Immunohistologic identification of phenotypic antigens associated with Hodgkin and Reed-Sternberg cells. A paraffin section study

Proteomics analysis of Hodgkin lymphoma: identification of new players involved in the cross-talk between HRS cells and infiltrating lymphocytes

Hodgkin and Reed-Sternberg (HRS) cells in Hodgkin lymphoma (HL) secrete factors that interact with inflammatory background cells and may serve as biomarkers for disease activity. To detect new proteins related to pathogenesis, we analyzed the secretome of HRS cells. Proteins in cell culture supernatant of 4 HL cell lines were identified using 1DGE followed by in-gel trypsin digestion and LC-MS/MS. In total, 1290 proteins, including 368 secreted proteins, were identified. Functional grouping of secreted proteins revealed 37 proteins involved in immune response. Sixteen of the 37 proteins (ie, ALCAM, Cathepsin C, Cathepsin S, CD100, CD150, CD26, CD44, CD63, CD71, Fractal-kine, IL1R2, IL25, IP-10, MIF, RANTES, and TARC) were validated in HL cell lines and patient material using immunohistochemistry and/or ELISA. Expression of all 16 proteins was confirmed in HL cell lines, and 15 were also confirmed in HL tissues. Seven proteins (ALCAM, cathepsin S, CD26, CD44, IL1R2, MIF, and TARC) revealed significantly elevated levels in patient plasma compared with healthy controls. Proteomics analyses of HL cell line supernatant allowed detection of new secreted proteins, which may add to our insights in the interaction between HRS cells and infiltrating lymphocytes and in some instances might serve as biomarkers.

Nodular type of lymphocyte predominant Hodgkin's disease. A clinical study of 50 cases

BACKGROUND

Lymphocyte predominant Hodgkin's disease (LP-HD), particularly that with a nodular pattern has been suggested to constitute a distinct disorder within the spectrum of Hodgkin's disease, this issue being based on clinical, morphological and immunological observations. Furthermore, the nodular LP-HD (N-LP-HD) has been considered to differ from the diffuse subtype (D-LP-HD), although the data are conflicting. The question addressed in this study was whether the clinical course of N-LP-HD differs from that of the D-LP-HD as well as the other subtypes of Hodgkin's disease.

PATIENTS AND METHODS

90 cases diagnosed as LP-HD at St. Bartholomew's Hospital (SBH) were reviewed. The histopathological classification was based on the original Lukes and Butler criteria for classical N-LP-HD. Clinical data were retrieved from case notes and a computer database. Stage was determined by the Ann Arbor criteria. Survival and remission duration analyses were performed for the group of patients with N-LP-HD and compared with an histological control group of patients with the other subtypes of Hodgkin's disease and the cases of LP-HD that have been reclassified.

RESULTS

1. 50/90 cases (56%) originally diagnosed as N-LP-HD qualified as N-LP-HD. No case with the diffuse subtype, could be identified. Twenty-three percent of the cases were reclassified as Mixed Cellularity and 11% as Nodular Sclerosis HD, whilst 10% as non-Hodgkin's lymphomas. 2. The majority of cases (78%) presented with early stage (I + II). Bone marrow and liver involvement were rare. 3. 92% of cases achieved complete remission. Recurrence developed in only 6/46 patients within 5-12 years. A second complete remission was achieved in 5/6 (83%) cases. Further recurrences have not yet occurred. 4. The overall survival of the 50 cases with N-LP-HD was 92% at 4 years and did not differ significantly from the 40 cases that have been reclassified. Remission duration however, was significantly better for the group of N-LP-HD being 81% at 12 years. 5. Second malignancies were common and developed in 6/50 cases (12%) with N-LP-HD within 10-15 years. These included: ALL (1 case), high grade B-NHL (2 cases), squamous cell carcinoma (1 case), glioma (1 case), lung carcinoma (1 case). 6. 12/50 patients died within a period of follow-up, up to 21 years. 1/3 of the deaths was attributed to the development of second malignancy.

CONCLUSIONS

The diffuse variant of LP-HD is rare, having not been seen at St. Bartholomew's Hospital during this time period. The 50 cases with N-LP-HD showed a favourable course with presentation at an early stage, good response to treatment, late recurrences and remission duration other than the other subtypes of HD. The latter could be attributable to the early stage at presentation of N-LP-HD, since the remission duration on a matching on stage analysis was superficially better in favour of N-LP-HD (p = 0.06). The indolent course of the disease in combination with the risk of second malignancy cases raises the question whether histology should be taken into consideration in the development of new protocols for HD.

Concordance for Hodgkin's disease in identical twins suggesting genetic susceptibility to the young-adult form of the disease

BACKGROUND

Relatives of young adults with Hodgkin's disease are at increased risk of Hodgkin's disease, and lines of evidence implicate both inheritance and environment.

METHODS

We have identified and followed 432 sets of twins affected by Hodgkin's disease. The number of cases of Hodgkin's disease observed before the age of 50 years in the healthy monozygotic and dizygotic twins of the patients with Hodgkin's disease was compared with the number expected from national age-specific incidence rates.

RESULTS

None of the 187 pairs of dizygotic twins became concordant for Hodgkin's disease, whereas 10 of the 179 pairs of monozygotic twins did; in 5 of these pairs, the second case appeared after the original ascertainment. During the observation period, 0.1 (monozygotic) and 0.1 (dizygotic) cases in the unaffected twins were expected. Monozygotic twins of patients with Hodgkin's disease thus had a greatly increased risk (standardized incidence ratio, 99; 95 percent confidence interval, 48 to 182), whereas no increase in the risk for dizygotic twins of patients with Hodgkin's was observed.

CONCLUSIONS

Genetic susceptibility underlies Hodgkin's disease in young adulthood.

Recent results on the biology of Hodgkin and Reed-Sternberg cells. I. Biopsy material

The most recent sophisticated investigations have provided new and revealing, but also contradictory and controversial information on the biological nature and the cellular origin of Hodgkin and Reed-Sternberg cells (H-RS). Immunophenotypic analyses have shown variable phenotypic antigen expression; but, on balance the data suggest a lymphoid cell expressing T- and/or B-cell-associated markers and certain activation antigens while lacking immunological features of monocytes-macrophages or other lineages. Molecular genetic studies have demonstrated heterogenous findings with respect to rearrangements of T-cell receptor and immunoglobulin genes. Only a small percentage of the cases has rearrangements; this might be due to the threshold of sensitivity of the method combined with the scarcity of the malignant cells. Epstein-Barr virus (EBV) genomes are clonally integrated in the H-RS cells of about half the cases. The significance of these findings--whether EBV is a causative agent or an epiphenomenon--remains to be elucidated. H-RS cells express mRNA and proteins of various cytokines and cytokine receptors implying a predominant role for cytokines in the pathophysiology of HD. The mononuclear and polynuclear H-RS cells are capable of DNA synthesis and nuclear division; the lack of cellular division leads to multinuclearity through the process of endomitosis. Mutations and expression of only a limited number of oncogenes have been tested thus far. Whether the bcl-2 oncogene is involved in HD remains a matter of debate. Aneuploidy and non-random chromosomal abnormalities are the results of cytogenetic analyses of H-RS cells. However, no chromosomal marker specific for HD has yet been found. Thus, while studies of EBV involvement, growth factor production, oncogene expression and chromosomal abnormalities contributed a fair amount of new data on the nature of H-RS cells, only immunophenotyping and genotyping provided some indication of the cellular derivation: an activated lymphoid cell that possibly expresses oncogenes, that probably is infected with EBV, that most likely produces cytokines, that certainly has multiple karyotypic abnormalities.

Lymphocyte predominance Hodgkin's disease (nodular paragranuloma)--a bcl-2 negative germinal centre lymphoma

Hodgkin's disease, lymphocyte predominance type (nodular paragranuloma), is of germinal centre origin and the tumour cells have a B-cell phenotype. As the T(14;18) translocation, and the subsequent expression of bcl-2 protein by germinal centre cells, is the most characteristic finding of centroblastic-centrocytic lymphoma, we have tested a series of 11 cases of lymphocyte predominance Hodgkin's disease, using Southern blot analysis for the major breakpoint region and the minor breakpoint cluster region, polymerase chain reaction with primers for the major and minor breakpoint cluster region, and immunohistological studies with a monoclonal antibody specific for the bcl-2 protein. All three techniques gave negative results in the cases of Hodgkin's disease, establishing a clear differentiation from centroblastic-centrocytic lymphoma. These findings are useful in the differential diagnosis between the two entities and raise the question of the non-clonal nature of lymphocyte predominance Hodgkin's disease.

Anti-BLA.36 monoclonal antibody shows reactivity with Hodgkin's cells and B lymphocytes in frozen and paraffin-embedded tissues

A newly developed monoclonal antibody, anti-BLA.36, raised against a Hodgkin cell line, was shown to have reactivity with Reed-Sternberg cells and activated B lymphocytes and appears to be distinct from other antibodies which identify antigens of hematopoietic cells. Anti-BLA.36 was evaluated in B5-fixed paraffin-embedded tissue from 16 cases of Hodgkin's disease of various types and 35 cases of non-Hodgkin's lymphomas representative of the different major subtypes. The specificity of anti-BLA.36 was compared with other antibodies that have been used to mark Hodgkin's cells and B lymphocytes: namely, L26, LN-1, Leu-M1 and Ber-H2, as well as UCHL-1, a pan-T lymphocyte marker. In addition, a subset of the cases was evaluated using frozen tissue in order to validate the staining characteristics of anti-BLA.36 as observed in fixed paraffin sections. Anti-BLA.36 was found to react with Hodgkin's cells more consistently than the other antibodies used in this panel. The antibody reacted with an antigen on Reed-Sternberg cells and their variants (Hodgkin's cells) in all four subtypes of Hodgkin's disease, and with a subset of reactive and malignant B lymphocytes, but not with T lymphocytes. It may, therefore, be useful in the evaluation of non-Hodgkin's lymphomas. Finally, this is the first antibody raised to a Hodgkin's cell line which also consistently marks reactive and malignant B cells, but not T cells. The implications of this observation are discussed in relation to the cellular origin of the Reed-Sternberg cell and the overall nature of Hodgkin's disease.

Immunophenotypic study of lymphocyte predominance Hodgkin's disease

An immunophenotypic study of 17 cases of diffuse lymphocyte predominance Hodgkin's disease and 20 cases of nodular lymphocyte predominance Hodgkin's disease, along with eight of mixed cellularity and five of nodular sclerosing Hodgkin's disease, is reported. The atypical cells in nodular lymphocyte predominance Hodgkin's disease showed only minor differences from the published consensus. However, the atypical cells in diffuse lymphocyte predominance Hodgkin's disease showed an immunophenotype which was commonly B-cell positive (59%), but in a minority of cases LeuM1 (24%) or epithelial membrane antigen (12%) positive; none of the cases was Ber-H2 positive. These results do not differ greatly from our findings in nodular lymphocyte predominance Hodgkin's disease, but do diverge from the published consensus for diffuse lymphocyte predominance Hodgkin's disease. The question as to whether morphology or immunophenotype should form the primary diagnostic criterion for the definition of lymphocyte predominance Hodgkin's disease is discussed.

Characterization of giant cells in Hodgkin's lymphomas by immunohistochemistry applied to randomly collected diagnostic biopsies from the German Hodgkin Trial

A panel of 10 monoclonal antibodies reactive with formalin-resistant epitopes was applied to characterize the giant cells of the Reed-Sternberg, Hodgkin, and lacunar cell types in diagnostic biopsies from the German Hodgkin Trial. The 94 tissue samples examined had been sent to the Reference Center by 44 different laboratories which made the initial diagnoses. A board of four referees re-classified the primary diagnoses established by the 44 different histopathologists, providing subtyping of Nodular Sclerosis according to Bennett et al. (1985, 1989). Only cases with unequivocal agreement among the referees and which satisfied standards of fixation and embedding were included. Giant cells stained positively with: Ber-H2 in 92 per cent (81/88), LN-2 in 86.4 per cent (76/88), and DAKO-M1 in 72.2 per cent (64/88) of cases in which the lymphocyte predominance type was not included. Positive staining was quite rare with the other seven monoclonal antibodies. No significant difference in reactivity was revealed between giant cells of Reed-Sternberg, lacunar or Hodgkin cell types. Approximately one third of the cases were negative for at least one of the markers, Ber-H2, LN-2 or DAKO-M1. The lymphocytic and histiocytic cells in lymphocyte predominance Hodgkin's disease displayed a distinctive staining pattern with positivity for B-cell markers, whereas DAKO-M1 and Ber-H2 were predominantly negative. Finally, we found that randomly collected blocks of primary biopsies permit reliable immunostaining by this panel of monoclonal antibodies, since our results agree with results from the literature obtained from biopsies processed according to more uniform protocols for fixation and embedding.

Clinical features associated with transformation of cerebriform T-cell lymphoma to a large cell process

Some patients with cerebriform T-cell lymphoma (CTCL) undergo morphologic transformation to a large cell lymphoma. From a series of 113 patients with CTCL, 22 patients were identified with transformed CTCL. Stages of involvement at diagnosis were: I (seven), II (four), III (four), IV (seven). Nine patients had transformation at the initial diagnosis while the median time from diagnosis to transformation in the other 13 patients was 16 months (range: 3 months-6 years). Thirteen had transformation extracutaneously: lymph nodes (eight), central nervous system (two), and other extranodal sites (three). T cell markers were identified in all cases; of 15 cases with complete phenotypes, there were eight T-helper, three T-suppressor, and four aberrant T phenotypes. Serology for human T-leukemia virus-I (HTLV-I) was negative in eight patients tested. Median survival from diagnosis was 27 months compared to 53 months in 53 patients without transformation (p = 0.003). Despite combination chemotherapy in 12 patients following transformation, median survival after transformation was 12 months and only 7 months with extracutaneous disease. The likelihood of transformation could not be predicted by the initial histology, immunophenotype, or stage of disease.

Lymphocyte predominance Hodgkin's disease--an immunohistochemical study

Lymph node biopsies from 57 local and referred cases, previously diagnosed at Southampton between 1978 and 1987 as lymphocyte predominance Hodgkin's disease were examined using the monoclonal antibodies MT1, UCHL1, L26, LN-1, E29/68 (EMA), Leu-M1 (CD15) and Ber-H2 (CD30). Of the 34 cases with a nodular architecture, 21 (19 male, two female) contained polylobated Reed-Sternberg cell variants with a B-cell phenotype, which lacked expression of CD15. In all cases, the polylobated cells showed positive staining with L26 and LN-1. Six cases expressed EMA and three showed positive staining with Ber-H2. Two cases lacking polylobated cells were reclassified as reactive follicular hyperplasia with progressive transformation of germinal centres. The remaining 11 cases had an atypical immunophenotype and were reclassified, mainly as mixed cellularity Hodgkin's disease. In six cases, the lymph node architecture showed a mixture of nodular and diffuse growth patterns. Five of these cases contained polylobated cells with the typical morphology and immunophenotype of those seen in nodular lymphocyte predominance Hodgkin's disease. The sixth case contained cells expressing CD15, and was reclassified as nodular sclerosing Hodgkin's disease. Of the fifteen biopsies with a diffuse architecture, four contained polylobated B-cells lacking expression of CD15. These were considered to be diffuse lymphocyte predominance Hodgkin's disease. The remaining 11 cases were reclassified as either Hodgkin's disease, mixed cellularity or as T-cell lymphomas.

Expression of Leu M1 antigen on a monoclonal B cell line established from a patient with rheumatoid arthritis

The purpose of this study is to show that anti-Leu M1 antibody (anti-CD15), which has different staining characteristics in lymphoid and non-lymphoid cells, reacted against the surface antigen of a defined monoclonal B cell line. This antibody recognizes the sugar moiety, lacto-N-fucopentaose (LNF-III), which is linked to the cell membrane protein in several kinds of cells, but not in B cells. However, a human monoclonal B-cell line (TKS-1) which was established from the peripheral blood of a patient with rheumatoid arthritis, expressed the Leu M1 antigen spontaneously. The analysis of surface markers using a fluorescence-activated cell sorter (FACS) has revealed that the surface markers of TKS-1 were anti-mu, delta, kappa, HLA-DR, DQ, Leu 12 (CD19) and Leu M1 (CD15). TKS-1 cells were not reactive with any of the following antibodies: anti-OK M1 (CD11b), Leu M2, Leu M3 (CD14), Leu M4, Leu 1 (CD5), Leu 2 (CD8), Leu 3 (CD4), Leu 4 (CD3), Leu 7 and Leu 11 (CD16). In addition, TKS-1 was positive to Epstein-Barr nuclear antigen, weakly positive to non-specific esterase without staining inhibition by NaF, and negative to peroxidase. TKS-1 cells produced IgM in the culture supernatant and have kappa-light chain rearrangement in its DNA. As shown in other studies, distribution of Leu M1 is very wide. This antigen is not a specific immunodiagnostic marker to distinguish the cell type. We conclude that it is possible to express Leu M1 antigen on the membrane of a B-cell lineage cell.

Lymphoma phenotyping in formalin-fixed and paraffin wax-embedded tissues: II. Profiles of reactivity in the various tumour types

Recently, monoclonal antibodies capable of phenotyping malignant lymphomas in routinely fixed and processed tissue have become available. Some of these reagents identify lineage-restricted variants of the leucocyte common molecule, whereas others identify unique fixation-resistant epitopes on lymphoid cells, some of which are shared by non-lymphoid tissues. A new generation of antibodies recognizing 'classical' leucocyte antigens such as CD3 are also emerging. Refinements in antigen detection systems, especially for immunoglobulin recognition, combined with these new reagents promise to improve the accuracy of lymphoma diagnosis in routine histopathology. These new antibodies are reviewed, and their limitations, cross reactivities and profiles of staining in lymphoreticular disease are discussed. A strategy for their optimal use is proposed.

Paraffin section markers for Reed-Sternberg cells. A comparative study of peanut agglutinin, Leu-M1, LN-2, and Ber-H2

Hodgkin's disease (HD) is sometimes difficult to distinguish from non-Hodgkin's lymphomas, and a reliable marker for Reed-Sternberg and related (R-S) cells in paraffin sections would be useful. Ninety-one cases of HD with PNA, anti-Leu M1, and LN-2, and 90 cases with Ber-H2 were studied. The staining results were evaluated independently. R-S cells stained positively with one or more of the reagents in all cases. PNA staining was positive in 78 cases (85.7%); Leu M1, 63 (69.2%); LN-2, 71 (78.0%); and Ber-H2, 80 cases (88.9%). Positively stained cells were readily recognized in 71 cases (91.0%) of PNA+, 51 (80.9%) of Leu M1+, and 51 (71.8%) of LN-2+ and 71 (88.7%) of Ber-H2+ cases; the cells were found only after careful search in the remaining cases. Sixteen cases of peripheral T-cell lymphoma (large cell type, ten; mixed, five; unclassifiable, one) were also stained. Tumor cells did not stain with PNA or anti-Leu M1 in any of the 16 cases but did stain positively with LN-2 in four and with Ber-H2 in five. Thus, the detection rate of R-S cells was the highest with Ber-H2, closely followed by PNA. PNA, however, stained the largest number of R-S cells per case, and the results were least affected by the type of fixative employed. Staining of peripheral T-cell lymphoma appeared to be nil or extremely rare with PNA and Leu M1, whereas it was not uncommon with Ber-H2 and LN-2. In conclusion, to facilitate the detection of R-S cells in paraffin sections, the application of a panel of three markers, PNA, Leu M1, and Ber-H2, appears to be necessary at this point in time.

Plasmacytoid monocytes (so-called plasmacytoid T cells) in Hodgkin's disease

The occurrence and distribution of plasmacytoid monocytes (so-called plasmacytoid T cells) were investigated immunohistochemically in 40 cases of Hodgkin's disease. Large numbers of plasmacytoid monocytes were found in all cases of lymphocyte predominance, nodular sclerosing, and mixed cellularity Hodgkin's disease, characterized by a minor degree of architectural effacement. They occurred at the periphery of lymphoid aggregates which mimic the composite nodule of the reactive lymph node and which contained Reed-Sternberg cells and their variants. Despite some immunophenotypic similarities, no further arguments were found to support a relationship between plasmacytoid monocytes and Reed-Sternberg cells. We conclude that plasmacytoid monocytes represent one of the monocyte-derived cells that contribute to the cellular reaction in Hodgkin's disease.

In situ immunologic characterization of cutaneous involvement in Hodgkin's disease

The current study assesses in situ the antigenic phenotype of cutaneous infiltrate in two cases of Hodgkin's disease affecting the skin. Immunostaining utilized monoclonal antibodies for T-lymphocyte and B-lymphocyte and mononuclear phagocyte markers. The same immunophenotypic pattern of cutaneous infiltrate was observed in both cases, despite a different histopathologic subtype (mixed cellularity in case one, nodular sclerosis in case two). The majority of infiltrating cells expressed T-lymphocyte markers, with a predominance of CD8+ phenotype. Few cells bore B-lymphocyte markers or had DRC-1+ phenotype. No CD1a+ dendritic cell was found in the dermal infiltrate. Variable numbers of cells reacted with mononuclear phagocyte markers. The authors believe that the antigenic phenotype of cutaneous Hodgkin's disease has not previously been reported. The immunophenotypic pattern of skin infiltrate is different from that described in lymphoid tissues. Such findings could be related to the previous therapy or to the possible influence of skin microenvironment.

Immunophenotyping of hematopoietic malignancies in paraffin sections

Immunophenotyping of hematopoietic malignancies is usually accomplished in frozen sections or cell suspensions. To determine whether this procedure was also feasible in paraffin sections, we performed a double-blind immunoperoxidase study of 65 hematopoietic tumors whose phenotypes had been determined previously in fresh tissue. A selected antibody panel was used, including anti-LN2, UCHL-1, anti-cathepsin B, anti-Leu M1, anti-MB2, and anti-MT1. A correct phenotype was obtained on paraffin sections in 95% of cases. All 31 B-cell malignancies were properly classified, showing reactivity for LN2 and MB2. In 14 of 15 T-cell hematopoietic malignancies, all cells reacted with anti-MT1 and/or UCHL-1; the 1 case negative for these antigens was misdiagnosed as a B-cell tumor because of misinterpreted LN2 reactivity in benign histiocytes. Four of 5 true histiocytic neoplasms were positive for cathepsin B and LN2 but lacked other antigens; the fifth case was wrongly considered a B-cell proliferation because only bland histiocytes displayed cathepsin B. Only 1 of 7 Hodgkin's lymphomas was misdiagnosed (as a T-cell tumor); in the other 6 cases, Reed-Sternberg cells were reactive for LN2 and LEU M1. Five of 6 extramedullary myeloid leukemias also stained for LN2, MT1, and LEU M1. One showed LN2, MB2, and MT1; this case was classified as a B-cell neoplasm and indeed represented a pre-B-cell transformation of chronic myelogenous leukemia. These results show that the specified panel of antibodies may be useful for immunophenotyping of hematopoietic neoplasms when only paraffin sections are available for analysis. However, it cannot supplant traditional cell-marker studies of hematopoietic tumors because of its lesser accuracy.

Nodular and diffuse types of lymphocyte predominance Hodgkin's disease

The nodular form of lymphocyte predominance Hodgkin's disease has been shown to be immunophenotypically distinct from the histologically diffuse form and from other types of Hodgkin's disease. We undertook a clinicopathological study of 73 cases to determine whether any clinical differences between the nodular and diffuse subtypes could be discerned. Patients with the diffuse form (n = 41) tended to have a course similar to that of other types of Hodgkin's disease; there were few relapses and only two deaths due to Hodgkin's disease. In contrast, patients with the nodular form (n = 32) had significantly more relapses, which were independent of stage or treatment and equally distributed up to 10 years after initial therapy. Despite the frequent relapses, patients with the nodular form had an indolent course, and there was only one death due to Hodgkin's disease. There were seven fatal second cancers and two non-neoplastic treatment-related deaths, equally distributed between the nodular and diffuse groups. We conclude that nodular lymphocyte predominance Hodgkin's disease may have important clinical as well as immunophenotypic differences from other forms of Hodgkin's disease, and that patients with this condition should be followed carefully because of the possibility of late relapse.

Reed-Sternberg cells and their cell microenvironment in Hodgkin's disease with reference to macrophage-histiocytes and interdigitating reticulum cells

Fifty-eight paraffin-embedded lymph node biopsies from patients with Hodgkin's disease (36 nodular sclerosis, 14 mixed cellularity, five lymphocyte depletion, and three lymphocyte predominance) were immunostained with a panel of monoclonal (anti-Leu-M1, antileukocyte common antigen) and polyclonal (to lysozyme, alpha 1-antitrypsin, alpha 1-antichymotrypsin, and S-100 protein) antibodies by using the avidin-biotin immunoperoxidase technique. Both the immunostaining features of the Reed-Sternberg (R-S) cells and their variants, and the numbers of immunostained accompanying cells morphologically corresponding to macrophage-histiocytes (M-H) and to interdigitating reticulum cells (IRC) were analyzed. Variable numbers of R-S cells and their variants were positive for Leu-M1 in 83% of the cases, for alpha 1-antitrypsin in 40%, for alpha 1-antichymotrypsin in 30%, and for leukocyte common antigen in 3.4%; they were constantly negative for lysozyme and S-100 protein. Whereas the average numbers of accompanying cells immunostained for Leu-M1 were very low, the numbers of S-100-positive IRC were relatively high in all the Hodgkin's subtypes. The average numbers of M-H were lower (P less than 0.1 for lysozyme; P less than 0.001 for alpha 1-antichymotrypsin) in the nodular sclerosis than in the other pooled subtypes. In the nodular sclerosis subtype, however, R-S cells and their variants that stained positive for Leu-M1 appeared to express more frequently the lineage markers of M-H (alpha 1-antitrypsin and/or alpha 1-antichymotrypsin). These data appear to suggest that there is not an apparent qualitative correspondence between the immunostaining features of the cellular microenvironment composed of M-H and IRC and the features of the R-S cells.

Critical assessment of four monoclonal antibodies reactive with B-cells in formalin-fixed paraffin-embedded tissues

Four commercially available monoclonal antibodies, MB1, MB2, LN1 and LN2, were studied to determine their sensitivity and specificity for the diagnosis of B-cell lymphomas when used on formalin-fixed paraffin-embedded tissues. In addition to 125 cases of immunologically characterized non-Hodgkin's lymphoma, a range of normal tissues, reactive lymphoid proliferations, Hodgkin's disease and granulocytic sarcomas were also studied. MB1 was found to give positive results in 53.6% of B-cell lymphomas, but the staining was sometimes weak and patchy; there was also cross-reaction with 1.8% of T-cell lymphomas. MB2 reacted with 88.4% of B-cell lymphomas and the reaction was often strong and diffuse, but it showed cross-reaction with 18.2% of T-cell lymphomas. LN1 and LN2 gave positive staining of 44.9 and 46.4% of B-cell lymphomas respectively, and the results appeared to be inferior to that obtained in B5-fixed tissues; staining was sometimes weak and focal, and they also gave false-positive results in a few cases of T-cell lymphoma. This study shows that MB1, LN1 and LN2 are fairly but not entirely specific for B-cells in the non-Hodgkin's lymphomas, but are not very sensitive when applied to formalin-fixed tissues. MB2 shows a high sensitivity but only moderate specificity. Therefore, when these antibodies are used to determine the immunophenotype of malignant lymphomas, the B-cell nature can be predicted with great confidence only when two, preferably three or more, of the antibodies give positive results. The potential applications of these antibodies are discussed.