Diagnostic and prognostic value of immunohistological bone marrow examination: results in 212 patients with lymphoproliferative disorders

Chronic lymphocytic leukemia/small lymphocytic lymphoma: another neoplasm related to the B-cell follicle?

Although there has been increased attention paid to the critical nature of nodal involvement in chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL), the B-cell compartment it is most closely related to and its relationship to the follicle remain uncertain. A clinicopathologic investigation of 60 extramedullary biopsies of LEF1+ CLL/SLL, including 29 cases with perifollicular/follicular (PF/F) growth, was therefore performed. A subset of PF/F cases demonstrated inner mantle zone preservation or intra-mantle zone growth. All PF/F and 16/31 other cases contained CD21+ follicular dendritic cells. No cytogenetic, IGHV mutational or gene usage differences were seen between PF/F and diffuse cases. PF/F cases were more often kappa positive (p<0.03) and had fewer involved nodal sites (p=0.0004). These findings suggest that at least a subset of bona fide CLL/SLL is related to the follicle, most likely the outer mantle zone, and that at least a subset of the diffuse cases may represent "later" disease.

Structure and function of the hematopoietic cancer niche: focus on chronic lymphocytic leukemia

Chronic Lymphocytic Leukemia (CLL) is a B cell malignancy characterized by the accumulation of mature monoclonal CD5-positive B cells in the blood, secondary lymphoid tissues, and marrow. The infiltration of CLL cells in lymphoid tissues is a key element of disease pathogenesis. It is in such tissues that are found the microenvironments that provide CLL cells protection from spontaneous and/or drug-induced apoptosis. CLL cells actively shape their microenvironment by producing cytokines and chemokines, and by subverting normal accessory cells to promote leukemia-cell survival, proliferation, and escape from immune detection. In this review, we discuss how CLL cells disrupt the niches required for normal hematopoiesis or immune function and subvert normal cells in the microenvironment to support neoplastic cell growth and survival.

Ki67 protein: the immaculate deception?

This article updates our previous review of Ki67 published in Histopathology 10 years ago. In this period the numbers of papers published featuring this antibody has increased 10-fold from 338 to 3489 indicating the considerable enthusiasm with which this antibody has been studied. This review attempts to provide an update on the characterization of the Ki67 protein, its function and its use as a prognostic or diagnostic tool.

CpG island methylation of the hTERT promoter is associated with lower telomerase activity in B-cell lymphocytic leukemia

OBJECTIVE

Expression of the catalytic subunit of the telomerase enzyme hTERT is essential for prolonging the replicative lifespan and is the rate-limiting step in cellular immortalization and carcinogenesis. Because hTERT expression is positively correlated with telomerase activity, its regulation is suggested as the major determinant of enzymatic activity. The hTERT promoter region contains two CpG islands, which are known to be target sites for de novo DNA methylation. To elucidate the impact of this epigenetic mechanism on telomerase activity, we analyzed the degree of hTERT promoter methylation in 30 patients with B-cell chronic lymphocytic leukemia.

MATERIALS AND METHODS

hTERT promoter methylation was assessed using a methylation-specific competitive polymerase chain reaction assay. The assay is based on digestion of genomic DNA with a methylation-sensitive restriction enzyme before amplification with an internal standard.

RESULTS

Patients exhibiting high telomerase activity showed significantly less methylation of the hTERT promoter core domain than patients with low enzyme activity. In addition, telomerase activity was significantly associated with telomere length and overall survival.

CONCLUSIONS

Our data show that the degree of CpG island methylation of the hTERT promoter exhibits an impact on telomerase activity in a subgroup of patients with B-cell chronic lymphocytic leukemia and therefore is assumed to play a role in regulating hTERT gene expression in these patients.

Transplantation of IL-2-transduced murine bone marrow is associated with dose-dependent toxicity

OBJECTIVE

The purpose of this study was to investigate the effects of interleukin-2 (IL-2) gene-transduced hematopoietic progenitor cells or cytotoxic function and systemic toxicity following syngeneic bone marrow transplantation.

MATERIAL AND METHODS

Marrow of 5-fluorouracil pretreated donor mice were transfected with a retroviral vector containing the murine IL-2 gene and transplanted into lethally irradiated syngeneic hosts.

RESULTS

Productive insertion of the IL-2 gene could be demonstrated at various intervals post-transplant without impairment of hematopoietic engraftment. Endogenously augmented IL-2 release resulted in a selective increase in CD4(+), CD8(+), and NK1.1(+) population in spleen and bone marrow, as well as significant cytolytic activity against syngeneic leukemia cells in vitro. Our results also illustrate the interdependence among the magnitude of systemic IL-2 levels, the number of IL-2-transduced cells in the transplant inoculum, and the appearance of systemic toxicity. Infusion of marrow transduced with high-titer, high-expressing IL-2 retrovirus resulted in significant morbidity and mortality in the recipients. Our studies demonstrate that mortality was secondary to severe lymphocytic infiltration of liver and lung, which was associated with increased expression of intercellular adhesion molecule-1 and vascular adhesion molecule-1. Reducing the number of IL-2-transduced cells in the bone marrow inoculum, however, resulted in significantly improved survival with no adverse events being evident during the post-transplant period.

CONCLUSION

Delivery of IL-2 to the bone marrow can be achieved by transplantation of genetically modified hematopoietic cells, however, the overall feasibility is strongly influenced by the number of transduced cells in the bone marrow inocolum and/or the expression pattern of IL-2 in vivo.

Expression of LFA-1 identifies different prognostic subgroups in patients with advanced follicle center lymphoma (FCL)

In a retrospective immunohistochemical study based on 27 patients with stage IV follicle center lymphoma (FCL) the expression of CD44standard (CD44s), LFA-1 (CD11a, CD18), VLA-4 (CD49d, CD29) and ICAM-1 (CD54) was analysed on lymphoma cells in bone marrow infiltrates. The results were correlated to clinical data and overall survival. Our data demonstrate that the expression of LFA-1 on lymphoma cells is predictive for the prognosis of patients with advanced FCL. In detail, patients exhibiting weak to moderate expression (+/++) of CD11 and CD18 showed a significantly shorter median survival (51 months and 33 months, respectively) than did those presenting with strong expression ( ) of the LFA-1 adhesion molecule (P = 0.04 and P = 0.0051, respectively). Furthermore, multivariate analysis identified CD18 as a new independent prognostic factor in patients with advanced FCL. Our findings emphasize the relevance of adhesion molecules for the pathology of FCL and give further support for their impact on clinical course and overall survival.

Cold acetone fixation and methacrylate embedding. A suitable method for routine processing of bone marrow biopsies

Here we report that acetone fixation at -18 degrees C with subsequent embedding in methyl-/butylmethacrylate is a reliable method for the routine processing of bone marrow biopsies. This method allows good conventional histological visualization of morphological details, which is comparable with other fixation procedures. The essential advantage of this method is that a wide range of monoclonal antibodies and polyclonal antisera can be used for immunohistochemical investigations for diagnostic and scientific purposes. The addition of 5% polyethylene glycol 400 to the acetone minimizes freeze-related artefacts. The immunohistochemical demonstration of a number of antigens is mostly affected by the medium used for slide preparation and to a lesser extent by the concentration of benzoylperoxide used for polymerization. Performing polymerization at 4 degrees C and using N, N-dimethyl-p-toluidine as accelerator allows the concentration of benzoylperoxide to be reduced to 0.2 g% (8.3 mmol). Under these conditions the methacrylate embedding procedure has only minimal effects on the quality of immuno- and enzyme histochemistry. Additionally, the simplified method for removing the polymerization inhibitor from the methacrylate components and the shortened impregnation step are further advantages of the embedding method described here.

Assessment of the value of immunohistochemistry in the subtyping of acute leukemia on routinely processed bone marrow biopsy specimens with particular reference to macrophage-associated antibodies

The value of immunohistochemical staining in the subtyping of acute leukemia was investigated on 36 routinely processed (formalin-fixed and paraffin-embedded) trephine biopsy specimens from the iliac crest containing diffuse infiltrates of acute myelogenous leukemia (AML; n = 23) and acute lymphoblastic leukemia (ALL; n = 13). These were stained with a broad panel of antibodies (n = 23) against various leukocyte antigens, among them 11 macrophage-associated antibodies (MAAs): Ki-M1p, MAC387, HAM56, LN5, KP1 (CD68), PG-M1 (CD68), Ki-M4p, DAKO-DRC (CD35), and antibodies against lysozyme, alpha 1-antichymotrypsin, and S100 protein. The French-American-British (FAB) classification subtypes of the AML cases, as determined by enzyme-cytochemical and/or immunocytological investigation of bone marrow smears, were as follows: M1 = 6, M2 = 5, M4 = 7, M5 = 3, and AML (not classified) = 2. The 13 cases of ALL were classified as follows: c-ALL (pre-B-ALL) = 7, B-ALL = 3, T-ALL = 2, and ALL (not classified) = 1. All the MAAs except LN5, Ki-M4p, and DAKO-DRC stained blast cells in AML. However, the number of stained blast cells varied considerably within and between the individual subtypes (M4/5 > M2/1). Using Fisher's exact test a significant difference in frequency of blast cell staining between AML and ALL was found for four MAAs (anti-lysozyme, MAC387, Ki-M1p, and KP1) and two of the three myeloid cell markers applied (Ki-My2p and anti-neutrophil elastase). Of these six antibodies, the combination of anti-lysozyme and KP1 can be recommended for use in routine diagnostics for the differentiation of AML from ALL on the basis of immunohistochemical staining because both of these antibodies were found to stain a relatively large percentage of cases of AML but none of ALL. However, none of the MAAs were found to discriminate reliably between the FAB M4/5 and M1/2 subtypes of AML.

Bone marrow lymphocyte subsets in myelodysplastic syndromes

AIM

To examine lymphocyte subsets in patients with myelodysplastic syndromes (MDS); and to correlate immunohistological variables with prognosis.

METHODS

Bone marrow trephine biopsy specimens from 65 patients with MDS were immunophenotyped using a panel of antibodies. A minimum of 1000 cells from representative areas of marrow sections were counted at light microscopy. The association between immunohistological variables and prognosis was assessed.

RESULTS

Compared with normal control marrows (n = 23) no major abnormalities of T cells (CD3), T cell subsets (CD4, CD8, CD25, TCR gamma/delta) or natural killer cells (CD56, CD57) were seen in the 65 patients. In high risk MDS (RAEB, RAEB-t) 19% of the cases showed increased numbers of B lymphocytes compared with none in the low risk group (RA, RARS) (p < 0.0090). Only percentages of B cells above 3% significantly correlated with poor survival (p = 0.0121 for CD19, p = 0.046 for CD22).

CONCLUSIONS

The deviations in T lymphocyte counts seen in peripheral blood and in bone marrow aspirates could not be verified in bone marrow biopsy specimens.

Proliferation centres in B-cell malignant lymphoma, lymphocytic (B-CLL): an immunophenotypic study

Proliferation centres, also known as pseudofollicles, are present in approximately 90% of lymphocytic lymphomas (B-CLL). They consist of loosely arranged larger cells that often contain prominent nucleoli. In contrast to true B-cell follicles, which may be found entrapped within the small lymphocytic infiltrate in sections of B-CLL, proliferation centres are said not to contain follicular dendritic cells, although their presence has been occasionally recorded. We have carried out an immunohistochemical study of proliferation centres from 30 lymph node specimens of known cases of B-CLL, classified according to the Kiel classification, in six of which fresh frozen in addition to paraffin embedded tissue was available. We have compared proliferation centres with the surrounding small lymphocytic infiltrate and reactive B-cell follicles with respect to the presence of follicular dendritic cells and their associated network of IgM and complement, the cell proliferation fraction, the concentration of T-cells and the expression of bcl-2 protein. Most proliferation centres contained a delicate follicular dendritic cell network which was associated with IgM and complement, and showed a higher proliferation fraction than the surrounding small lymphocytic infiltrate. The proliferation centres contained more T-cells than the surrounding infiltrate and showed decreased expression of bcl-2 protein. Entrapped reactive B-cell follicles contained a much denser network of follicular dendritic cells, associated with much stronger expression of IgM and complement, and exhibited a very high proliferation fraction; they contained many T-cells and expressed very little bcl-2 protein.(ABSTRACT TRUNCATED AT 250 WORDS)

Interleukin-6 in multiple myeloma: correlation with disease activity and Ki-67 proliferation index

Interleukin-6 (IL-6) is supposed to be a growth factor in multiple myeloma (MM). Applying a bioassay and a modified ELISA, we measured serum IL-6 values in 64 patients with overt MM, seven patients with smouldering myeloma (SMM), 57 patients with monoclonal gammopathy of undetermined significance (MGUS) and 40 healthy volunteers as controls. IL-6 failed to discriminate between MGUS and MM, stage I, whereas comparison of MM, stage I and stage II/III (p = 0.0143), or comparison of stable disease/remission and progressive disease (p < 0.0001) revealed significant differences. Furthermore, we found significantly higher IL-6 values in overt MM compared to SMM (p = 0.0018). Using a Ki67/CD38 immunohistological double staining method we found a significant correlation between proliferation of bone marrow myeloma cells and serum IL-6 values in 15 patients (p = 0.005). These data demonstrate that IL-6 is a parameter of disease activity in MM and, beside its role in tumor biology, may become a valuable supplement to the established risk factors when selecting patients with unfavourable clinical course for more aggressive treatment modalities.

Long-term follow-up of patients with hairy cell leukaemia treated with pentostatin: lymphocyte subpopulations and residual bone marrow infiltration

Peripheral blood lymphocyte (PBL) subsets and bone marrow biopsies were analysed in six patients with hairy cell leukaemia (HCL) treated with 2'-deoxycoformycin (pentostatin, DCF) according to a phase II trial of the EORTC Leukemia Cooperative Group. All patients responded to DCF with four complete and two partial remissions according to conventional criteria. Within the PBL subsets, major changes concerned the CD4+ T cells, which during DCF therapy were distinctly suppressed to nadir values of 0.038-0.18 (median 0.126) x 10(9)/l. In five patients these cells returned to normal 3.0-49.5 (median 14.5) months after the last DCF injection. CD8+ cells were decreased to a lesser extent, and NK cell numbers improved during treatment. Bone marrow immunohistology applying the MoAb B-ly7 demonstrated residual hairy cells (HCs) in all of the six patients following DCF treatment with nadir HC numbers of 0.2-3.0% of bone marrow cells. Immunoglobulin gene rearrangement analysis of DNA obtained from these biopsies showed only germline bands, whereas rearranged bands had been present on the pretreatment specimens. Within the observation period of 15.5-54.0 (median 47.0) months after discontinuation of DCF therapy, immunohistology demonstrated a continuous increase in HC numbers in five of the six patients with clonal rearrangement detectable in bone marrow specimens from three of these patients at last follow-up date. Although established on the basis of a small number of patients, these data suggest that DCF treatment as currently employed in HCL is unable to eradicate the malignant B cell clone.

Immunohistologic studies of bone marrow biopsies on frozen sections: an analysis of 42 cases

An immunohistologic study of bone marrow biopsy frozen sections from 42 cases involved by a variety of reactive and neoplastic disorders is presented. Thirteen cases also were studied using other methods, including cytochemistry, surface marker analysis of cell suspensions, and/or DNA hybridization. Thirty-four of 42 cases (81%) were adequately phenotyped on frozen tissue using a panel of antibodies for hematolymphoid-associated antigens. The immunostains from the remaining eight cases were unsatisfactory, primarily as a result of heavy background staining. Eighteen cases were lymphoproliferative disorders of B-cell phenotype and 12 of these showed surface monotypic immunoglobulin expression by the frozen section technique. Six cases showed B- or pre-B-cell antigens but no surface immunoglobulins. Of the remaining 16 patients, two cases showed myeloid markers and three showed T-cell phenotype. Nine cases showed a mixture of polyclonal B- and T-cell populations. Keratin was demonstrated in a single case of metastatic carcinoma included in the study. These results indicate that the majority of hematopoietic processes can be successfully phenotyped on bone core frozen sections and demonstrate the usefulness of immunohistologic study of the frozen bone marrow biopsy specimens, especially when the specimens for other modalities are not available or are inadequate. The keys to achieving the best results from the frozen bone marrow immunohistochemistry were the gentle handling of the specimens and the preparation of high-quality, cryostat-cut frozen sections.

Immunoarchitecture of normal human bone marrow: a study of frozen and fixed tissue sections

To provide baseline information on the immunoarchitecture of normal bone marrow, we studied cryostat-cut, frozen, and paraffin-embedded, fixed tissue sections prepared from 21 core biopsies of normal bone marrow obtained during bone marrow harvests for transplantation. A large panel of antibodies was applied that included, for frozen tissue, Leu-6 (CD1), T11 (CD2), Leu-3a (CD4), Leu-1 (CD5), Leu-2a (CD8), J5 (CD10), My7 (CD13), Leu-11 (CD16), B4 (CD19), B1 (CD20), B2 (CD21), Tac (CD25), My9 (CD33), T200 (CD45), NKH-1 (CD56), kappa and lambda chains, beta F1, Ki-67, HLA-DR, TQ1, and keratin, and for fixed tissue, leukocyte common antigen (CD45), L26 (CD20), LN1 (CDw75), LN2 (CD74), LN3, LN4, LN5, MB1 (CD45R), MB2, MT1 (CD43), MT2 (CD45R), UCHL1 (CD45R0), BM1, Ki-1 (CD30), Leu-M1 (CD15), lysozyme, KP1 (CD68), actin, S100, neuron-specific enolase, vimentin, and keratin. On fresh-frozen sections CD19 and CD2 were the most reliable and sensitive markers for B and T cells, staining 5% and 9% of marrow cells, respectively. Immunoglobulins generally showed heavy background staining, which frequently precluded an accurate assessment. The CD4 to CD8 ratio in the bone marrow was reversed from that of peripheral blood. On fixed tissues, leukocyte common antigen was found in 14% of the marrow cells, corresponding roughly to the lymphocyte population. L26, a pan-B-cell marker, stained 3% of the marrow cells. Among the other B-cell markers, LN1 and MB2 stained a large number of cells (40% to 70%), indicating reactivity with cells of the myeloid or erythroid series in addition to lymphocytes. Among the T-cell markers, UCHL1 and MT1 stained 66% and 50% of the cells, respectively, which could be explained by their cross-reactivity with myeloid cells. Nonspecific myelomonocytic markers (Leu-M1, KP1, and lysozyme) also showed reactivity in a high percentage of cells. No particular architectural distribution patterns of B or T lymphocytes were noted in either frozen or fixed bone marrow specimens. The results of this study provide normal baseline data for the immunohistologic application of hematopoietic and lymphoid markers on frozen or fixed bone marrow biopsy specimens.

Bone marrow diagnosis in lymphoproliferative disorders: comparison of results obtained from conventional histomorphology and immunohistology

In this study we have investigated 313 bone marrow biopsies from 280 patients with lymphoproliferative disorders. Trephines were sectioned transversely to obtain one cylinder for cryostat sectioning and immunostaining and a second for histomorphological evaluation using a plastic-embedding technique. The results obtained by histomorphological and immunohistological evaluation were compared for their contribution to staging and classification. Using both techniques, bone marrow involvement was seen in 3/43 (7.0%) biopsies from patients with Hodgkin's disease and in 193/270 (71.5%) cases with non-Hodgkin's lymphoma, including multiple myeloma and acute lymphocytic leukaemia. Immunohistology proved superior in detecting minimal mainly interstitial bone marrow infiltration in 15 leukaemia/lymphoma cases. Biopsies showing infiltration with both methods (n = 157) were re-examined for classification of lymphomatous infiltrates. Whereas immunohistology did not provide additional information in cases with Hodgkin's disease and myeloma, this method was crucial for establishing the definitive diagnosis in a number of cases with acute lymphocytic leukaemia and non-Hodgkin's lymphoma. In all of six leukaemia cases, in which no or inadequate material was available for immunophenotyping of cell suspensions, immunohistology clearly defined the subtype. In the 140 cases of non-Hodgkin's lymphoma the majority of cases (76.4%) were identically classified. In some cases, with important prognostic and therapeutic implications, immunohistology alone provided the definitive diagnosis: T-cell lymphoma (n = 2), hairy cell leukaemia (n = 2) and centrocytic non-Hodgkin's lymphoma (n = 3). Bone marrow immunohistology is, therefore, an important supplement for classical lymphoma/leukaemia diagnosis. The differences observed between histomorphology and immunohistology emphasize the importance of lymph node biopsy in lymphoma classification.

Monoclonal antibody Ki-67: its use in histopathology

Monoclonal antibody Ki-67 is a reliable and easy means of accurately assessing the growth fraction of human neoplasms. Although the number of long-term follow-up studies is limited, it does appear to provide valuable prognostic information particularly in lymphoproliferative disease. Since the estimation of growth fraction is only one factor influencing tumour behaviour it would be naive to believe that measurement of this parameter alone, no matter how accurately, would provide the clinician with definitive prognostic information for all tumours. The antibody is also of use in research, providing a means of measuring proliferative activity in a variety of conditions besides malignancy, and may prove of value in monitoring tumour response to established and trial therapies.

Osteosclerotic myeloma with polyneuropathy and hypocalcemia

A case is presented of a 46-year-old man with multifocal osteosclerotic bone lesions, peripheral polyneuropathy and hypocalcemia. Histologic examination of a bone marrow biopsy disclosed a multiple myeloma. Immunoelectrophoresis revealed a small M-component identified as IgG-lambda. Osteosclerotic myeloma lacking any osteolytic lesions seems to be very rare and shows several different features as compared with classical myeloma. A review of the current literature suggests that multiple myeloma is not a uniform disease but rather a group of clinical syndromes characterized by the special properties of their proliferating plasma cell clones.

Immunohistological assessment of bone marrow biopsies from patients with hairy cell leukemia: changes following treatment with alpha-2-interferon and deoxycoformycin

Forty-six bone marrow biopsies from twelve hairy cell leukemia (HCL) patients, treated with either interferon(IFN)-alpha-2 (n = 8) or 2'deoxycoformycin(DCF) (n = 4), were examined using cryostat sections and an immunoperoxidase technique. Using this sensitive method we were able to demonstrate residual hairy cell (HC) infiltration in five cases, in which evaluation with conventional staining techniques on plastic embedded biopsies revealed complete remission. The amount of HCs in these five samples ranged from 1 to 7% (mean: 3%) of bone marrow cells. Consecutive biopsies in individual HCL patients revealed no changes of the immunological phenotype (CD19, CD22, CD25, CD10, CD11c, FMC7, HLA-DR, surface immunoglobulins) during IFN and DCF treatment. Within the infiltrated bone marrow a considerable number of "reactive" T lymphocytes was identified with prevalence of the T-helper (CD4+) subtype in untreated cases, whereas T-suppressor/cytotoxic (CD8+) cells were within the normal range. IFN treatment resulted in a reduction of CD4+ T lymphocytes (p less than 0.02). Minor alterations of CD8+ T lymphocytes and NK cells (HNK-1 + lymphoid cells) were found in bone marrow during IFN treatment. In DCF-treated patients bone marrow T lymphocytes were markedly reduced below the values of normal bone marrow. This DCF-induced T-cell depression might be related to the clinical observation of persistent cellular immune dysfunctions in HCL patients despite a DCF-induced remission.

Importance of an 85 kDa membrane glycoprotein for a variety of cell-cell interactions

The membrane molecule termed "7F7-antigen" has been found to be involved in several examples of cell-cell interactions. This 85 kDa glycoprotein with a protein core of about 55 kDa contains N-linked and O-linked carbohydrates. It has an isoelectric point of 8.0-8.5 and is expressed on 20% of peripheral blood mononuclear cells, 35% of peripheral blood B-cells, follicular dendritic cells and vascular endothelium. It is also expressed on activated T-cells and its expression on B-cells, fibroblasts and monocytes increases after treatment with PWM, interferon-gamma and after three days culture, respectively. The MAb 7F7 used to define this antigen inhibits the initiation of T-cell proliferation induced by anti-CD3, PHA, ConA and (weakly) allogenic stimulator cells, but does not affect the growth of IL-2 dependent T-cells and does not interfere with the killing of PHA-blasts by allogenic IL-2 dependent T-cells. 7F7 also inhibits the binding of C3-coated sheep erythrocytes to B-cells, the PMA-induced aggregation of U937 and the binding of activated T-cells to fibroblasts. The 7F7-antigen is expressed on some non-Hodgkin lymphomas of B-cell differentiation, particularly those with follicular structure, but not on Burkitt's lymphoma, ALL or carcinomas of various tissues. It is, however, found on fibrous tissue surrounding infiltrating carcinoma cells. The expression of a melanoma antigen, P3.58, which was shown to be identical to 7F7-antigen correlates with stage and spread of invasive melanoma. It was concluded that the 7F7-antigen, which is probably related to a previously described adherence molecule (ICAM-1), is of biological importance for the initiation of T-cell responses. With the possible exception of melanoma its expression on neoplastic cells in vivo is unlikely to be of importance for the spread of malignant disease.

Progressive preleukemia presenting amegakaryocytic thrombocytopenic purpura: association of the 5q- syndrome with a decreased megakaryocytic colony formation and a defective production of Meg-CSF

The authors present a patient with the typical clinical picture of an acquired amegakaryocytic thrombocytopenic purpura. After 16 months of observation, the patient developed acute myelomonocytic leukemia. During the preleukemic phase and after progression to overt leukemia, serial in-vitro analyses of megakaryocytic, granulocytic, erythrocytic and T-lymphocytic colony growth were carried out in a microagar culture system. At presentation, a marked diminution of CFU-M was observed, whereas CFU-E, BFU-E, CFU-C and CFU-TL were in the normal range. The CFU-M number remained at its low level during the whole observation period. The CFU-C number declined steadily during the preleukemic period, while BFU-E, CFU-E and CFU-TL remained constant until January 1985 when the patient developed AML. After progression to overt leukemia, a distinct reduction became evident in all colony-forming cells. Cytogenetic studies performed during the preleukemic phase indicated the presence of a 5q- chromosome. The authors submit evidence here that the patient was not only characterized by defective megakaryocytic colony formation but also by a deficiency of functional megakaryocyte colony-stimulating activity. No humoral or cellular inhibitors of CFU-M colony formation were found. It is concluded that in preleukemia with a 5q- chromosome the megakaryocytic cell lineage may be involved in the process that precedes overt leukemia at an earlier time than cells of granulocytic and erythrocytic lineages. In addition, it is shown here that megakaryocytopoiesis during the preleukemic period can be characterized by two different defects: first, an intrinsic megakaryocytic stem cell defect and, second, a deficiency of functional megakaryocytic colony-stimulating activity.