12 (66.7%) diffuse large B-cell gastric lymphomas. In 6 cases of the high-grade gastric lymphomas of the MALT type, both the low- and high-grade components demonstrated the same frequency (3/6, 50%) of mutations. The tissue obtained from the marginal zone of Peyer's patch by microdissection technique revealed no bcl-6 mutations by the PCR-SSCP analysis. These findings suggest that the acquisition process of bcl-6 mutations by the marginal zone cells may be involved in the lymphomagenesis of the stomach, but our data does not explain the reason why bcl-6 protein is expressed only in high-grade gastric lymphomas.     

Infrequent bax gene mutations in B-cell lymphomas

Mutation of the bax gene has been reported previously in lymphoid cell lines. In vitro experiments have shown that alterations in promoter and coding sequences of the gene abolish its apoptosis initiation function, which is considered crucial for tumour development. To assess bax gene mutations in lymphomagenesis, polymerase chain reaction-based single strand conformation polymorphism analysis (PCR-SSCP) and direct sequencing were used to detect altered sequences in the promoter region and all the six exons and their flanking sequences of the gene. Nodal and extranodal B-cell lymphomas (n = 112) including follicular lymphoma, mantle cell lymphoma, diffuse large B-cell lymphoma, splenic marginal zone B-cell lymphoma and low- and high-grade mucosa-associated lymphoid tissue (MALT) lymphomas were studied. Sequence alterations were found in 11 cases. Nine also showed the same altered sequences in corresponding non-tumour control tissue samples, indicating polymorphism. In the remaining two cases, sequence alterations (in exons 3 and 6) which altered the bax open reading frame were observed only in tumour tissues, indicating tumour-specific point mutation. These results suggest that inhibition of apoptosis through bax gene mutations is unlikely to be a common event in B-cell lymphoma, at least in the major types of nodal and extranodal B-cell lymphomas.     

Activation of the TCL1 protein in B cell lymphomas

The TCL1 gene, localized near the break point of chromosome 14q32.1 often involved in T cell leukemias, is also expressed in normal precursor T and B cells, and B cell lymphoma cell lines. We investigated the expression of the TCL1 protein in various types of B cell lymphomas according to the Revised European-American Classification of Lymphoid neoplasms. Paraffin-embedded tissue sections of lymphoma specimens were subjected to TCL1 immunohistochemistry, and positivity was scored on a three-tiered scale: - (< 25% cells), + (25-50% cells), and ++ (> 50% cells). The TCL1 protein was expressed in low-grade B cell lymphomas including mucosa-associated lymphoid tissue type in ocular adnexa (18/20, 90%). It was also expressed in follicular, lymphoplasmacytic, and mantle cell lymphoma, but not in high-grade diffuse large B cell lymphoma (2/11, 18%). These data suggest that the expression of the TCL1 gene characterizes low-grade B cell lymphomas, and may be involved in certain processes of lymphomatogenesis.     

Analysis of BCL2 and MYC expression in non-Hodgkin's lymphomas by in situ hybridization: correlation with chromosome translocations.

We have used an in situ hybridization method for analysis of expression of BCL2 and MYC on cytospun preparations of normal and malignant lymphoid cell lines and tissue sections of normal and malignant lymph nodes. The probes comprised 50-mer antisense oligonucleotides starting at the ATG codons of exon 3 of BCL2 and exon 2 of MYC. We studied the expression of these two genes in frozen tissue sections of biopsy specimens derived from normal and hyperplastic lymph nodes, B-cell lymphomas carrying the t(14;18)(q32;q21) and t(8;14)(q24;q32) translocations, and T-cell lymphomas with clonal chromosome abnormalities. While all proliferating cells expressed both genes, BCL2 expression was increased two- to threefold in follicular lymphomas with t(14;18) and MYC expression was increased two- to four-fold in high-grade lymphomas with t(8;14). These results are consistent with previous data on deregulated expression of these genes obtained from study of lymphoma cell lines carrying the relevant translocations.     

Programmed death 1 is a marker of angioimmunoblastic T-cell lymphoma and B-cell small lymphocytic lymphoma/chronic lymphocytic leukemia

Programmed death 1 (PD-1) is a lymphoid receptor that negatively regulates immune responses. PD-1 expression was recently reported in some T-cell non-Hodgkin lymphoma (NHL) subtypes, but the expression profile of PD-1 and its ligands (PD-L1 and PD-L2) in B-NHLs remains largely to be characterized. To investigate this issue, monoclonal antibodies against PD-1, PD-L1, and PD-L2 were generated by immunization of balb-c mice. A series of 161 lymphoma tissue and 11 blood samples was analyzed using either immunohistochemistry or flow cytometry. In reactive lymph nodes, PD-1 was mainly expressed in follicular T cells. In B-NHLs, PD-1 was mainly expressed in reactive T cells; but expression was also noted in neoplastic B cells from small lymphocytic lymphoma (SLL, 12/13), grade III follicular lymphoma (3/3), and diffuse large cell lymphoma (2/25). In contrast, neoplastic B cells from mantle cell lymphoma (0/11), marginal zone lymphoma (0/12), Burkitt lymphoma (0/3), and grade 1 to 2 follicular lymphoma (0/40) were PD-1 negative. PD-L1 and PD-L2 were negative in small B-cell lymphomas, including B-SLL. Flow cytometry showed that blood cells from chronic lymphocytic leukemia (B-CLL) also displayed PD-1 expression, which could be increased by CD40 stimulation. PD-1 expression in T-NHLs was restricted to the angioimmunoblastic subtype (8/8). These results show that PD-1 expression among B-NHLs is mainly associated with SLL/CLL and is influenced by activation of the CD40/CD40L pathway. Because the anti-PD-1.6.4 antibody works on paraffin sections, it represents a useful tool to differentiate SLL/CLL from other small B-cell lymphomas.     

IL-2 receptor expression in human lymphoid lesions. Immunohistochemical study of 166 cases.

Interleukin-2 (IL-2) receptor expression is a feature of T-cell activation and T-cell neoplasia. Expression of the IL-2 receptor in human lymphoid lesions was studied in a series of 166 immunophenotyped cases, including nodal and extranodal reactive lymphoid proliferations (44 cases), low-grade B-cell lymphomas (27 cases), intermediate and high grade B cell lymphomas (42 cases), peripheral T-cell lymphomas (13 cases), Hodgkin's disease (12 cases), histiocytic proliferations (15 cases), nonhematopoietic tumors (16 cases), and miscellaneous lesions (7 cases). Low levels of receptor expression were seen in reactive lymphoid lesions, low-grade B-cell lymphomas, and nonhematopoietic tumors (20%, 7%, and 25% of cases, respectively, with greater than 10% positive cells). High levels of receptor expression were seen in cases of peripheral T-cell lymphoma and histiocytic proliferations (86% and 100% of cases, respectively, with greater than 10% positive cells). Intermediate levels of expression were seen in Hodgkin's disease (including Reed-Sternberg cells) and some cases of intermediate and high-grade B-cell lymphomas (58% and 50% of cases, respectively, with greater than 10% positive cells). IL-2 receptor expression is not confined to T-cell neoplasia, but is also a feature of neoplastic and nonneoplastic histiocytic proliferations, Hodgkin's disease, and some intermediate and high-grade B-cell lymphomas. Biologic and therapeutic implications are discussed.